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Pulmonary tuberculosis among Southeast Asian refugee immigrants to British Columbia Arnott, Norman Montygue 1981

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II PULMONARY TUBERCULOSIS AMONG SOUTHEAST ASIAN REFUGEE IMMIGRANTS TO BRITISH COLUMBIA by Norman Montyque A r n o t t M.B., Ch.B. The U n i v e r s i t y o f Otago (NZ), 1968 A t h e s i s s u b m i t t e d i n p a r t i a l f u l f i l l m e n t o f t h e r e q u i r e m e n t s f o r t he degree o f Ma s t e r o f S c i e n c e i n The F a c u l t y o f Graduate S t u d i e s , Department o f H e a l t h Care and E p i d e m i o l o g y We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o the a c c e p t e d s t a n d a r d The U n i v e r s i t y o f B r i t i s h Columbia 1981 (c) * Norman. Montyque Arnott In presenting t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r reference and study. I f u r t h e r agree that permission f o r extensive copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by his r e p r e s e n t a t i v e s . It i s understood that copying or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l gain s h a l l not be allowed without my wri t t e n permission. Dr Norman M.Arnott Department of Health Care and Epidemiology. The U n i v e r s i t y of B r i t i s h Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 D E - 6 B P 7 5 - 5 1 1 E i i A b s t r a c t U n d e t e c t e d a c u t e Pulmonary T u b e r c u l o s i s i n the 50,000 r e f u g e e i m m i g r a n t s from S o u t h e a s t A s i a t o Canada would c o n s t i t u t e a s e r i o u s p u b l i c h e a l t h h a z a r d . The 10,000 S o u t h e a s t A s i a n r e f u g e e immigrants t o B r i t i s h Columbia i n 1979/80 were r e s c r e e n e d f o r a c u t e Pulmonary T u b e r c u l o s i s d e s p i t e p r o v i n c i a l and f e d e r a l h e a l t h a u t h o r i t i e s d i s a g r e e -i n g on the need f o r such r e s c r e e n i n g . T h i s t h e s i s d e m o n s t r a t e s t h a t the r e s c r e e n i n g o f the r e f -ugee i m m i g r a n t s was w a r r a n t e d by: A) Comparing t h e r a t e p e r 100,000 p o p u l a t i o n w i t h a c u t e Pulmonary T u b e r c u l o s i s among 1) The S o u t h e a s t A s i a n r e f u g e e immigrants a r r i v i n g i n B r i t i s h Columbia i n 1979/80 w i t h the r a t e s o f ac u t e Pulmonary T u b e r c u l o s i s per 100,000 p o p u l a t i o n f o r t h e t h r e e - y e a r p e r i o d 1976/78 among 2) the g e n e r a l p o p u l a t i o n of B r i t i s h C o lumbia, 3) t h e r e g i s t e r e d n a t i v e I n d i a n p o p u l a t i o n o f B r i t i s h C o l u m b i a , 4) the non-refugee Asian- immigrant p o p u l a t i o n a r r i v i n g i n B r i t i s h C o l u m b i a , and B) E s t i m a t i n g t h e i n c r e a s e d r i s k o f acute Pulmonary Tuber-c u l o s i s t o the g e n e r a l p u b l i c from the pr e s e n c e o f the 10,000 r e f u g e e immigrants i n B r i t i s h C o lumbia. i i i A g e - s p e c i f i c r a t e s of a c u t e Pulmonary T u b e r c u l o s i s and the p r e v a l e n c e r a t e s of a c u t e Pulmonary T u b e r c u l o s i s c o n -f i r m e d b a c t e r i o l o g i c a l l y were c a l c u l a t e d w i t h s t a t i s t i c s e x t r a c t e d from t h e r e c o r d s of the D i v i s i o n o f T u b e r c u l o s i s C o n t r o l o f B r i t i s h C o l u m b i a , the F e d e r a l Department o f H e a l t h and W e l f a r e , and t h e Department o f I m m i g r a t i o n . Comparison o f t h e a g e - s p e c i f i c r a t e s demonstrated t h a t a c u t e Pulmonary T u b e r c u l o s i s o c c u r r e d 6 times more f r e q -u e n t l y i n the r e f u g e e i m m i g r a n t s t h a n i n the g e n e r a l pop-u l a t i o n o f B r i t i s h C o l u m b i a , and 1.25 times more f r e q u e n t l y i n the r e f u g e e A s i a n immigrants t h a n i n the non-refugee A s i a n i m m i g r a n t s . Comparison o f t h e p r e v a l e n c e r a t e s demonstrated t h a t a c u t e Pulmonary T u b e r c u l o s i s c o n f i r m e d b a c t e r i o l o g i c a l l y o c c u r r e d 3 t i m e s more f r e q u e n t l y i n the r e g i s t e r e d n a t i v e I n d i a n p o p u l a t i o n of B r i t i s h Columbia t h a n i n the r e f u g e e immig-r a n t s t o B r i t i s h C o l u m b i a . The e x t r a p u b l i c h e a l t h r i s k o f a c t u e Pulmonary T u b e r c u l o s i s from t h e pr e s e n c e o f 10,000 r e f u g e e immigrants i n B r i t i s h C o lumbia f o r one y e a r was e s t i m a t e d t o be 730 i n 10^ f o r each member o f t h e g e n e r a l p o p u l a t i o n o f B r i t i s h Columbia. The r a t e o f a c u t e Pulmonary T u b e r c u l o s i s o c c u r r i n g i n t h e 10,000 r e f u g e e i m m i g r a n t s a r r i v i n g i n B r i t i s h Columbia iv i n 1979-1980 c o n f i r m e d t h a t the r e s c r e e n i n g o f the r e f u g e e i m m i g r a n t s was w a r r a n t e d . Recommendations were made t o c e n t r a l i z e the r e s c r e e n i n g program w i t h i n B r i t i s h Columbia so as t o m i n i m i z e the p u b l i c h e a l t h hazards o f a c u t e P u l -monary T u b e r c u l o s i s o c c u r r i n g i n t h e Southeast A s i a n r e f -ugee i m m i g r a n t s . V T a b l e o f C o n t e n t s Index i - v i L i s t o f T a b l e s v i i - v i i i L i s t o f F i g u r e s i x L i s t o f A p pendices x vi Index Page 1. Introduction 1 1.1 General 1 1.2 Object of the Study 2 1.3 Comparison Groups . 3 1.4 Non-Refugee Asian Immigrants to B.C. 1976, . 1977, 1978 4 1.5 Registered Native Indians i n B r i t i s h Columbia 1976, 1977, 1978 . . . 4 1.6 Sources and Limitations of Data 4 1.7 Def i n i t i o n s 7 1.7.1 General Population 7 1.7.2 Registered Native Indians 7 1.7.3 Non-Refugee Asian Immigrants .. 7 1.7.4 Refugee Immigrants 8 1.7.5 Landed Immigrant 8 1.7.6 Incidence 8 1.7.7 Prevalence 9 1.7.8 Pulmonary Tuberculosis ,. . . 9 1.7.9 B a c i l l a r y Status 10 1.7.10 Radiographical C l a s s i f i c a t i o n of Pulmonary Tuberculosis 10 1.7.11 Pre-Immigration Medical Examination 11 1.7.12 Rescreening Program 11 1.7.13 Disease-Specific Mortality Rate 11 1.7.14 Disease-Specific Morbidity Rate 12 1.7.15 Disease-Specific H o s p i t a l i z a t i o n Rate 12 1.7.16 Chemoprophylaxis 12 v i i v P a g e 1.7.17 Compliance 12 1.7.18 Summary 12 2. S t a t i s t i c a l Trends 13 2.1 Trends i n Immigration 13 2.2 Trends i n Morbidity 14 2.3 Incidence of Tuberculosis Among the Foreign Born 20 2.3.1 S t a t i s t i c a l Trends 22 2.4 Incidence of Tuberculosis Among Various Im-migrant Population Groups 23 2.5 Suspected High Incidence of Pulmonary Tub-erc u l o s i s Among Refugee Immigrants 25 2.6 Summary 26 3. Epidemiology of Tuberculosis 27 3.1 Mortality 27 3.2 Causes of Death Due to Tuberculosis 27 3.3 Cohort Analysis of Tuberculosis Mortality .. 27 3.4 Tuberculosis Morbidity 29 3.5 Comparisons With Other Countries 30 3.6 Various Population Groups i n Canada 30 3.7 Reactivation of Cases of Inactive Pulmonary Tuberculosis =. 33 3.8 Age and Sex-Specific Rates of Tuberculosis . 36 3.9 Importance of B a c t e r i o l o g i c a l Confirmation . 36 3.10 Fate of People with Pulmonary Tuberculosis . 36 3.11 Summary 39 4. General Description of Tuberculosis 40 4.1 General 40 4.2 Screening for Infection and Disease 40 v i i i Page 4.3 Diagnosis of Active Disease 41 4.4 Symptoms of Tuberculosis 41 4.5 Tuberculin Test 42 4.6 Booster Phenomenon 45 4.7 Small P o s i t i v e Reactions to the Tuberculin Skin Test 46 4.8 Tuberculin Test Amongst the Refugee Immig-rants 47 4.9 Summary 50 5. Control Measures *. 51 5.1 H i s t o r i c a l Approach 51 5.2 H o s p i t a l i z a t i o n 51 5.3 Hospital Employees 52 5.4 Select Groups "... 52 5.5 Public Health Programs 52 5.6 D i v i s i o n of Tuberculosis Control 53 5.7 The Medical Profession and Tuberculosis Control 53 5.8 Immigration 53 5.9 V i s i t o r s and Students 54 5.10 B.C.G 54 5.11 Chemoprophylaxis • 55 5.11.1 Drug Resistance 56 5.12 Use of Isoniazid 57 5.13 Negative Tuberculin Skin Reactors 57 5.14 Risk of Adverse Reactions 57 5.15 Dose and Duration of Chemoprophylaxis 60 5.16 Precautions • 60 5.17 Alternative Drugs 60 ix Page 5.18 Non-Compliance 61 5.19 Summary 62 6. Methods 64 6.1 Introduction 64 6.2 Rationale for Comparing Morbidity Rates .... 64 6.2.1 Mortality Rate 64 6.2.2 Morbidity Rates 64 6.2.3 H o s p i t a l i z a t i o n Rates 65 6.3 Population Groups to be Compared 65 6.3.1 Age-Specific Incidence of Pulmonary Tuber-c u l o s i s for the General Population i n B r i t i s h Columbia 65 6.3.2 Age-Specific Incidence of Pulmonary Tuber-c u l o s i s for Non-Refugee Asian Immigrants to B r i t i s h Columbia for 1976, 1977, and 1978 66 6.3.3 Age-Specific Rate of Pulmonary Tubercul-osis Among Registered Native Indians i n B r i t i s h Columbia for 1976 , 1977, and 1978 68 6.4 Incidence Versus Prevalence 70 6.5 Prevalence of B a c t e r i o l o g i c a l l y Confirmed Pulmonary Tuberculosis 72 6.6 Culture-Positive Cases of Pulmonary Tuber-culo s i s 72 7. Results .'. . 75 7.1 General 75 7.2 Rates of Pulmonary Tuberculosis Among the General Population and Non-Refugee Asian Immigrants 75 7.3 Estimate of the Maximum Possible Prevalence of Pulmonary Tuberculosis Among the Gen-e r a l Population 75 X Page 7.4 E s t i m a t e o f the Maximum P o s s i b l e P r e v a l e n c e of Pulmonary T u b e r c u l o s i s Among Non-Ref-ugee A s i a n Immigrants 77 7.5 Rate o f Pulmonary T u b e r c u l o s i s Among R e f -ugee Immigrants A d j u s t e d f o r Spontaneous R e m i s s i o n 78 7.6 A d j u s t e d R a tes o f Pulmonary T u b e r c u l o s i s Among R e g i s t e r e d N a t i v e I n d i a n s i n B r i t i s h C olumbia 78 7.7 Cases o f Pulmonary T u b e r c u l o s i s C o n f i rmed B a c t e r i o l o g i c a l l y 81 7.7.1 Rate o f Pulmonary T u b e r c u l o s i s C o n f i rmed B a c t e r i o l o g i c a l l y Among G e n e r a l P o p u l -a t i o n 81 7.8 Cases o f Pulmonary T u b e r c u l o s i s C o n f i rmed B a c t e r i o l o g i c a l l y Among Non-Refugee A s i a n Immigrants f o r 1976, 1977, and 1978 81 7.9 Cases o f Pulmonary T u b e r c u l o s i s Confirmed B a c t e r i o l o g i c a l l y Among R e g i s t e r e d N a t i v e I n d i a n s 82 7.10 Cases o f Pulmonary T u b e r c u l o s i s C o n f i rmed B a c t e r i o l o g i c a l l y Among Refugee Immigrants 83 7.11 Summary 83 8. D i s c u s s i o n 85 8.1 Comparison o f R a t e s o f Pulmonary T u b e r c u l -o s i s Among 1) t h e Refugee Immigrants and 2) t h e G e n e r a l P o p u l a t i o n 86 8.2 Comparison o f P r e v a l e n c e R a tes o f Cases C o n f i r m e d B a c t e r i o l o g i c a l l y 86 8.3 Comparison o f the Rates o f Pulmonary Tuber-c u l o s i s Among Non-Refugee Immigrants 87 8.4 Comparison o f the Rates o f Pulmonary Tuber-c u l o s i s Between t h e Refugee Immigrants and R e g i s t e r e d N a t i v e I n d i a n s , i n B r i t i s h C olumbia 88 8.5 Comparison o f the Rate o f Cases o f Pulmon-a r y T u b e r c u l o s i s C o n f i rmed by C u l t u r e o f M. t u b e r c u l o s i s 89 xi Page 8.6 Early Radiological Diagnosis of Pulmonary Tuberculosis 90 8.7 Federal Immigration Screening Policy 90 8.8 Early Disease Pattern Suggesting Recent Infection 94 8.9 Estimation of the Extra Public Health Hazard due to Admission of Refugee Immigrants with Pulmonary Tuberculosis 95 8.10 Summary 97 9. Conclusions and Recommendations 99 9.1 Pre-Immigration Screening 99 9.2 Recommendations 99 9.2.1 Alternative 1 99 9.2.2 Alternative 2 101 9.2.3 Alternative 3 101 9.3 Advantages of Centralized Rescreening 102 9.4 Confirmation of Hypothesis . 103 9.5 Summary 104 Appendices 1 - 5 'O^^ - 121 References 122 - 129 Acknowledgements 130 x i i L i s t of Tables Page Table 1 Yearly Rate per 100,000 Population of Active Tuberculosis for 1970 - 76 for 4 Sub-Groups of Population and Average Annual Rates of Decline 18 Table 2 Contribution of Foreign-born to Total Active Tuberculosis ( A l l Types) by Prov-ince Area, i n Canada 1971 - 75 19 Table 3 Morbidity of Active Tuberculosis i n Peo-ple Born i n Various Countries (1970-72). 21 Table 4 Tuberculin Test Response i n 762 Refugee Immigrants. Size of Skin Reaction to 5 T.U. PPD-S (i n mm) 48 Table 5 Registered Indians Screened for Years 1976 - 1978 69 Table 6 Comparison of Rates of Pulmonary Tuber-c u l o s i s Amongst Refugee Immigrants and General Population i n B. C 76 Table 7 Age-Specific Rate of Pulmonary Tubercul-osis Amongst Refugee Immigrants Contrasted with Age-Specific Incidence Amongst Nat-ive Indians 1976 - 1978 79 Table 8 Age, Sex, Tuberculin Response, Radiolog-i c a l Diagnosis of Refugee Immigrants Diagnosed as Pulmonary Tuberculosis, May, 1980, from 3,125 Rescreened i n B.C. .... 84 Table 9 Percentage of Radiological Diagnoses i n Various C l a s s i f i c a t i o n s f o r Refugee Immig-rants and General Population, 1976-78 .. 91 Table 10 Radiological Diagnosis of Pulmonary Tuber-cu l o s i s Amongst the Refugee Immigrants and General Asian Immigrants, 1976-78 92 Table 11 Contrast Radiological Diagnoses Amongst the Refugee Immigrants and Native Indians 93 x i i i L i s t o f T a b l e s ( c o n t ' d ) A p p e n d i c e s Page T a b l e A l C a l c u l a t i o n A g e - S p e c i f i c I n c i d e n c e Pulmonary T u b e r c u l o s i s i n G e n e r a l P o p u l a t i o n - B.C. - 1976,»77,'78 105 T a b l e A2 R a d i o l o g i c a l Diagnoses - New A c t i v e Pulmonary T u b e r c u l o s i s i n the Refugee Immigrants and G e n e r a l P o p u l a t i o n , B.C., 1976,'77,»78 107 T a b l e A4 Number o f Refugee Immigrants i n each Age Group R e s c r e e n e d 108 T a b l e A5 C a l c u l a t i o n A g e - S p e c i f i c Rate o f Tuber-c u l o s i s Amongst Refugee Immigrants, 1979/80 109 T a b l e A6 Number o f Refugee Immigrants Rescreened May, 1980 110 T a b l e A7 Computer L i s t , Age/Sex Breakdown o f Refugee Immigrants H a v i n g A r r i v e d i n B r i t i s h C olumbia up t o June 11, 1980 .. I l l T a b l e A8 C o u n t r y o f L a s t Permanent R e s i d e n c e o f Immigrants D e s t i n e d f o r B r i t i s h C o lumbia 114 T a b l e A9 Age o f Immigrants Bound f o r B r i t i s h C olumbia 115 T a b l e A10 A s i a n Immigrants t o B r i t i s h Columbia 1976-78 A c c o r d i n g t o Age Grouping 116 T a b l e A l l Age G r o u p i n g o f A s i a n Immigrants t o B r i t i s h C olumbia 117 T a b l e A12 Cases o f Pulmonary T u b e r c u l o s i s O ccur-r i n g Amongst A s i a n Immigrants i n F i r s t 12 Months i n B r i t i s h C o l u m b i a , A d j u s t e d f o r P l a c e o f I n i t i a l D i a g n o s i s ( i n B.C. o r ex-B.C.) f o r 1976, 1977, and 1978 ... 118 T a b l e A13 A g e - S p e c i f i c I n c i d e n c e o f Pulmonary Tu-b e r c u l o s i s Amongst A s i a n Immigrants w i t h I n i t i a l D i a g n o s i s B e i n g Made i n B r i t i s h C o lumbia W i t h i n Twelve Months o f Immig-r a n t ' s A r r i v a l i n P r o v i n c e f o r Y e a r s 1976, 1977, 1978 119 T a b l e A14 A g e - S p e c i f i c I n c i d e n c e o f Pulmonary Tu-b e r c u l o s i s Amongst R e g i s t e r e d I n d i a n s . 120 x i v •/ ( L i s t o f F i g u r e s Page F i g u r e 1 I n t e r n a t i o n a l I m m i g r a t i o n t o B r i t i s h C o lumbia 1963 - 1978 15 F i g u r e 2 Annual I m m i g r a t i o n t o Canada, 1963 -1978 16 F i g u r e 3 I n t e r n a t i o n a l I m m i g r a t i o n Trends i n t o Canada from Europe, A s i a , N o r t h and C e n t r a l A m e r i c a , 1974 - 1978 17 F i g u r e 4 T u b e r c u l o s i s M o r t a l i t y p e r 100,000 Pop-u l a t i o n , Canada and U n i t e d S t a t e s , 1940 - 1975 . .. .' 28 F i g u r e 5 I n c i d e n c e o f T u b e r c u l o s i s p e r 100,000 P o p u l a t i o n , U.S.A. and Canada, 1950 -1977 31 F i g u r e 6 New Cases o f A c t i v e T u b e r c u l o s i s p e r 100,000 P o p u l a t i o n i n U.S.A., Canada, and S e l e c t e d D e v e l o p i n g C o u n t r i e s -1973 32 F i g u r e 7 Average Annual I n c i d e n c e Rates o f A c t i v e T u b e r c u l o s i s ( a l l forms) p e r 100,000 P o p u l a t i o n Among Four P o p u l a t i o n Groups i n Canada f o r 1974 - 1978 34 F i g u r e 8 Average Annual I n c i d e n c e (1970 - 1974) of A c t i v e T u b e r c u l o s i s Among R e g i s t e r e d I n d i a n s i n V a r i o u s Regions o f Canada p e r 100,000 P o p u l a t i o n 35 F i g u r e 9 Average Annual Rate o f A c t i v e T u b e r c u l -o s i s ( a l l forms) p e r 100,000 P o p u l a t i o n i n Canada, 1970 - 1976 37 F i g u r e 10 F a t e o f Cases o f Pulmonary T u b e r c u l o s i s C o n f i r m e d B a c t e r i o l o g i c a l l y A f t e r Two Ye a r s under D i f f e r e n t Treatment Regimes 38 F i g u r e 11 Comparison o f S k i n S e n s i t i v i t y t o I n t e r -m e diate S t r e n g t h P.P.D. i n two V i l l a g e s i n B o l i v i a 44 F i g u r e 12 H i s t o g r a m o f T u b e r c u l i n R e a c t i o n s o f 763 Refugee Immigrants S k i n T e s t e d w i t h 5 T.U. P.P.D. i n Vancouver, B.C. by Jun e , 1980 ... 49 F i g u r e 13 I n c i d e n c e o f H e p a t i t i s w i t h I n c r e a s i n g Age 59 XV Appendix 1 Appendix 2 Appendix 3 L i s t of Appendices Calculation of Age-Specific Incidence of Pulmonary Tuberculosis i n General Population of B r i t i s h Columbia, 1976, 1977, and 1978 , Derivation of Age-Specific Rate of Pulmonary Tuberculosis Among the Ref-ugee Immigrants; June 1, 1979 - May 1, 1980 , Derivation of Age-Specific Population Groupings f o r Asian Immigrants Bound, for B r i t i s h Columbia, 1976 - 1978 Appendix 4 Age-Specific Incidence of Pulmonary Tuberculosis Among Registered Indians Appendix 5 Letter from Dr. A. Heimann to a l l Medical Health O f f i c e r s , Page 105 108 112 120 121 1 1. Introduction 1.1 General In 1979, the c r i t i c a l s i t u a t i o n of refugees i n Southeast Asia led the Federal Government of Canada to encourage the provinces to admit refugee immigrants. Special prov-i n c i a l immigration l e g i s l a t i o n was passed to f a c i l i t a t e the admission of 10,000 otherwise excluded Southeast Asian refugee immigrants to B r i t i s h Columbia under a public sponsorship program. In his report e n t i t l e d "Evaluation of the Tuberculosis (1) Problem and Control Measures i n Canada", Grzybowski (Professor of Medicine, University of B r i t i s h Columbia) stated "Tuberculosis i s a p a r t i c u l a r l y common disease among the recent (1979) immigrants from Asia. It i s debatable whether any sensible and e f f e c t i v e tubercul-osis control program could or should be i n s t i t u t e d i n (2) t h i s group. Larsen , the P r o v i n c i a l Epidemiologist for B r i t i s h Columbia i n 1979, stated "These (Indo-Chinese) refugees come from a part of the world where chronic communicable diseases are s t i l l very common and where health services have been badly disrupted by wars fo r a number of years. They have been l i v i n g i n camps under conditions where communicable diseases are e a s i l y spread and r e a d i l y acquired. 2 "We have evidence that the medical examinations c a r r i e d out by the Federal Government overseas have f a i l e d to detect a l l of the serious chronic communicable diseases present i n the Indo-Chinese refugees who have already arrived. We believe t h i s s i t u a t i o n could r e s u l t i n the spread of these diseases to sponsors and to the public generally. "Discussions with the Federal authorities have convinced us that they are not prepared to make any changes i n t h e i r present p o l i c i e s or procedures to correct this problem and we believe that any additional examinations or treatments decided upon w i l l have to be c a r r i e d out by p r o v i n c i a l s t a f f and at p r o v i n c i a l expense." The diseases s p e c i f i e d by Dr. Larsen were: 1) Tuberculosis 2) Sexually transmitted diseases 3) I n t e s t i n a l parasites and pathogenic bacteria 4) Hepatitis Each of these diseases or groups of diseases has i n d i v i d u a l and public health s i g n i f i c a n c e . An ad hoc advisory group to the Ministry of Health agreed that the greatest public health hazard was associated with tuberculosis and s p e c i f -(3) i c a l l y Pulmonary Tuberculosis. 1.2 Object of the Study D i f f e r i n g opinions of the need to rescreen the Southeast Asian refugee immigrants f o r Pulmonary Tuberculosis were 3 expressed by Dr. Grzybowski and Dr. Larsen. It i s hypothesized that the rescreening of the Southeast Asian refugee immigrants f o r acute Pulmonary Tuberculosis was warranted. This i s assessed by: A) comparing the rates per 100,000 population with acute Pul-monary Tuberculosis among: ( i ) 1) The Southeast Asian refugee immigrants a r r i v i n g i n B r i t i s h Columbia i n 1979-80 2) The general population of B r i t i s h Columbia f o r 1976, 1977, and 1978 3) .Registered Native I n d i a n s ( 1 1 1 * i n B r i t i s h Columbia for 1976, 1977, and 1978 A) Non-refugee Asian immigrants to B r i t i s h Columbia i n 1976, 1977, 1978, and B) Estimating the increased r i s k of Pulmonary Tuberculosis to the general public from the presence of the refugee immigrants i n B r i t i s h Columbia. 1.3 Comparison Groups General Population i n British'Columbia,1976-78 I This i s the base l i n e comparison between the general pop-u l a t i o n , a heterogeneous group, and the refugee immigrants. The incidence rate of Pulmonary Tuberculosis i n the general population declined s t e a d i l y from 21.3 per 100,000 i n 1970 to 13.7 per 100,000 i n 1976 (Table 1, Page 18). Footnotes: ( i ) Defined Page 8 ( i i i ) Defined Page 7 ( i i ) Defined Page 7 (iv) Defined Page 7 4 The introduction of the refugee immigrants with a suspected high prevalence of Pulmonary Tuberculosis into the general population could reverse the downward trend of the incidence rate i n the general population. ' 1.4 Non-refugee Asian Immigrants to B.C. 1976, 1977, 1978 Even before the government sponsored refugee immigrant move-ment i n June, 1979, non-refugee Asian immigrants were an increasing percentage of t o t a l immigration to Canada and to B r i t i s h Columbia. This comparison w i l l i d e n t i f y the extra r i s k of Pulmonary Tuberculosis associated with " r e f -ugee" status. 1.5 Registered Native Indians i n B r i t i s h Columbia 1976, 1977, 1978 Grzybowski^^ stated "Rates (of tuberculosis) among Canadian Indians are consistently some ten times higher than among other Canadians; what i s even more worrying i s that i n recent years these rates have shown no i n d i c a t i o n of a declines" The comparison with registered native Indians w i l l compare the rate of Pulmonary Tuberculosis among the refugee immigrants with an acknowledgedly high prevalence, high incidence group, the registered native Indians. 1.6 Sources and Limitations of Data The D i v i s i o n of Tuberculosis Control of B r i t i s h Columbia i s involved i n a l l phases of Diagnosis, Treatment, and Prevention i n B r i t i s h Columbia. The D i v i s i o n i s 5 a s s i s t e d by private physicians, Public Health personnel, and other health agencies i n the province which includes the Federal Health and Welfare s t a f f of the P a c i f i c region providing health care to native Indians. The main sources of data for the D i v i s i o n of Tuberculosis Control are: 1) Statutory n o t i f i c a t i o n of tuberculosis from l e g a l l y q u a l i f i e d medical p r a c t i t i o n e r s (including medical sup-erintendents or persons i n charge of general or other hospitals) to the l o c a l Medical O f f i c e r of Health who i n turn must n o t i f y the D i v i s i o n of Tuberculosis Control. 2) Tuberculosis bacteriology reports from the p r o v i n c i a l government laboratories and other laboratories of cer-t a i n larger general hospitals. 3) Admission and separation cards of a l l persons treated i n tuberculosis hospitals i n B r i t i s h Columbia. 4) Medical c e r t i f i c a t e s of death from the o f f i c e of the Registrar General on a l l persons i n whom turberculosis i s mentioned among the causes of death. 5) Out-patient reports on persons receiving drug treatment (free of charge) for active tuberculosis from chest c l i n i c s and private physicians. 6 ) N o t i f i c a t i o n from other j u r i s d i c t i o n s of B r i t i s h Columbia residents found to have tuberculosis. 7) Miscellaneous reports, e.g. from Workers' Compensation Board and Federal Department of Immigration. 6 While the statutory n o t i f i c a t i o n from private physicians i s far from complete, since there are many other sources of information, the information compiled and d i s t r i b u t e d by the D i v i s i o n of Tuberculosis Control represents an accur-ate picture of tuberculosis i n B r i t i s h Columbia. Other sources of information were the Canadian Employment and Immigration Commission, Vancouver, which supplied d e t a i l s of the numbers of refugee immigrants a r r i v i n g i n B r i t i s h Columbia, and the various health d i s t r i c t s which supplied information on the numbers of immigrants s e t t l i n g i n the i n d i v i d u a l d i s t r i c t s and being screened by health d i s t r i c t s t a f f . This l a t t e r information was obtained through the o f f i c e of Dr. Alan Keimann, Federal F i e l d Epidemiologist, P r o v i n c i a l Public Health Building, 1515 Blanshard S t r e e t 3 V i c t o r i a , i n answer to a questionnaire A p r i l , 1980 (Appendix 5). Immigration s t a t i s t i c s were obtained from S t a t i s t i c s Canada and c a l c u l a t i o n of the age breakdown of immigrants from Asia was done using the method explained i n Appendix 3. The Willow Chest C l i n i c ; Federal Health and Welfare, Indian A f f a i r s Department; and the Metropolitan Board of Health, Refugee Resettlement Program, Vancouver, B. C , provided further information and s t a t i s t i c s on the refugee immigrants. To enable comparisons to be drawn with the s t a t i s t i c s put out by the D i v i s i o n of Tuberculosis Control, f i v e age group-ings have been used - (years) 0 - 14, 15 - 24, 25 - 44, 7 45 - 64, 65 and over. Other factors influencing this d e c i s -ion were the natural h i s t o r y of the disease, the number of cases occurring i n the various age brackets, and data published on tuberculosis by S t a t i s t i c s Canada. 1.7 D e f i n i t i o n s 1.7.1 General population: Individuals permanently resident i n B r i t i s h Columbia, including native Indians and foreign-born i n d i v i d u a l s . 1.7.2 Registered Native Indians: Individuals born i n B r i t i s h Columbia whose ethnic o r i g i n i s native Indian. These i n d i v i d u a l s are registered as native Indian under Federal law and r e t a i n a l l the r i g h t s and r e s p o n s i b i l i t i e s due to t h e i r race. Fluctuations may occur i n these population figures since native Indians may choose to move off the reserve at which time they lose t h e i r registered Indian status. Should they then choose to return to the reserve, they are c l a s s i f i e d 'non-Indian status resident on the reserve.' 1.7.3 Non-Refugee Asian Immigrants: Individuals foreign-born now permanently resident i n B r i t i s h Columbia. For immigration purposes, these persons gave as t h e i r "country of l a s t permanent residence" one of the following: 8 A f g h a n i s t a n ' Japan Q a t a r B a h r a i n J o r d a n S a u d i A r a b i a B a n g a l a d e s h Kampuchea Si n g a p o r e B r u n e i Korea S r i Lanka C h i n a Laos Taiwan Cyprus Macao T h a i l a n d Hong Kong M a l a y s i a U n i t e d Arab E m i r a t e I n d i a N e p a l South Vietnam I n d o n e s i a Oman Yeman Arab R e p u b l i c I r a q P a k i s t a n Yeman D e m o c r a t i c P e o p l e s ' R e p u b l i c , I s r a e l P h i l i p p i n e s 1.7.4 Refugee Immigrants: Those s o u t h e a s t A s i a n i m m i g r a n t s a r r i v i n g i n B r i t i s h Columbia (between June, 1979, and Dec-ember, 1980) under the s p e c i a l p r o v i n c i a l s p o n s o r s h i p p l a n f o r r e f u g e e s . En r o u t e t o Canda, the r e f u g e e i m m i g r a n t s were accommodated a t one o r more r e f u g e e camps i n c o u n t r i e s such as L a o s , Cambodia, o r Hong Kong. 1.7.5 Landed Immigrant: An i n d i v i d u a l who has a r r i v e d i n Canada and, i n d i c a t i n g an i n t e n t i o n t o r e s i d e p e r m a n e n t l y i n Canada, has a p p l i e d f o r and been g r a n t e d 'Landed Immigrant S t a t u s . ' 1.7.6 I n c i d e n c e : The i n c i d e n c e o f a d i s e a s e i s t h e number o f c a s e s o f t h e d i s e a s e o c c u r r i n g d u r i n g a s p e c i f i e d p e r i o d o f t i m e . The i n c i d e n c e r a t e i s t h i s number p e r s p e c i f i e d 9 unit of p o p u l a t i o n . ^ 1.7.7 Prevalence: The frequency of a disease at a desig-nated point i n time. Expressed for a population at a spec-i f i e d time, the prevalence rate i s the proportion of the population which exhibits the disease at that p a r t i c u l a r t l - e . ' 6 ' 1.7.8 Pulmonary Tuberculosis: (1) Primary Pulmonary Tu-berculosis (formerly c a l l e d childhood-type tuberculosis). This type may follow immediately upon the f i r s t or primary i n f e c t i o n with tubercle b a c i l l i . At this time, tubercle b a c i l l i may spread throughout the body by the haematogenous route or through lymphatic channels. The multiple and scattered f o c i of i n f e c t i o n thus occurring may be the s i t e of active disease either immediately or many years l a t e r . Primary Pulmonary Tuberculosis i s a r e l a t i v e l y benign d i s -ease and frequently i s not diagnosed. Primary i n f e c t i o n with tubercle b a c i l l i i s mostly unrecognized. The only indication that such i n f e c t i o n has occurred i s the conversion of the tuberculin skin t e s t from negative to p o s i t i v e . Such an infected person i s at r i s k of developing tuberculosis (due to endogenous reactivation) f o r the rest of his l i f e . (2) Post-primary (adult-type, chronic) Pulmonary Tubercul-o s i s . This type r e s u l t s from a) The d i r e c t progression of primary tuberculosis, b) The subsequent r e a c t i v a t i o n of dormant f o c i due to the haematogenous or lymphatic d i s -semination of b a c i l l i at the time of the i n i t i a l i n f e c t i o n , 10 c) Exogenous r e - i n f e c t i o n , from a n o t h e r s o u r c e , subsequent t o t he i n i t i a l o r p r i m a r y i n f e c t i o n . 1 . 7 . 9 B a c i l l a r y S t a t u s : Cases of Pulmonary T u b e r c u l o s i s a r e p o s i t i v e b a c t e r i o l o g i c a l l y i f M. t u b e r c u l o s i s o r M. b o v i s ar e c u l t u r e d from sputum o r g a s t r i c washings. I f M. t u b e r -c u l o s i s i s d e m o n s t r a t e d from a sputum smear, t h e i n d i v i d u a l i s c o n s i d e r e d h i g h l y i n f e c t i o u s . A c c o r d i n g t o t h e D i v i s i o n (7) o f T u b e r c u l o s i s C o n t r o l ' s a n n u a l r e p o r t , 1 9 7 8 ; p r i m a r y a c t i v e c a s e s a r e 2 6 - 4 1 % p o s i t i v e on c u l t u r e , whereas m i n -i m a l l y a c t i v e c a s e s are 7 8 - 8 5 7 0 , m o d e r a t e l y a c t i v e c a s e s a r e 9 0 - 9 5 7 o , and f a r advanced cases a r e 9 5 - 1 0 0 7 , p o s i t i v e on c u l t u r e . 1 . 7 . 1 0 R a d i o g r a p h i c a l C l a s s i f i c a t i o n o f Pulmonary Tuber-c u l o s i s : Pulmonary T u b e r c u l o s i s may be c l a s s i f e d r a d i o g r a p h -i c a l l y as f o l l o w s : 1 ) M i n i m a l : These l e s i o n s a r e of s l i g h t t o moderate d e n s i t y but do n o t c o n t a i n d e m o n s t r a b l e c a v i t a t i o n . They may i n v o l v e a s m a l l p a r t o f one o r b o t h l u n g s b u t the t o t a l e x t e n t , r e -g a r d l e s s o f d i s t r i b u t i o n , s h o u l d n ot exceed t h e volume o f l u n g on one s i d e w h i c h i s p r e s e n t above the second chondro-s t e r n a l j u n c t i o n and t h e s p i n e o f t h e f o u r t h o r t h e body o f t h e f i f t h t h o r a c i c v e r t e b r a . T h i s c l a s s i f i c a t i o n a l s o a p p l i e s t o l e s i o n s w h i c h c a n n o t be seen on the c h e s t X - r a y b u t w h i c h a r e a s s o c i a t e d w i t h the c o n f i r m e d f i n d i n g o f t u b -e r c l e b a c i l l i i n sputum o r g a s t r i c a s p i r a t e s . 2) Moderately advanced: Lesions may be present i n one or both lungs, but the t o t a l extent should not exceed the f o l -lowing l i m i t s : disseminated lesions of s l i g h t to moderate density which may extend throughout the t o t a l volume of one lung, or the equivalent i n both lungs; dense and c o n f l u -ent lesions which are l i m i t e d i n extent to one t h i r d the volume of one lung; t o t a l diameter of c a v i t a t i o n , i f present, must be less than 4 cm. 3) Far Advanced: Lesions which are more extensive than moderately advanced. 1.7.11 Pre-Immigration Medical Examination: The medical examination of ALL immigrants performed by l o c a l physicians (most commonly i n the country of o r i g i n of the prospective immigrant) on behalf of the Department of Immigration Canada. Pre-immigratioh medical examination of the refugee immigrants was performed i n t r a n s i t camps i n which the refugees were housed while awaiting transport to Canada. 1.7.12 Rescreening Program: The medical examination of Southeast Asian refugee immigrants who had a r r i v e d i n B r i t i s h Columbia between June, 1979, and December, 1980. The rescreen (8) ing was recommended by Dr. A. Larsen and' was aimed' at ident i f y i n g diseases with p o t e n t i a l public health hazards. 1.7.13 Disease-Specific Mortality Rate: An incidence rate calculated by using as the numerator the number of deaths 12 occurring i n the population during the stated period (usually one year) due to the disease s p e c i f i e d , usually reported (9) on the basis of 100,000 persons. 1.7.14 Disease-Specific Morbidity Rate: An incidence rate used to include persons i n the population under consideration who become i l l i n the stated period of time, usually one year, due to the p a r t i c u l a r disease s p e c i f i e d . 1.7.15 Disease-Specific H o s p i t a l i z a t i o n Rate: An incidence rate calculated by using as the numerator persons i n the population under consideration who are admitted to ho s p i t a l i n the stated period of time, usually one year, due to the p a r t i c u l a r disease s p e c i f i e d . 1.7.16 Chemoprophylaxis: Koeprich defines chemoprophylaxis as a form of treatment f o r an i n f e c t i o n which has not yet occurred, i s just beginning, or i s i n an asymptomatic sub-c l i n i c a l state. 1.7.17 Compliance: i s defined as "action i n accordance with (12) a request or command." In medical terminology, the com-p l i a n t patient follows a therapeutic regimen explained by a physician; the non-compliant patient does not. 1.7.18 Summary Two d i f f e r i n g opinions on the necessity of rescreening the 13 refugee immigrants are o u t l i n e d . Whether the rescreening program was warranted w i l l be confirmed or denied by* a com-parison of the rate of acute Pulmonary Tuberculosis among the refugee immigrants with the rate of acute Pulmonary Tuberculosis among the general population, non-refugee Asian immigrants, and native Indians. The source and l i m i t a t i o n s of the data are explained and various d e f i n i t i o n s are given. 2. S t a t i s t i c a l Trends 2.1 Trends i n Immigration The fluctuations of immigration into B r i t i s h Columbia and Canada over the past years, 1963 to 1978, are demonstrated by Figures 1 & 2 (pages 15 & 16). From peaks of 225,000 i n 1966/67 and 1973/74, immigration into Canada has declined to 100,000 i n 1977/78. The fluctuations i n Canadian immig-r a t i o n are followed by fluctuations i n i n t e r n a t i o n a l immig-r a t i o n into B r i t i s h Columbia. From, the 19th century, one of the major sources of immigrants to Canada has been Europe. The change i n source away from Europe towards Asia i s graphically displayed by Figure 3, Page 17. The o v e r a l l decline i n t o t a l numbers i s shown by Figures 1 & 2, Pages 15 & 16. The proportional change i n immigration i s shown by Figure 3, Page 17. While Europe i s s t i l l the major source of immigrants to Canada, between 1974 and 1978 Asia became a signifcant source of immigrants. 14 F i f t y thousand refugee immigrants were admitted from Southeast Asia into Canada between 1979 and 1980; 10,000 were destined for B r i t i s h Columbia. 2.2 Trends i n Morbidity The yearly rates of active tuberculosis (ALL types) f o r the years 1970 to 1976 f o r 4 sub-groups of the population of Canada i s shown by Table 1 (page 18). Tuberculosis i n the general population i s d e c l i n i n g steadily:. 21.3 per 100,000 i n 1970 to ,13.7 per 100,000 i n 1976, an annual average decline of 5.970. For the foreign-born, i . e . immig-rants, the comparable rates are: 24.7 per 100,000 i n 1970 to 29.6 per 100,000 i n 1974, an annual average increase or D/O . While the number of cases of active tuberculosis i n Canada has been d e c l i n i n g s t e a d i l y , the number of cases i n the foreign-born groups has not shown a corresponding decline. As a r e s u l t , the proportion of a l l cases who were born outside Canada has s t e a d i l y r i s e n . This s i t u a t i o n varies across Canada (Table 2, page 19), being most s i g n i f i c a n t i n B r i t i s h Columbia and i n Ontario (excluding Toronto), the provinces with the largest proportions of foreign-born residents. Considering the column s p e c i f i c f o r B r i t i s h Columbia, be-tween 1971 and 1975 foreign-born residents comprised 22.TL. of the t o t a l population. Nine hundred and f i f t y - o n e cases Figure 1 In t e r n a t i o n a l Immigration to B r i t i s h Columbia 1963-78 Numbers a r r i v i n g i n thousands 35 30 25 20 15 10 5 1964 1966 1968 1970 1972 1974 1976 Source: Compiled from annual reports S t a t i s t i c s Canada 1Immigr '' . . . natural increase on an annual basis Immigration, emigration, i n t e r p r o v i n c i a l migration.and 1963-1976 ( I 3 ) Figure 2 Number of immigrants each year 000's 225 200 175 150 125 100 75 50 25 Annual Immigration to Canada 1963-1978 1964 1966 1968 1970 1972 1974 1976 Source: Compiled from annual reports S t a t i s t i c s Canada 'Immigration, emigration, i n t e r p r o v i n c i a l m i g r a t i o n natural increase on an annual b a s i s . ' 1963-1976U3) and OOO's. 90 80 70 |I 60 50 40 30 20 10 Figure 3 Int e r n a t i o n a l immigration trends i n t o Canada from Europe, A s i a , North and Central America 1974-1978 1974 1975 1976 1977 1978 Compiled from Canada Manpower and Immigration: Annual Immigration S t a t i s t i c s 1974-1978 Information Canada Ottawa(14) Key TABLE 1 Yearly Rates per 100,000 population of Active Tuberculosis f o r 1970-1976 f o r Four Sub-Groups of Population and Average Annual Rates of Decline 1970 1971 1972 1973 1974 1975 1976 Rate of Over 4 y r . Reg. No. 1970-74 353 369 440 400 425 484*** 459*** Indian *Pop. 251 258 265 270 278 **** **** Rate 140.8 143.2 166.2 147.9 152.9 - -2.1% Eskimo No. 130 107 70 63 52 51 30 •Pop. 17 18 18 19 19 20 20 Rate 765.7 609.7 386.3 337.0 269.9 260.1 150.0 16.2 Oth. No.** 3254 3159 2794 2617 2277 2001 1540 Can. *Pop. 17798 17998 18197 18420 1872 **** **** Rate 18.4 16.3 14.2 14.2 12.2 8.3% Non- No. 803 931 1022 1044 1016 1015 1014 Can. •Pop. 3250 3296 3341 3386 3431 **** **** Rate 24.7 28.3 30.6 30.8 29.6 -5.0% Total No. 4540 4566 4479 4124 3770 3551 3143 *Pop. 21297 21568 21821 22095 22446 22800 22993 Rate 21.3 21.2 20.5 18.7 16.8 15.6 13.7 5.9% Over 2 y r . 1974-76 22.2% 9.2% •Population in thousands. ••Includes non-registered Indians and country of b i r t h not known for years 1970-1974, •••Includes non-registered Indians also. ••••Size of population no available, therefore rates not computed. (15) Source: Grzybowski, S. "Evaluation of the Tuberculosis Problem and Control Measures in Canada" Table 20 Page 60 19 TABLE 2 Co n t r i b u t i o n o f Foreign-Born to T o t a l A c t i v e T u b e r c u l o s i s ( a l l types) by Province Area, i n Canada 1971-1975 To t a l Newfound-land & Quebec Ont a r i o P r a i r i e s B.C. Toronto Maritimes AIT A c t i v e Cases 20.496 2145 6288 5621 3700 2379 366 Cases i n non-Canadian Born #5146 41 533 2841 779 951 1 • % 25.1 1.9 8.5 50.5 21.0 40.0 0.3 Foreign-Born as % of 1971 15.3 P o p u l a t i o n 1.0 7.8 22.2 15.4 22.7 9.0 Source: D. Enarson, M. J . Ashley, and S. Grzybowski v T u b e r c u l o s i s i n Immigrants to Canada. A study of present-day Patterns i n R e l a t i o n to Immigration Trends and B i r t h p l a c e . Amercian Review of R e s p i r a t o r y Disease. 119, 14, 1979. 20 of tuberculosis (of a l l types), 40% of the t o t a l number of cases for B r i t i s h Columbia, were contributed by 22.1% of the population. 2.3 Incidence of Tuberculosis Among the Foreign-Born Immigrants to Canada are medically screened p r i o r to a r r i v a l and i n d i v i d u a l s with active tuberculosis are excluded from admission. Only occasionally are individuals with acute tuberculosis admitted under special m i n i s t e r i a l authority; they are then c l o s e l y monitored by the D i v i s i o n of Tuber-c u l o s i s Control. Table 3, page 21, sets out the morbidity of active tuberculosis among foreign-born residents i n Canada for the years 1970-1972. Individuals from areas with a high incidence of Pulmonary Tuberculosis tend to have a high incidence of tuberculosis i n Canada. Rates i n immigrant groups i n Canada approach but do not equal the incidence rates i n the countries of o r i g i n because of the pre-immigration screening and exclusion of active cases. Table 3, page 21, may be further subdivided into four groups: 7o of Foreign-Born i n Canada 7o Cases 1) Philippines to India 3.3 21.1 2) Finland to Greece 12.7 22.2 (continued page 22) 21 TABLE 3 Mor b i d i t y o f A c t i v e T u b e r c u l o s i s i n People Born i n Various C o u n t r i e s (1970-72). Incidence Rate (per 100,000) Proportion {%) of Foreign-born i n Canada Country o f B i r t h J n C o u n t r y I n % Q f % Q f o f B i r t h Canada Population Cases P h i l i p p i n e s 300.0 219.5 0J.4. 3.1 China - 190.7 1.7 11.9 India - 143.2 1.2 6.1 F i n l a n d 98.8 77.6 0.8 2.1 Portugal 119.0 61.0 2.2 4.8 Yugoslavia 116.3 47.7 2,4 4.1 U.S.S.R. - 44.1 4.9 7.7 Greece 106.9 42.3 2.4 3.6 A u s t r i a 66.5 32.1 1.2 1.4 Poland 119.1 31.7 4.9 5.5 Czechoslovakia 75.0 29.4 - 1.3 1.4 Hungary 90.6 28.2 2.1 2.1 I t a l y 56.8 22.4 11.7 9.4 Canada - 15.5 - -U.K. 25.3 14.5 28.3 14.7 Germany 73.7 13.6 6.4 3.1 France 57.6 11.6 1.6 0.6 U.S. 17.1 11.2 9.4 3.8 Benelux 23.2 9.4 4.9 1.6 Other 12.2 12.0 T o t a l 19.7 100 100 Source: Enarson, D,; Ashley, M. J . ; Grzybowski, S. ' Tu b e r c u l o s i s i n Immigrants to Canada. A Study of Present-Day Pa t t e r n s i n R e l a t i o n to Immigration Trends and B i r t h p l a c e . American Reveiw o f R e s p i r a t o r y Disease. 119, Table 4, 13, 1979. 2 2 7o of Foreign-Born i n Canada 7o Cases 3 ) Austria to Hungary 9.5 1 0 . 4 4 ) I t a l y to Others 73.5 4 6 . 2 2 . 3 . 1 S t a t i s t i c a l Trends The A s i a t i c countries of the Philippines, China and India contribute 3 . 3 7 o to the t o t a l number of foreign-born persons i n Canada, y e t ' 2 1 . 2 % of the t o t a l number of cases of tuber-c u l o s i s among the foreign-born i n Canada occur i n t h i s group, i . e . a r a t i o of about 1 : 7 ; Finland to Greece a r a t i o of about 1 : 2 ; Austria to Hungary about 1 : 1 ; I t a l y to Benelux and others 1 . 6 : 1 . There i s no geographic or other association between these countries which have been grouped i n t h i s way for comparative purposes only. In general, immigrants from the more developed countries contribute less to tuber-c u l o s i s s t a t i s t i c s than immigrants o r i g i n a l l y from l e s s developed countries. Active cases of tuberculosis are prevented from admission to Canada by the pre-immigration screening. Nevertheless, immigrants from countries with a high incidence of Pulmonary Tuberculosis contribute d i s -proportionately to s t a t i s t i c s of tuberculosis i n Canada. While s o c i a l factors and r a c i a l s u s c e p t i b i l i t y may c o n t r i b -ute to the higher incidence rate among ce r t a i n immigrant groups, endogenous r e a c t i v a t i o n accounts for most cases. As reported by the American Thoracic Society, 23 reactivations occur i n up to 4.5% of positive tuberculin reactors each year. 2.4 Incidence of Tuberculosis Among Various Immigrant Population  Groups The influence of various immigrant groups on tuberculosis s t a t i s t i c s has been studied extensively. In B r i t a i n , suc-cessive waves of immigrants have entered the country allowing comparative studies to be done. Kess and McDonald studied I r i s h immigrants to L o n d o n . I r i s h immigrants to B r i t a i n had an incidence of Pulmonary Tuberculosis twice that of comparable groups remaining i n Ireland. A susceptible immigrant group from a non-infectious r u r a l environment had entered an i n f e c t i o u s urban environment and a higher rate of disease had r e s u l t e d for the I r i s h immigrants. Table 3, page 21, shows that no immigrant group to Canada had more tuberculosis i n Canada than in the country of o r i g i n . The pre-immigration medical screens out possible active cases. Immigrants to Canada are a pre-selected group. Waves of immigrants to B r i t a i n in the 1950's resulted i n other studies of tuberculosis among immigration groups. (21) Springett et a l studied the incidence of tuberculosis among West Indian immigrants and Asian immigrants resident i n B r i t a i n . Disseminated disease occurred among West Indians shortly a f t e r t h e i r a r r i v a l i n B r i t a i n at a higher incidence 24 than seen i n comparable groups i n t h e i r natural environment i n the West Indies. In contrast, Asians demonstrated more chronic Pulmonary Tuberculosis. Springett concluded that the Asian immigrants had brought the disease with them, whereas the r e l a t i v e l y more susceptible West Indians had been infected with Pulmonary Tuberculosis a f t e r a r r i v a l i n B r i t a i n . The incidence of Pulmonary Tuberculosis among Pakistani immigrants resident i n Bradford, England, was studied by (22) Stevenson who concluded that the higher incidence of tuberculosis among Pakistanis was due to: 1 ) A high prevalence of active tuberculosis i n Pakistan. 2) Overcrowded, inadequate accommodation f a c i l i t -ated the spread of disease among Pakistani immig-rants a f t e r t h e i r a r r i v a l i n England. The incidence among Pakistanis was 30 times the incidence among British-born residents. In B r i t a i n , as i n Canada, some groups of immigrants have a high incidence of tuber-c u l o s i s . Though forming a small proportion of the general population, immigrant groups, such as those from Southeast Asia, contribute disproportionately to tuberculosis s t a t -i s t i c s . In B r i t a i n , f or example, persons born i n Pakistan and India formed 1 7 , of the t o t a l population, yet Pakistani and Indian immigrants resident i n B r i t a i n contributed 9 . 6 7 o (23) of the t o t a l number of cases of tuberculosis i n 1 9 6 0 . 25 2.5 Suspected High Incidence of Pulmonary Tuberculosis Among  Refugee Immigrants Southeast Asia i s an area with a high prevalence of i n f e c t i o n (24) with tuberculosis. Vennema states that 6 6 % of the r u r a l population of Vietnam has p o s i t i v e tuberculin tests i n d i c a t i n g i n f e c t i o n with M. tuberculosis. In contrast, the Canadian population has an estimated 207o p o s i t i v e tuber-(25) c u l i n reactors. The pre-immigration medical screening e f f e c t i v e l y excludes a l l active cases of Pulmonary Tubercul-o s i s . Cases of active Pulmonary Tuberculosis presenting a f t e r a r r i v a l i n Canada would be part of the 1 to 4.5% endogenous reactivations which occur i n any population (26) group infected with M. tuberculosis -The refugee immigrants from Southeast Asia have s i m i l a r i t i e s (27) to the Pakistani immigrants studied by Stevenson i n Bradford, England. The refugee immigrants came from an (28) area where Pulmonary Tuberculosis has a high prevalence. Subsequent to pre-immigration screening, they have been housed i n overcrowded refugee t r a n s i t camps under circum-stances f a c i l i t a t i n g the spread of i n f e c t i o n . After a r r i v a l i n Canada, groups of refugee immigrants ( p a r t i c u l a r l y i n Vancouver) have been l i v i n g i n overcrowded conditions, ( 2 9 ) again f a c i l i t a t i n g the spread of i n f e c t i o n . It i s hypothesized that a number of cases of disease w i l l have occurred due to these circumstances. If i n f e c t i o n has taken place subsequent to the pre-inmiigration screening, then the rescreening program should i d e n t i f y cases of 26 Pulmonary Tuberculosis at the e a r l i e s t stages of the disease, e.g. radiographically at the primary active and minimally active stage of the disease. (See Page 94) 2.6 Summary Immigration s t a t i s t i c s indicate that an increasing percentage of immigrants coming to Canada w i l l originate from Asia. Whereas the incidence of tuberculosis i s declining i n the general population i n Canada, some groups of immigrants ( p a r t i c u l a r l y from Southeast Asia) have a high incidence of tuberculosis. Refugee immigrants may demonstrate high incidence rates of Pulmonary Tuberculosis due to i n f e c t i o n becoming apparent subsequent to the pre-immigration screening. 27 3. Epidemiology of Tuberculosis 3.1 Mortality The dramatic decline i n deaths due to tuberculosis i n Canada and the United States since 1940 i s shown by Figure 4 (Page 28). This decline commenced before the introduction of ef-f e c t i v e antimicrobials which accelerated the downward trend of the death rate. In 1978, the mortality rate for tuber-c u l o s i s was 1.1 per 100,000 for Canada. The comparative figure was 1.4 per 100,000 for the United S t a t e s . ( 3 0 ^ The r a t i o between mortality rate and incidence rate of new i n -( 31) fections has been 1:10. In Canada 31,375 cases of active tuberculosis were recorded between 1970 and 1977; 2,971 deaths due to tuberculosis ( 32) were reported i n the same period. Diagnosis of tubercul-osis a f t e r death i n f l a t e d the mortality rate for tuberculosis F i f t y percent of deaths reported due to tuberculosis did (33) not have an ante mortem diagnosis of tuberculosis. ! 3.2 Causes of Death Due to Tuberculosis In c h i l d r e n , tuberculous meningitis i s the major cause of death. In adults, post-primary Pulmonary Tuberculosis (33) i s the most frequently reported cause of death. 3.3 Cohort Analysis of Tuberculosis Mortality (34) Grzybowski and Marr analyzed cohort patterns of mortal-i t y rates for males and females i n Ontario from 1881 - 1961. 28 F i g u r e 4 T u b e r c u l o s i s M o r t a l i t y Per 100,000 Population Canada and United S t a t e s 1940-1975 1960 1965 1970 1975 Source: Grzybowski, S.^ 3 0^ 'Epidemiology and the Role o f B.C.G.' C l i n i c s i n Chest Medicine. 1.2, 176, 1980. 29 Cohort patterns revealed a rapid r i s e of mortality rates i n childhood with a peak around 25 years of age. The rate of decline of mortality f o r the female cohorts was steeper than for male cohorts. C l i n i c a l l y , Pulmonary Tuberculosis has been more ra p i d l y f a t a l for young women than young men. Grzybowski and Marr stated: (1) Post-primary tuberculosis was more common among young adults, with the peak mortality rate f o r each cohort occurring between 20 and 29 years. (2) The factors leading to high mortality rates among young adults remained l i a b i l i t i e s for each i n d i v i d u a l f o r the l i f e span of the cohort. The mortality rates for successive cohorts, although d e c l i n i n g , demonstrated (35) the same pattern over the years. According to Grzybowski and Marr, the declining mortality rates were due to: (1) Declining r i s k of i n f e c t i o n (2) Progressive increase i n natural resistance (3) Improved standard of l i v i n g , p a r t i c u l a r l y n u t r i t i o n (4) Tuberculosis control measures. Tuberculosis has become a disease of older men. The i n c i d -ence of disease i n the e l d e r l y represents a residuum of higher rates of i n f e c t i o n experienced i n e a r l i e r l i f e . 3.4 Tuberculosis Morbidity With the decline i n tuberculosis mortality rates, the 30 incidence rate has become a more sensitive indicator for (36) tuberculosis i n developed countries. The d e c l i n i n g incidence rate for the Unites States and Canada between 1950 and 1977 i s shown by Figure 5 (page 31). The annual rate of decline i s about 570. If t h i s decline continues, 2,000 new active cases of tuberculosis w i l l be diagnosed i n Canada i n 1990 and only 1,200 cases i n the year 2000. 3.5 Comparisons With Other Countries The wide v a r i a t i o n i n incidence rates that occurs between countries i s graphically displayed by Figure 6, page 32. The developed countries generally have a l e s s e r incidence rate. 3.6 Various Population Groups i n Canada ; While the o v e r a l l incidence rate was 16.1 / 100,00 i n 1972, Figure 7 (Page 34) displays the d i s p a r i t y between various population groups i n Canada. Eskimos, Canadian Indians, and Asian immigrants have incidence rates of Pulmonary Tuberculois several times the rate occurring among Canadian-born Caucasians. G r z y b o w s k i ^ ^ demonstrated that socio-economic conditions were not the only factors involved i n higher incidence rates. Figure 8 ,( Page 35) shows that rates among native Indians are highest where contact with white s e t t l e r s occurred most recently. For a susceptible population (the native Indians), the l a t e r the contact with the tubercle b a c i l l u s (from the white s e t t l e r s ) the 31 Source: Grzybowski, S.^30^ Epidemiology and the Role of B.C.G. C l i n i c s in Chest Medicine. 1.2, 179, 1980. Figure 6 U.S.A. Canada Cuba 1972 Taiwan S r i Lanka Equador Venezuela Colombia Hong Kong P h i l i p p i n e s • New cases of a c t i v e t u b e r c u l o s i s per 100,000 popula t i o n in USA Canada and s e l e c t e d developing c o u n t r i e s , 1973. 14.8 16.1 14.5 39.4 49.5 49.5 53.6 89.0 LO S3 196.0 328.3 Source: Grzybowski, S. 'Evaluation of the T u b e r c u l o s i s Problem and Control Measures i n Canada'. Graph 3, Page 67 33 higher the current incidence rate. G r i g g ^ 1 ^ postulated the gradual development of resistance i n a previously tuber-c u l o s i s - f r e e population. Individuals more susceptible to tuberculosis die o f f . The natural s e l e c t i o n of geno-types with greater resistance to M. tuberculosis would r e s u l t i n the development of a population less susceptible to tuberculosis. According to Grigg's hypothesis, white people have a longer h i s t o r y of exposure to tuberculosis and are more r e s i s t a n t ; native Indians, Eskimos, and Asians have a shorter history of exposure to tuberculosis and are r e l a t i v e l y more susceptible. 3.7 Reactivation of Cases of Inactive Pulmonary Tuberculosis (^  2) According to Grzybowski et a l , 10 to 15% of cases of active tuberculosis develop by r e a c t i v a t i o n i n patients recovered from previous active tuberculosis. Two factors a f f e c t r e a c t i v a t i o n . 1) Antimicrobial therapy. The r e a c t i v a t i o n rate i s about 0.2% a f t e r adequate antimicrobial therapy. 2) Time lapsed since recovery. The greatest r i s k of r e a c t i v a t i o n occurs i n the f i r s t few years following recovery from active tuberculosis. In the pre-antimicrobial era, about 4 . 4 7 o would relapse each year. A f t e r so-called benign primary tuberculosis which may heal without overt signs of disease, endogenous r e a c t i v a t i o n occurs i n about 0.55% of cases per annum. F i a u r e 7 Canadian Born Foreign Born Registered Indians Eskimos Average annual incidence r a t e s of a c t i v e t u b e r c u l o s i s ( a l l forms) per 100,000 popula t i o n among fou r p o p u l a t i o n groups i n Canada f o r 1970-1974. 15.7 28.4 149.9 469.3 Source: Grzybowski, sS3^ .'Evaluation of the T u b e r c u l o s i s Problem and Control Measures i n Canada' Compiled from Table XVIII Page 57 35 Figure 8 R A T E P E R H U N D R E D T H 0 U S A N D Average Annual Incidence (1970-74) of Active Tuberculosis Among Registered Indians in Various Regions of Canada Per 100,000 Population. 280 240 200 160 120 80 40 Region Eastern Century F i r s t 17th Settled P a c i f i c Source: 18th P r a i r i e 19th Northern 20th (39) Grzybowskl, S/ 'Epidemiology and the Role of B.C.G.' C l i n i c s i n Chest Medicine. 1.2, 180, 1980. 3 6 3 . 8 Age and" Sex-Specific Rates of Tuberculosis The average incidence of tuberculosis amongst males and females i s shown by Figure 9 , Page 3 7 . Up to f i v e years of age, rates are low; and about equal for the sexes to the 2 5 to 3 4 - y e a r age bracket; subsequently, tuberculosis i s predominantly a disease of males. 3 . 9 Importance of B a c t e r i o l o g i c a l Confirmation According to Grzybowski, chest x-ray should be consid-ered a screening test f o r tuberculosis. The diagnosis should be confirmed with the b a c t e r i o l o g i c a l demonstration of M. tuberculosis to enable the rates of tuberculosis to be compared i n t e r n a t i o n a l l y . In Canada, 8 0 7 o of cases of tuberculosis have b a c t e r i o l o g i c a l confirmation of the diagnosis. 3 . 1 0 Fate of People with Pulmonary Tuberculosis A p i c t o r i a l representation of the fate of persons with bacteriologically-confirmed tuberculosis i s shown by Figure 1 0 (Page 3 8 ) . G r z y b o w s k i ^ , analyzing current data and data from the p r e - a n t i b i o t i c era, demonstrated that with adequate chemotherapy 9 2 7 , of active cases of Pulmonary Tuberculosis were cured. The 3 7 . of chronic cases and 5 7 0 of deaths were not true f a i l u r e s of antimicrobial therapy; rather, they were f a i l u r e s of compliance and f a i l u r e s of diagnosis. That i n d i v i d u a l i z e d antimicobial therapy has d i s t i n c t advantages i s shown by Figure 1 0 (Page 3 8 ) . In undeveloped countries, mass treatment has also proved bene-f i n c i a l . Up to 3 0 7 , of bacteriologically-proven cases of 37 F i g u r e 9 Average Annual Rate of A c t i v e T u b e r c u l o s i s ( a l l forms) Per 100,000 Population i n Canada 1970-1976. 70 R A T E P E R H U N D R E D T H 0 U S A N D 60 50 40 30 J 20 10 / Female 0-14 Source: 15-24 25-34 35-44 45-54 55-64 65+ Age Groups i n years Grzybowski, S.^ 4 4) 'Evaluation of the T u b e r c u l o s i s Problem and Control Measures i n Canada'. Graph 4, Page 68 3 8 Figure 1 0 Fate of Cases of Pulmonary Tuberculosis Confirmed B a c t e r i o l o g i c a l l y A f t e r Two Years Under Different Treatment Regimens Deceased Chronic Cured 5% 3% 92% Deceased Chronic Cured 1 0 7 o 2 5 7 . 6 5 7 o Deceased Chronic Cured 4 0 7 o 3 0 7 o 3 0 7 o Individual Chemotherapy Mass Chemotherapy No Chemotherapy Source: Grzybowski, S. * 'Epidemiology and the Role of B.C.G." C l i n i c s i n Chest Medicine. 1 , 2 , 1 8 4 , 1 9 8 0 . 3 9 tuberculosis heal spontaneously but, following spontaneous healing, a substantial number of cases subsequently relapse 3.11 Summary Mor t a l i t y rates f o r tuberculosis i n Canada declined a f t e r 1 9 4 0 . Up to 5 0 7 o of persons dying of tuberculosis are diag-nosed a f t e r death. Tuberculous meningitis i s the major cause of death i n ch i l d r e n , whereas Pulmonary Tuberculosis i s most common i n adults. F a l l i n g mortality rates are due to i ) d e c l i n i n g r i s k s of i n f e c t i o n , i i ) progressive increase i n natural resistance, i i i ) improved standards of l i v i n g , p a r t i c u l a r l y nu-t r i t i o n , and iv) tuberculosis-control measures. With d e c l i n i n g mortality rates, tuberculosis morbidity has become a more sensi t i v e i n d i c a t o r of the disease. Tuberculosis morbidity s t a t i s t i c s are a more sensi t i v e i n d i c a t o r of disease than mortality s t a t i s t i c s . Endog-enous r e a c t i v a t i o n i s a major cause of new active cases of tuberculosis i n Canada. Comparisons of tuberculosis s t a t i s t i c s should be of b a c t e r i o l o g i c a l l y proven cases only. While spontaneous healing of tuberculosis may occur, relapses w i l l follow. Relapses are s i g n i f i c a n t l y fewer following adequate antimicrobial therapy. 40 4. General Description of Tuberculosis 4.1 General In his discussion of 'The Diagnosis of Tuberculosis', Bailey said, "For most diseases, i n f e c t i o n and disease are synonymous ." Individuals infected with the tub-ercle b a c i l l u s may have a positive reaction to a tuberculin skin t e s t , but most infected individuals w i l l not develop the active disease known as tuberculosis. Defense mechan-isms, h y p e r s e n s i t i v i t y , and c e l l u l a r immunity act to prevent i n f e c t i o n from becoming active disease. Yet only infected i n d i v i d u a l s can become diseased, and active disease may follow i n f e c t i o n at any time within the l i f e span of the infected i n d i v i d u a l . 4.2 Screening for Infection and Disease The purposes of the refugee immigrant rescreening program were 1) the diagnosis of active tuberculosis and 2) the i d e n t i f i c a t i o n of refugee immigrants infected with M. tuberculosis, therefore having the potential for future development of active disease. The intention was to o f f e r antimicrobial therapy to i n d i v -iduals with "active disease" and chemoprophylaxis to those persons c l a s s i f i e d as infected, i . e . with inactive disease, thereby preventing active disease from developing. Indiv-idual and public health benefits would follow. The person 41 with active tuberculosis received i n d i v i d u a l i z e d treatment. The disease was cured and a chain of transmission disrupted. The "infected" or i n d i v i d u a l with inactive disease received chemoprophylaxis, preventing active tuberculosis from devel-oping. A p o t e n t i a l chain of transmission was not allowed to develop. 4.3 Diagnosis of Active Disease Tuberculosis ranges from so-called "benign primary a c t i v e " , through "minimally a c t i v e " , "moderately active", and "ad-vanced a c t i v e " disease. F i n a l diagnosis of t h i s p a r t i c u l a r disease depends on b a c t e r i o l o g i c a l demonstration of M. tuberculosis. The b a c t e r i o l o g i c a l i d e n t i f i c a t i o n of M. tuberculosis i s r a r e l y incorrect. It i s possible to ident-i f y the tubercle b a c i l l u s i n a l l cases of tuberculosis , even i n the 6 to 8 weeks during which the tubercle b a c i l l u s i s e stablishing i t s e l f i n the l u n g . ^ ^ P r a c t i c a l l y , t h i s i s not f e a s i b l e and c e r t a i n l y becomes p r o b a b i l i t y with diagnosis r e s t i n g upon tuberculin skin t e s t i n g , radiographic evidence, b a c t e r i o l o g i c a l examination, and c l i n i c a l acumen. 4.4 Symptoms of Tuberculosis Primary tuberculosis may be asymptomatic and usually occurs (47) i n c h ildren, — les frequently i n adults. Pulmonary complaints of chronic cough with production of purulent sputum, p l e u r i t i c chest pain, and acute respiratory d i s t r e s s are a l l non-specific and open to misinterpretation. Constit-utional complaints of fever, lassitude, malaise, anorexia, 42 weight l o s s , and easy fatigue occur more frequently than pulmonary complaints. More advanced cases of Pulmonary Tuberculosis present with a combination of pulmonary and non-pulmonary symptoms with the diagnosis being made by a combination of physical examination, chest x-ray, and, f i n a l l y , b a c t e r i o l o g i c a l i d e n t i f i c a t i o n of M. tuberculosis. 4.5 Tuberculin Test Although reproducible i n any given patient, the reaction to P u r i f i e d Protein Derivative (P.P.D.) i s a b i o l o g i c a l phenomenon; l i k e many such phenomena, i n a population of reactors the size of the reaction follows a normal frequency d i s t r i b u t i o n c u r v e . ' ' The d i s t r i b u t i o n curves from several h o s p i t a l populations were so s i m i l a r that they could be superimposed on one another. Large studies of tuberculous patients have confirmed that few would have reactions less than 5 mm i n size and, i n i t i a l l y , t h i s was the accepted standard for the lower l i m i t of a posit i v e reaction. P u r i f i e d Protein Derivative (P.P.D.) / • \ The use of PPD-S w i l l not d i f f e r e n t i a t e c l e a r l y between sub-groups infected with atypical mycobateria. In many t r o p i c a l climates, large segments of the populations have skin test h y p e r s e n s i t i v i t y to environmental mycobacteria. Footnote: ( i ) PPD-S - p u r i f i e d protein d e r i v a t i v e stand-ardized from M. tuberculosis. 43 This h y p e r s e n s i t i v i t y produces cross-reactions with PPD which i s manifested by small-sized tuberculin reactions. Keck, St. John, Daniel et a l ^ " ^ investigated the skin reaction to intermediate-strength PPD i n two v i l l a g e s i n B o l i v i a (Figure 11, Page 44). The responses from one v i l l a g (Coroico) formed a frequency curve with a bell-shaped pat-tern. Individuals with M. tuberculosis infe c t i o n s were i d e n t i f i e d by po s i t i v e reactions with a mean and a mode of 18 mm. In contrast, the frequency curve from the other v i l l a g e (Suapi) resulted from a large number of reactors of small s i z e . These small reactions were presumed to represent c r o s s - r e a c t i v i t y to antigens of other mycobacteria Recognition of the cross-reaction between antigens of atyp-i c a l mycobacteria led the American Thoracic Society to recommend the adoption of 10 mm as the minimal size of (51) induration of a pos i t i v e skin tes t . In many populations, i n f e c t i o n with a t y p i c a l mycobacteria i s uncommon; most small tuberculin reactions represent true p o s i t i v e . r e a c -t i o n s , i n d i c a t i n g i n f e c t i o n with M. tuberculosis. To over-come the problem of c r o s s - r e a c t i v i t y , PPD's from other species of mycobacteria have been prepared by the United (52) States Public Health Laboratory. These have subscripts to d i s t i n g u i s h them from PPD-S which i s the tub e r c u l i n protein derivative from M. tuberculosis, e.g. PPD-B from the Battey b a c i l l u s (M. i n t r a c e l l u l a r ) ; PPD-G, Gause s t r a i n (M. scrofulaceum); and PPD-Y, yellow b a c i l l u s (M. k a n s a s i i ) . Figure 11 Comparison of Skin S e n s i t i v i t y to Intermediate Strength P.P.D. i n Two V i l l a g e s i n B o l i v i a 0 F P 0 S I T I V E R E A C T 0 R S 8 12 16 20 24 28 32 8 12 16 20 24 32 Source: Reaction S i z e i n mm Keck, C. W., St. John, R. K., D a n i e l , T. M. ^ 'Tuberculosis i n the Yungas Area of B o l i v i a 1 Health S e r v i c e Report 88, 503, 1973. 45 In epidemiological studies, the skin reactions to the pur-i f i e d protein derivative (PPD) of a p a r t i c u l a r s t r a i n of mycobacteria, e.g. PPD-B for M. i n t r a c e l l u l a r e , have been used to estimate the prevalence of i n f e c t i o n of that s t r a i n of mycobacteria i n the population studied. Tuberculin skin tests using PPD-B, PPD-G, and PPD-Y are not s u f f i c i e n t l y s e n s i t i v e or s p e c i f i c to be useful as diagn o s i t i c tools i n the treatment of the in d i v i d u a l suffering from a mycobacter-i a l i n f e c t i o n . Cross-reactions occur frequently; 55-807, of persons with documented M. kansasii disease have larger skin reactions to PPD-S than PPD-Y. ( 5 3 , 5 4 ) 4.6 Booster Phenomenon Repeated skin t e s t i n g with PPD may lead to an increase i n the size of the tuberculin-positive reaction due to a boosted immunological response. ^  5 5 ' 5 d ^ Individuals s e n s i t i z e d by en-vironmental, i . e . a t y p i c a l mycobacteria, may demonstrate an increase i n the size of the tuberculin skin reaction to PPD-S. A boosted response may cause confusion but w i l l not produce a p o s i t i v e ( i . e . greater than 10 mm of skin induration) tub-e r c u l i n skin reaction i n a person who has not been infected with M. tuberculosis. • ( 5 7 ) Holden, Dubin, and Diamond reported that persons with recently diagnosed tuberculosis may have negative skin reactions. Up to 307» of patients with previously untreated tuberculosis are reported as having negative skin reactions ( 58) to t e s t i n g with 5 units of PPD-S . Investigations on tuberculin r e a c t i v i t y were o r i g i n a l l y performed on the-, c h r o n i c a l l y i l l ; l a t e r studies have used newly-diagnosed 46 cases of tuberculosis. Some se r i o u s l y i l l patients have negative skin responses early i n the course of t h e i r disease as the diesease becomes chronic, a tuberculin skin test produces a p o s i t i v e response. The tuberculin skin test i s more than a simple in d i c a t o r of past or present tuberculous i n f e c t i o n . Erroneous i n f o r -mation i s obtained i f skin responses to tuberculin skin (59) tests are not interpreted c r i t i c a l l y . The tuberculin reaction indicates the prevalence of i n f e c -t i o n with eit h e r M. tuberculosis or at y p i c a l mycobacteria. For the i n d i v i d u a l , the tuberculin test suggests but does not confirm past or present tuberculosis i n f e c t i o n . 4.7 Small Positive Reactions to the Tuberculin Skin Test Where a t y p i c a l mycobacteria are not prevalent i n the environ-ment, smaller reactions than the accepted empirical 10 mms of induration also represent i n f e c t i o n with M. tuberculosis. Grzybowski et a l ^ ^ suggest that children with smaller tuberculin reactions have received lower i n f e c t i n g doses of b a c i l l i , and that the average size of tuberculin skin reaction increases with increasing age up to the f i f t h decade of l i f e and then gradually decreases i n the e l d e r l y . This correlates with repeated infections by tubercle b a c i l l i r e s u l t i n g i n larger skin reactions to tuberculin t e s t i n g . The e l d e r l y have diminished r e a c t i v i t y of the skin. In contrast to smaller tuberculin reactions, i n d i v i d u a l s with larger skin reactions have an increased incidence of active tuberculosis.(61) 47 4.8 Tuberculin Test Amongst the Refugee Immigrants Table 4 (Page 48) gives the age breakdown and size of skin induration of the tuberculin tests for the refugee immig-rants skin tested i n Vancouver by the Refugee Resettlement Program up to June 25, 1980. Figure 12 (Page 49) i s a histogram of those tuberculin reactions. The t y p i c a l b e l l -shaped frequency pattern i s displayed. When a p o s i t i v e response i s defined empirically as 10 mm of skin induration, 43.5% of the refugee immigrants have a negative tuberculin skin t e s t . Typical mycobacteria are not common i n areas where i n f e c t i o n and disease with M. tuberculosis are serious problems. In the absence of skin reactions due to atypical mycobacteria, p o s i t i v e reactions 5 mm's and up are ind i c a t i v e of i n f e c t i o n with M. tuberculosis. From Table 4 (Page 48) 33 refugees (437.) had intermediate reactions between 5 mm and 9 mm. Of these 33, 22 were under 35 years of age and would q u a l i f y f o r chemoprophylaxis. Various investigators have reported on the pos i t i v e c o r r e l a t i o n between the size of the tuber-c u l i n reaction and the r i s k of actual tuberculosis. 22 Nevertheless, t h i s extra -J^J, i . e . 2.97., are infected with M. tuberculosis and should have been considered for chemo-prophylaxis. • ' \ 4.9 Summary Infect ion with M. tuberculosis may not lead to acute active TABLE 4 Tuberculin Test Response i n 762 Refugee Immigrants Size of Skin Induration to 5 T.U. PPD-S mms Age (yrs.) 0-2 3-4 5-6 7-8 9-10 11-12 13-14 15-16 17-18 19-20 21-22 23-24 25-26 27-28 29-30 30+ 0-4 64 1 2 3 2 8 2 1 5-9 59 2 2 1 3 1 3 2 1 1 1 10-14 47 1 4 2 7 5 8 10 6 2 4 3 1 15-24 70 4 2 8 16 20 23 23 25 21 10 2 6 2 2 25-44 33 2 3 2 16 16 26 29 13 18 16 5 6 2 3 45-64 15 1 3 8 8 7 7 8 8 3 3 65+ 3 1 1 2 1 Total No. Refugees Tuberculin Tested 762 291 9 11 18 4 46 55 68 82 54 52 35 10 18 2 2 5 100% 38 1.2 1.4 2.4 D.5 D.O 7.2 9 10.8 7.1 7.0 4.6 1.3 2.4 0.2 0.2 0.6 Source: Division of Tuberculosis Control, Vancouver Records of Refugee Immigrants Tuberculin Skin Tested by the Refugee Resettlement Program, Vancouver, B. C. 49 P E R C E N T A G E 0 F R E A C T 0 R S 40 Figure 12 Histogram of Tuberculin Reactions of 763 Refugee Immigrants Skin Tested with 5 T.U. P.P.D in Vancouver, B.C., by June, 1980 35 30 25 20 15 10 0-2 3-4 5-6 7-8 9_io n-12 13-14 15-16 17-18 19-20 21-22 23-24 25-26 27-28 Size of Induration in mm Source: Compiled from Table 4 (Page 48) 50 disease. Diagnosis of Pulmonary Tuberculosis i s made by a combination of symptoms, signs, laboratory investigations, and chest x-ray; b a c t e r i o l o g i c a l demonstration of M. tuber- c u l o s i s i s the f i n a l confirmation. Unfortunately, symptoms with tuberculosis are often non-specific and misinterpreted. C r i t i c a l i n t e r p r e t a t i o n of tuberculin skin tests i s required While a p o s i t i v e tuberculin skin t e s t may indicate past i n f e c t i o n with M. tuberculosis cross-reactions occur a f t e r i n f e c t i o n with a t y p i c a l mycobacteria. Among refugee immig-rants, and p a r t i c u l a r l y refugee immigrant ch i l d r e n , tuber-c u l i n reactions measuring less than 10 mm of induration may s t i l l i ndicate past i n f e c t i o n with M. tuberculosis. 51 5. Control Measures 5.1 H i s t o r i c a l Approach The Tuberculosis Sanitarium In the early 1900's, Pulmonary Tuberculosis was a prevalent disease with a high mortality rate for young adults. The tuberculosis sanitarium aimed at i s o l a t i n g the i n f e c t i v e i n d i v i d u a l and gi v i n g that i n d i v i d u a l an opportunity to recover i n an atmosphere encouraging rest with good food a n d f r e s h a i r . Antimicrobial therapy has resulted i n the V closure of most s a n i t a r i a . Mass Screening Mass miniature x-ray surveys are no longer used for community-wide surveys. The present incidence of disease i n Canada i s so low that the cost of finding a case by t h i s method has become p r o h i b i t i v e . Mass screening i s occasionally practiced i n selected high-risk groups. 5.2 H o s p i t a l i z a t i o n Hospital admissions account for 707o of the costs of tuber-(63) c u l o s i s control programs. According to Grzybowski, ind i v i d u a l s expectorating large numbers of mycobacteria should have short-stay admissions to hospitals u n t i l non-i n f e c t i v e . Non-compliance (one of the main reasons for h o s p i t a l admissions) could be overcome by completely monit-ored out-patient programs u t i l i z i n g drugs such as rifampin and i s o n i a z i d on intermittent short courses. 52 5.3 Hospital Employees Hospital employees are at special r i s k of Pulmonary Tuber-c u l o s i s . Post mortem diagnosis of tuberculosis accounts for 507o of deaths recorded due to t u b e r c u l o s i s . ^ " ^ The number of undiagnosed cases of tuberculosis among hospital in-patients i s unknown since post mortem examination i s performed on only one t h i r d of patients dying i n h o s p i t a l . Each undiagnosed case of tuberculosis i s a hazard to the h o s p i t a l s t a f f . E f f e c t i v e control measures fo r employees i n many Canadian hospitals comprise: 1) Tuberculin t e s t ; i f negative, B.C.G. i s given 2) I n i t i a l chest x-rays, and 3) Subsequent chest x-ray on exposure to an index case with sputum containing M. tuberculosis. 5.4 Select Groups C i v i l servants, food handlers, teachers, hospital employees, mental patients, and inmates of j a i l s or penitentiaries form select groups which are screened for tuberculosis. The usual r a t i o n a l e f o r such special screening i s high prevalence of Pulmonary Tuberculosis as occurs with j a i l populations or increased public health hazards, e.g. with school teachers. Chest x-ray, eit h e r f u l l - s i z e or mass miniature radiography, i s the most common method of screening. 5.5 Public Health Programs Contacts of cases of active tuberculosis are given tuberculin skin t e s t s . Positive reactors are followed up with chest 53 x-rays. This method has demonstrated rates of i n f e c t i o n J ( and disease are highest among contacts of index cases with sputum smears p o s i t i v e f o r M. tuberculosis. Follow-up of contacts has been an e f f e c t i v e control method. 5.6 D i v i s i o n of Tuberculosis Control Chest c l i n i c s of the D i v i s i o n of Tuberculosis Control act as r e f e r r a l centres for private physicians and o f f e r ambul-atory treatment centres f o r known cases of Pulmonary Tuber-c u l o s i s . Follow-up of high r i s k patients by chest c l i n i c s increases active case-finding. The D i v i s i o n of Tubercul-osis Control i n B r i t i s h Columbia has the o v e r a l l responsib-i l i t y f or public health programs and the general supervision of diagnostic and treatment a c t i v i t i e s . 5.7 The Medical Profession and Tuberculosis Control According to Grzybowski, a major part of tuberculosis control f a l l s upon physicians, many of whom have had inadequate t r a i n i n g regarding tuberculosis. The s t a t i s t i c s of post mortem diagnosis of Pulmonary Tuberculosis support Grzybowski's statement that physicians should be taught to "Think Tubercul-o s i s " ( p a r t i c u l a r l y those physicians i n contact with high-r i s k groups such as refugee i m m i g r a n t s . ) ^ 5.8 Immigration Allowing for the preselection that occurs during the pre immigration medical screening of prospective immigrants, 54 landed immigrants display an incidence rate of Pulmonary Tuberculosis s i m i l a r to that of the population from which they o r i g i n a t e . The population of some areas i n Asia, e.g. India and Vietnam, have a high prevalence of Pulmonary Tuberculosis. Immigrants from high prevalence areas contrib-ute disproportionately to tuberculosis s t a t i s t i c s i n B r i t i s h Columbia even though pre-immigration medical screening excludes i n d i v i d u a l s with active tuberculosis. While the incidence rate of Pulmonary Tuberculosis i s high among some groups of Asian immigrants, the actual burden of d i s -ease i s low; e.g. the number of cases of Pulmonary Tuber-c u l o s i s occurring i n Asian immigrants to B r i t i s h Columbia between 1976 and 1978 averaged f i v e cases per year. As Grzybowski stated, i f involved physicians were taught to "Think Tuberculosis", the disease would not be a problem among immigrants from high-prevalence areas. 5.9 V i s i t o r s and Students Pulmonary Tuberculosis occurs among v i s i t o r s on long stay permits and students on special visas who are not obliged to undergo medical screening p r i o r to coming to Canada. A l l persons coming, to Canada for an extended period (e.g. more than one year) should have a tuberculin skin test followed by chest X-ray of positive reactors. This would minimize the public health hazards from unrecognized acute Pulmonary Tuberculosis associated with students and long-stay v i s i t o r s . 55 5.10 B.C.G. i The province of Quebec issues 757o of a l l the B.C.G. immun-iza t i o n s i n Canada. The use of B.C.G. for selected high-r i s k populations i s j u s t i f i e d even though controversy exists as to the e f f i c a c y of B.C.G. ( 6 8 ) 5.11 Chemoprophylaxis In developed countries, most c l i n i c a l cases of tuberculosis develop i n persons who have harboured " i n f e c t i o n " i n a dormant phase fo r an extended period of time. Preventive treatment, i n the form of chemoprophylaxis, benefits the ind i v i d u a l by preventing disease and the public by prevent-ing transmission. The introduction of i s o n i a z i d (INH) i n 1952 provided a preventive treatment for tuberculosis which was safe, inex-pensive, and b a c t e r i c i d a l when given o r a l l y . Large-scale t r i a l s i n the U.S.A. led the American Thoracic Society to recommend the use of i s o n i a z i d f o r the prevention of t u b e r c u l o s i s . ^ ^ Decrease i n morbidity follows adequate therapy with i s o n i a z i d immediately and i n subsequent years. Protection occurs even though- the tuberculin t e s t may remain p o s i t i v e . According to Hoeprich's definition of chemoprophylaxis (page 1 2 ) / 7 0 ? i s o n i a z i d i s single drug therapy for tuberculosis i n f e c t i o n . While the treatment might occasionally f a i l f o r b i o l o g i c a l reasons, most f a i l u r e s are due to non-compliance. 56 5.11.1 Drug Resistance Cases of drug resistance to i s o n i a z i d have been r e p o r t e d . ^ About 107o of refugee immigrants may have i s o n i a z i d - r e s i s t a n t ( 72) mycobacterial i n f e c t i o n . Eidus, Jessamine, Herschfield, (73) and Helbecque reviewed drug-resistant mycobacteria y reported i n Canada and commented on the high prevalence of primary drug resistance noted amongst immigrants. ( 7 4 ) Cheung made s i m i l a r observations. Schiffman, Ashkar, Bishop, and C l e a r l y f o u n d that resistance to i s o n i a z i d and to ethambutol was increasing, whereas resistance to para-amino-salicylic a c i d was decreasing. Kbpanoff et a ^ ( 7 6 ) ^ ^ n a S U r v e y conducted by the Centre f o r Disease Control (C.D.C.) noted that Asians had the highest rate of drug-resistance, younger patients having s i g n i f i c a n t l y higher resistance rates than older patients. Byrd, Fisk, ( 7 7 ) Glover, and Wilder noted resistance to i s o n i a z i d at a rate of 5870 among 73 m i l i t a r y dependents immigrating to the United States with tuberculosis. In 1953, i t was shown that i s o n i a z i d - r e s i s t a n t mycobacteria have less virulence for guinea pigs than t h e i r wild-parental (78) organisms . Is o n i a z i d resistance i s a p o t e n t i a l problem. However, i s o n i a z i d i s e f f e c t i v e and the development of drug-resistance disease following adequate chemoprophylaxis i s u n l i k e l y , p a r t i c u l a r y with the lowered virulence demon-strated by i s o n i a z i d - r e s i s t a n t mycobacteria. 57 5.12 Use of Isoniazid Chemoprophylaxis with i s o n i a z i d i s j u s t i f i e d only i f the ri s k s of adverse e f f e c t s are less than the r i s k of developing ( 79) tuberculosis. Such use i s usually r e s t r i c t e d to i n d i v i d -uals below the age of 35 years with a po s i t i v e tuberculin r e a c t i o n greater than 10 mm skin induration. Individuals with a po s i t i v e response to tuberculin test between 5 and 10 mm should also be considered f o r treatment, p a r t i c u l a r l y i n places where a t y p i c a l mycobacterial i n f e c t i o n s are un-common. 5.13 Negative Tuberculin Skin Reactors Children who have been i n contact with a smear-positive index case, who have not yet converted from a negative to a p o s i t i v e tuberculin t e s t , are at r i s k of developing tuber-c u l o s i s . Among refugee immigrants, children with a negative tuberculin test should have the skin test redone within one month. I f the r e - t e s t r e s u l t i s negative, i n f e c t i o n with M. tuberculosis i s u n l i k e l y to have occurred. 5.14 Risk of Adverse Reactions (80) (81) Comstock and Edwards and Moulding discuss the r i s k of adverse e f f e c t s with i s o n i a z i d . For persons over 35 years of age, the r i s k s are greater and a c l i n i c a l d e cision must be made to balance the benefit against the r i s k of adverse reaction. Isoniazid i s contraindicated for persons with previous hepatic i n j u r y due to i s o n i a z i d , or with 58 (82) acute l i v e r damage from any cause. Other conditions r e q u i r i n g s p e c i a l medical attention before chemoprophylaxis can be safely prescribed are pregnancy, d a i l y alcohol con-sumption, chronic l i v e r disease, individuals on diphenyl-hydantoin, and i n d i v i d u a l s on concurrent medications where "> (83) possible interactions might occur. Among healthy young people, adverse reactions are uncommon. The most serious e f f e c t i s isoniazid-induced h e p a t i t i s which occurs i n less than 17,^^ of r e c i p i e n t s , arid increases (85) with age as shown by Riska , Figure 13 (Page 59). Hepatic dysfunction occurs more frequently. According (86) to Farer , 10 to 207, of a l l persons receiving i s o n i a z i d w i l l experience transient elevation i n hepatic enzyme l e v e l s while taking the drug. The mechanism of isoniazid-induced hepatic dysfunction i s unknown. If treatment continues i n the face of d e f i n i t e symptoms of l i v e r disease, f a t a l (88) fulminant h e p a t i t i s may occur. Black reported on 24 such f a t a l cases i n the world's l i t e r a t u r e . P r i o r to ison-i a z i d chemoprophylaxis, chest x-ray to exclude active Pul-monary Tuberculosis i s mandatory. A l l e r g i c reaction to i s o n i a z i d must be excluded. A previous adequate course of i s o n i a z i d i s a contraindication to further therapy. Other drug usage (including alcohol) must be discussed to prevent possible interactions with i s o n i a z i d . ^ 59 F i g u r e 13 Incidence o f H e p a t i t i s with Increasing Age 8 A N D 2 1 H 35 35-44 45-54 55 y r s Age i n Years Source: M o d i f i e d a f t e r N. R i s k a ^ 7 ^ ' H e p a t i t i s Cases i n I s o n i a z i d Treated Groups and i n a Control Group'. B u l l e t i n I.U.A.T. 51 (1) 207, 1976. 6 0 5 . 1 5 Dose and Duration of Chemoprophylaxis The adult dosage i s 3 0 0 mg o r a l l y once per day. The e a r l i e r months of therapy are more b e n e f i c i a l than the l a t e r months. According to Farer, consideration of the e f f i c a c y , adverse reaction, patient compliance, and cost of i s o n i a z i d chemoprophylaxis sets the optimal duration i n the 6 to 1 2 month range. A proportionately higher percentage are pro-tected with the longer course; maximum protection occurs when the duration of therapy i s about 1 2 months. 5 . 1 6 Precautions (91) Farer has recommended monthly follow-up to protect against adverse reactions. Routine biochemical monitoring of l i v e r function has proved valueless i n preventing ison-iazd-induced h e p a t i t i s . 5 . 1 7 Alternative Drugs Isoniazid i s the only true chemoprophylactic drug a v a i l a b l e . . Infection with i s o n i a z i d - r e s i s t a n t mycobacteria i s a problem. About 1 0 7 o of the strains of M. tuberculosis i s o l a t e d from ( 9 2 ) Asian refugees are i s o n i a z i d - r e s i s t a n t . For chemopro-phylaxis of contacts of an index case suspected of harbour-( 9 3 ) ing i s o n i a z i d - r e s i s t a n t mycobacteria, Farer suggested : 1 ) Rifampin - questions as to i t s safety as a prophylactic remain unanswered. 2 ) Isoniazid - given i n the hope of a preventive e f f e c t . 6 1 3 ) Close scrutiny of the contacts for a period of several years and aggressive treatment on f i r s t suspicion of active disease. 5 . 1 8 Non-Compliance Becker and Maiman^^ reported that the percentage of pa-t i e n t s f a i l i n g to take medications recommended by t h e i r physicians ranged between 2 0 % and 8 2 % . The same authors stated that between 2 5 and 5 0 % of patients taking t h e i r medications make errors i n the actual administration of drugs prescribed. An exhaustive review of the l i t e r a t u r e ( 9 5 ) by Davis suggested that 3 0 to 3 5 7 o of patients f a i l to follow t h e i r physicians' recommendations. Moulding, Onstand, and S h a r b a r o ^ ^ demonstrated that 3 1 % of patients who had been prejudged as r e l i a b l e by t h e i r physicans had taken less than 7 0 % of t h e i r i s o n i a z i d . Urine samples taken during surprise home v i s i t s demonstrate even higher rates of non-compliance. Compliance decreases as the dur-ation of therapy increases, as the therapeutic regimen becomes more complicated, and as the dosage becomes more . (97) frequent. In essence, the greater the human behavioural change required by the regimen, the lower w i l l be the com-i - A u -u - ( 9 8 , 9 9 , 1 0 0 , 1 0 1 ) pliance and co-operation by the patient. ' ' ' Side e f f e c t s of treatment were given as reasons f o r non-compliance only 5 to 1 0 % of the time. 62 Grzybowski, Galbraith and D o r k e n 1 1 U J ; achieved 90% compliance i n a chemoprophylactic t r i a l among Canadian Eskimos over a period of 18 months. Subsequent follow-up over 3 years showed 100% protection amongst the treatment group whereas the control group of 217 indiv i d u a l s developed active tuber-c u l o s i s at a rate of 1.8 per 1,000. The 907» compliance was achieved by using native Eskimo health workers who administered the ethambutol and i s o n i a z i d o r a l l y on an intermittent basis three times per week. Compliance of 50% - 70% can be expected f o r a chemoprophylactic program aimed at reducing the incidence rate of Pulmonary Tubercul-osis among the refugee immigrants. 5.19 Summary In B r i t i s h Columbia, control measures are dir e c t e d by the D i v i s i o n of Tuberculosis Control. Health c l i n i c s run by t h i s D i v i s i o n provide a r e f e r r a l service for the general physicians and an ambulatory treatment service for patients. H o s p i t a l i z a t i o n i s mostly confined to patients who are highly infectious source cases with sputum smears p o s i t i v e for M. tuberculosis. Mass screening i s confined to se l e c t h i g h - r i s k groups. Follow-up of contacts of i n f e c t i o u s index cases has proved e f f e c t i v e i n r e s t r i c t i n g the spread of tuberculosis. Physicians would be more e f f e c t i v e i n preventing the spread of the disease i f they were taught to "Think Tuberculosis." Potential public health hazards from Pulmonary Tuberculosis among long-stay v i s i t o r s and 63 students from c e r t a i n areas of Asia would be prevented by medical screening s i m i l a r to the pre-immigration screen-ing applied to immigrants. BCG o f f e r s s i g n i f i c a n t protec-t i o n to hi g h - r i s k groups. Chemoprophylaxis with i s o n i a z i d i s beset with problems of non-compliance, r e s i s t a n t myco-bacte r i a , and adverse reactions; nevertheless, i t i s effect-ive i n decreasing the incidence of Pulmonary Tuberculosis i n s e l e c t groups. 64 6. Methods 6.1 Introduction An assessment of the public health significance of Pulmon-ary Tuberculosis could consider d i s e a s e - s p e c i f i c rates of mortality 1 , m o r b i d i t y , 1 1 or h o s p i t a l i z a t i o n . 1 1 1 6.2 Rationale for Comparing Morbidity Rates Pulmonary Tuberculosis has a d e f i n i t e mortality rate. 6.2.1 Mortality rate: Over the past 30 years, mortality rates have declined and, i n 1980, are not considered a sen s i t i v e i n d i c a t o r of the incidence of Pulmonary Tuberculosis. 6.2.2 Morbidity rates: The age-specific incidence rate of Pulmonary Tuberculosis i s reported each year f o r several population groups by the D i v i s i o n of Tuberculosis Control. The s t a t i s t i c s quoted are of cases diagnosed by a combin-ation of c l i n i c a l presentation, physical examination and confirmation by skin t e s t i n g , chest x-ray, and sputum c u l -ture. The culture of M. tuberculosis i s the f i n a l confirm-ation of the diagnosis of tuberculosis. Comparison of the morbidity rates of Pulmonary Tuberculosis among the various population groups w i l l demonstrate the public health s i g n i f i c a n c e of Pulmonary Tuberculosis among the Southeast Asian refugee immigrants. Footnotes ( i ) , ( i i ) , ( i i i ) Disease-specific rates of mortal-i t y , morbidity, h o s p i t a l i z a t i o n defined on pages l l and 12. 65 6.2.3 H o s p i t a l i z a t i o n Rates Anti-tuberculosis chemotherapy has removed the necessity of hospital treatment for most cases of Pulmonary Tubercul-o s i s . The h o s p i t a l i z a t i o n rate i s not a good i n d i c a t o r of the public health significance of this disease. 6.3 Population Groups to be Compared The rate of acute Pulmonary Tuberculosis among: 1) the refugee immigrants a r r i v i n g i n B r i t i s h Columbia i n 1979 - 1980 was compared with the rates of acute Pulmonary Tubercul-osis for the three-year period 1976 - 1978 among 2) the general population of B r i t i s h Columbia, 3) the non-refugee Asian immigrants, and 4) registered native Indians i n B r i t i s h Columbia. S t a t i s t i c s were extracted from the D i v i s i o n of Tuberculosis Control of B r i t i s h Columbia and the Federal Department of Health and Welfare Canada to enable c a l c u l a t i o n of the age-specific incidences and prevalences of Pulmonary Tuber-c u l o s i s . 6.3.1 Age-Specific Incidence of Pulmonary Tuberculosis  for the General Population i n B r i t i s h Columbia The annual reports of the Di v i s i o n of Tuberculosis Control did not specify age-specific rates of Pulmonary Tuberculosis 66 which were calculated i n the following manner: Incidence of a l l active cases ( 0 - 1 4 yrs.) Number of cases of Pulmonary Tuberculosis for age bracket (0 - 14 yrs.) Number of a l l cases of active tuberculosis (pulmonary and extra-pulmonary) 1978 incidence rate of Pulmonary Tuberculosis for age bracket (0 - 14 yrs.) i s X 6.6 = 6.3.2 Age-specific Incidence of Pulmonary Tuberculosis  for Non-Refugee Asian Immigrants to B r i t i s h Columbia f o r 1976, 1977, and 1978 The number of non-refugee Asian immigrants demonstrating acute Pulmonary Tuberculosis within one year of a r r i v a l i n B r i t i s h Columbia was obtained from the records of the D i v i s i o n of Tuberculosis Control. From the Department of Immigration i n B r i t i s h Columbia, the t o t a l numbers of Asian immigrants a r r i v i n g i n B r i t i s h Columbia f o r 1976, 1977, and 1978 were obtained. The number of Asian immigrants a r r i v i n g i n each age bracket was calculated so: 1) - Asian immigrants as a percentage of the t o t a l number of immigrants to B r i t i s h Columbia was c a l c u l a t e d . 2) Applying the percentage of Asian immigrants to the t o t a l number of immigrants i n each age bracket gave Footnotes: ( i ) Table 18A, Page 17, Annual Report 1 9 7 8 . ( 1 0 4 ) ( i i ) Table 23, Page 25, Annual Report 1978. ( i i i ) Table 23, Page 25, Annual Report 1978. (iv) Quoted i n Table 6, Page 76. 6.6 ( i ) 3 6 . 0 ( i i ) 3 9 . 0 ( i i i ) 6 . 1 ( i v ) 67 the number of Asian immigrants i n each age bracket for 1976, 1977, and 1978. (Appendix 3, Tables A8 -A13) (Pages 114 - 119) Age-specific incidence of Pulmonary Tuberculosis among non-refugee Asian immigrants for each year: Number of cases i n each age bracket 1976-1978 population i n each bracket Where the records of the D i v i s i o n of Tuberculosis Control did not specify the actual date of a r r i v a l of an Asian immigrant, (e.g. year of a r r i v a l s p e c i f i e d but not the month), i t was assumed that cases of Pulmonary Tubercul-osis i d e n t i f i e d up to and including A p r i l 30 of the year following a r r i v a l occurred within one year of actual a r r i v a l . Since 1976, a number of Asian immigrants with pre-existing Pulmonary Tuberculosis have been admitted to B r i t i s h Columbia. P r o v i n c i a l l e g i s l a t i o n allows admission of immigrants with active Pulmonary Tuberculosis on compassionate grounds.^ u^^ These cases were included i n s t a t i s t i c s quoted i n the annual reports of the D i v i s i o n of Tuberculosis. To prevent i n f l a t -ing the incidence rate of Pulmonary Tuberculosis among non-refugee Asian immigrants, individuals admitted to B r i t i s h Columbia with pre-exising active Pulmonary Tuberculosis were excluded from the c a l c u l a t i o n of rates among the non-refugee Asian immigrants. 68 6 . 3 . 3 Age-specific Rate of Pulmonary Tuberculosis Among  Registered Native Indians i n B r i t i s h Columbia for 1 9 7 6 ,  1 9 7 7 , and 1 9 7 8 The number of cases of Pulmonary Tuberculosis for each age bracket ( 0 - 1 4 , 1 5 - 2 4 yrs. etc.) was obtained from the records of the D i v i s i o n of Tuberculosis Control. The population of r e g i s t e r e d native Indians for each age bracket was obtained from the Department of Indian A f f a i r s . Age-s p e c i f i c rates of Pulmonary Tuberculosis were calculated as follows: Number of cases of Pulmonary Tuberculosis fo r each age bracket f o r each year  Population of each age bracket for each year In a personal communication, Dr. C. Laberge^^*^ indicated that 3 6 % of a l l cases of Pulmonary Tuberculosis were d i s -covered by the screening program conducted by the Federal Health and Welfare, Indian A f f a i r s Department. Assuming that the r e g i s t e r e d native Indians not screened were homogenous with those that were screened, the preval-ence of Pulmonary Tuberculosis among the native Indians ( i f 1 0 0 7 o were screened) would be: - ', i n n ( i ) o A ( i i ) ( i i i ) i c r • V 100 Y 36 v -a CR 36 Y H l ( i v ) Where: A i s the percentage of native Indians screened each year; f o r 1 9 7 6 , A = 2 7 . 7 % Footnotes: ( i ) Table 5 , Page 6 9 . . ( i i ) The percentage of ALL cases of Pulmonary Tuberculosis that was diagnosed by the screening program, ( i i i ) Table A14, Appendix 4, Page 120. (iv) The number of cases of Pulmonary Tuberculosis presenting c l i n i c a l l y each year, and therefore not i d e n t i f i e d by the screening program. 6 9 TABLE 5 Registered Indians screened f o r years 1976-78 Registered Indian p o p u l a t i o n f o r B.C. (1976) 53,342 A v a i l a b l e p o p u l a t i o n f o r screening 49.6% 26,506 To t a l screened on reserves 16,153 N . I . S . ^ screened on rese r v e s 1,369 14,784 1976 r e g i s t e r e d Indian p o p u l a t i o n (53,342) screened 27.7% 1977 r e g i s t e r e d Indian p o p u l a t i o n (54,753) screened 23.9% 1978 r e g i s t e r e d Indian p o p u l a t i o n (55,217) screened 18.5% Source: Dr. C. Laberge Indian Health Branch Willow Chest C l i n i c Vancouver, B.C. Footnote ( i ) N.I.S. - Non Indian Status 70 1 9 7 7 , A = 2 3 . 9 7 o ( i ) 1 9 7 8 , A = 1 8 . 5 7 0 B i s the number of ALL cases of Pulmonary Tuber-c u l o s i s diagnosed among native Indians each year, by screen-ing AND c l i n i c a l presentations for 1 9 7 6 , B = 5 9 1 9 7 7 , B = 4 7 ( i i i ) 1 9 7 8 , B = 8 4 6 . 4 Incidence Versus Prevalence Comparisons between incidence rates and prevalence rates are not s t a t i s t i c a l l y v a l i d . The refugee immigrants were rescreened aft e r a r r i v a l i n B r i t i s h Columbia. The rate of Pulmonary Tuberculosis iden^ t i f i e d amongst the refugee immigrants resembles, a preval-ence rate rather than an incidence rate. The general pop-u l a t i o n and non-refugee Asian immigrants are not screened i n B r i t i s h Columbia; the rates of Pulmonary Tuberculosis among these groups are incidences. To compare s i m i l a r rates, the maximum possible prevalence rates f o r the general population and non-refugee Asian immigrants were estimated with the following l i m i t a t i o n s and assumptions: 1 ) No account was taken of spontaneous remission. In the general population and non-refugee•Asian immigrants, Footnotes: ( i ) & ( i i i ) see previous page (Page 6 8 ) . 71 c l i n i c a l diagnosis was by presentation of symptoms and/or signs — not by screening procedures. 2) It was assumed that undiagnosed active Pulmonary Tuber-culo s i s present on a p a r t i c u l a r date would progress to c l i n i c a l symptoms and/or signs, r e s u l t i n g i n a diag-nosis of Pulmonary Tuberculosis within three years providing spontaneous remission did not occur. (See Assumption 1) 3) A l l cases of Pulmonary Tuberculosis occurring i n each cohort of the general population, or each cohort of non-refugee Asian immigrants, within three years were due to the prevalence of active disease i n the cohort at the commencement of the three-year period. Some cases would be endogenous re a c t i v a t i o n , others new in f e c t i o n s ; for the estimation of maximum possible prevalence, i t was assumed that a l l cases were due to the prevalence of disease at the commencement of the three-year period. 4) The refugee immigrants were rescreened and, according to G r z y b o w s k i v ' and Chao, 80% of primary active cases and 50%, of minimally active cases would remit spontaneously. Allowance i s made for possible spontan-eous remission amongst the refugee immigrants; cases have not been diagnosed because of c l i n i c a l symptoms or signs, but were i d e n t i f i e d by the rescreening process. Within the l i m i t a t i o n s and assumptions made i n 1 - 4 above, 72 estimates of the maximum possible prevalences among the general population and the non-refugee Asian immigrants were made for 1976, 1977, and 1978 and compared with the prevalence (allowing f o r possible spontaneous remission) among the refugee immigrants. 6.5 Prevalence of Bacteriologically-Confirmed Pulmonary Tuber-c u l o s i s (109) Dr. S. Grzybowski, i n a personal communication, stated that only prevalence rates involving confirmation of M. tuberculosis by culture were suitable for comparison. The c a l c u l a t i o n i s : -the number of cases demonstrating M. tuberculosis by culture population of group i n which cases i d e n t i f i e d 6.6 Culture-Positive Cases of Pulmonary Tuberculosis 1) Among the General Population The number of cases of Pulmonary Tuberculosis confirmed bacteriologically was obtained from the annual reports of the D i v i s i o n of Tuberculosis Control f o r the years 1976, 1977, and 1978. The estimated population figures used by the D i v i s i o n of Tuberculosis Control were u t i l -ized i n c a l c u l a t i n g the prevalence rates of culture-p o s i t i v e cases for 1976, 1977, and 1978. 2) Among Non-Refugee Asian Immigrants The number of c u l t u r e - p o s i t i v e cases occurring for the years 1976, 1977, and 1978 was extracted from the records of the D i v i s i o n of Tuberculosis Control. The 73 number of Asian immigrants giving B r i t i s h Columbia as t h e i r destination was obtained from the Department of Immigration for the years 1976, 1977, and 1978, and used as the denominator i n c a l c u l a t i n g the prev-alence rate of cu l t u r e - p o s i t i v e cases of Pulmonary Tuberculosis among non-refugee Asian immigrants. There were few cu l t u r e - p o s i t i v e cases occurring each year among non-refugee Asian immigrants. No attempt was made to correct for possible errors i n the denominator caused by new Asian immigrants a r r i v i n g i n B r i t i s h Columbia from other provinces, or departing from B r i t i s h Columbia to other provinces within t h e i r f i r s t twelve months i n Canada. The ove r a l l effect on the prevalence rates would be small. 3) Among Registered Native Indians The number of cases of Pulmonary Tuberculosis confirmed b a c t e r i o l o g i c a l l y was obtained from the annual reports of the D i v i s i o n of Tuberculosis Control f o r the years 1976, 1977, and 1978. Allowances were made for the percentages a c t u a l l y screened each year. The estimated registered native Indian population figures for 1976, 1977, and 1978 used by the D i v i s i o n of Tuberculosis Control were u t i l i z e d as the denominator i n c a l c u l a t -ing the prevalence rates of cu l t u r e - p o s i t i v e cases for each year. 4) Among the Refugee Immigrants The number of cases of Pulmonary Tuberculosis diagnosed 74 i n B r i t i s h Columbia and confirmed b a c t e r i o l o g i c a l l y was obtained from the records of the refugee immigrants kept by the D i v i s i o n of Tuberculosis Control. Records of cases of tuberculosis were kept c e n t r a l l y at the D i v i s i o n of Tuberculosis Control i n Vancouver even though diagnosis and treatment could take place away from Vancouver. The number of refugee immigrants who had been screened by May, 1980, was used as the denominator i n c a l c u l a t i n g the rate of Pulmonary Tuberculosis con-firmed b a c t e r i o l o g i c a l l y . \ 7 5 Results  General The incidence of a l l forms of tuberculosis i n the general population declined 8 . 3 7 o per year from 1 9 7 0 to 1 9 7 4 . (See Table 1 , Page 1 8 ) . The 1 9 7 6 incidence rate was 1 3 . 7 per 1 0 0 , 0 0 0 (Table 1 , Page 1 8 ) . Large variations are noted i n the incidence rates of d i f f e r e n t segments of the popul-ation. To e s t a b l i s h the point prevalence of Pulmonary Tuber-c u l o s i s i n the general population would require a large public survey involving: ( 1 ) Mantoux t e s t i n g , ( 2 ) a chest x-ray, and ( 3 ) sputum cultu r e s . A de c l i n i n g incidence rate of 1 2 . 7 / 1 0 0 , 0 0 0 would not j u s t i f y the cost of such a survey. 7 . 2 Rates of Pulmonary Tuberculosis Among the General Population  and Non-Refugee Asian Immigrants Direct comparison of the rates as i n Table 6 (Page 7 6 ) shows the refugee immigrants with an ov e r a l l rate of 4 8 0 : 1 0 0 , 0 0 0 , while the general population has an average o v e r a l l rate of 1 2 . 8 : 1 0 0 , 0 0 0 f o r the years 1 9 7 6 , 1 9 7 7 , and 1 9 7 8 . 7 . 3 Estimate of the Maximum Possible Prevalence of Pulmonary  Tuberculosis Among the General Population Within the l i m i t a t i o n s and assumptions set out i n Methods, Section 6 . 4 (Page 7 0 ) , the maximum possible prevalence of Pulmonary Tuberculosis among the general population i n 1 9 7 6 was: 7 . 7 . 1 TABLE 6 Comparison of Rate of Pulmonary T u b e r c u l o s i s Amongst Refugee Immigrants and General Population i n B.C. Rates per 100,000 Age Bracket Rate Amongst Refugees^ 1' 1 ^  A g e - S p e c i f i c Incidence Amongst,.* General Population i n B.C. ^' 1976 1977 1978 0 - 1 4 574 4.2 2.5 6.1 15 - 24 205 7.9 5.0 9.2 25 - 44 700 12.8 13.8 12.0 45 - 64 Not S i g n i f i c a n t 19.3 18.4 18.9 65 + 31.1 28.6 34.5 Ov e r a l l 480 12.8 11.7 13.8 See Appendix I (Page 105)/]] See Appendix 2 (page 1 0 9 ) U T 77 Cases of Pulmonary Tuberculosis diagnosed i n : -1976 314 1977 292 1978 344 Total over 3 years F5U General Population 1976 . 2,453,125 .*. Maximum possible prevalence i n 1976 was 950 = 38 / 100,000 7.4 Estimate of the Maximum Possible Prevalence of Pulmonary Tub-er c u l o s i s Among Non-Refugee Asian Immigrants Within the l i m i t a t i o n s and assumptions set out i n Methods, Section 6.4 (Page 70), the maximum possible prevalence of Pulmonary Tuberculosis among the non-refugee Asian immigrants f o r 1976 was:-Cases of Pulmonary Tuberculosis diagnosed i n B. C. i n : -1976 3 1977 . 8 ( i ) 1978 4 Total over 3 years f5 Population of non-refugee Asian immigrants to B. C. f o r 1976 8,808 Maximum possible prevalence i n 1976 was 15 8,808 =170 / 100,000 Footnote ( i ) Table A12, Appendix 3 (Page 118) 7 8 . 5 Rate o f Pulmonary T u b e r c u l o s i s Among Refugee Immigrants Ad-j u s t e d f o r Spontaneous R e m i s s i o n As d i s c u s s e d on Page 7 1 , spontaneous r e m i s s i o n would o c c u r among c a s e s o f Pulmonary T u b e r c u l o s i s i d e n t i f i e d by a s c r e e n -i n g program as p r o v i d e d f o r t h e r e f u g e e i m m i g r a n t s . A l l o w -/ • \ i n g f o r spontaneous r e m i s s i o n o f 8 0 7 , 1 o f p r i m a r y a c t i v e / • • \ c a s e s and 5 0 7 o o f m i n i m a l l y a c t i v e c a s e s , t h e a d j u s t e d r a t e o f Pulmonary T u b e r c u l o s i s among t h e r e f u g e e i m m i g r a n t s would be 2 1 7 / 1 0 0 , 0 0 0 ( 1 1 1 } . 6 A d j u s t e d R a tes o f Pulmonary T u b e r c u l o s i s Among R e g i s t e r e d  N a t i v e I n d i a n s i n B r i t i s h Columbia R e g i s t e r e d n a t i v e I n d i a n s a r e s c r e e n e d by the Department o f H e a l t h and W e l f a r e Canada - I n d i a n A f f a i r s . T a b l e 5 (Page 6 9 ) i s an i n d i c a t i o n o f t h e s c r e e n i n g performed. T a b l e 7 (Page 7 9 ) i s a d i r e c t c o m p a r i s o n o f the r a t e s o f Pulmonary T u b e r c u l o s i s among t h e r e f u g e e i m m i g r a n t s f o r 1 9 7 9 / 8 0 and the r e g i s t e r e d n a t i v e I n d i a n p o p u l a t i o n f o r 1 9 7 6 , 1 9 7 7 , and 1 9 7 8 . From T a b l e 5 (Page 6 9 ) , p e r c e n t a g e s o f a v a i l a b l e p o p u l a t i o n s c r e e n e d i n each y e a r were: F o o t n o t e s : ( i ) ( i i ) ( i i i ) D i s c u s s e d Page 7 1 D i s c u s s e d Page 7 1 T a b l e A3, Appendix 1 , page 1 0 6 . TABLE 7 A g e - s p e c i f i c Rate of Pulmonary T u b e r c u l o s i s Amongst Refugee Immigrants Contrasted with A g e - s p e c i f i c Incidence Amongst Native Indians - 1976, 1977, 1978 Age Bracket A g e - s p e c i f i c Rate Amongst Refugees A g e - s p e c i f i c Incidence Amongst ' Native Indians 1976 1977 1978 0 - 14 574 29.3 9.5 71.1 15 - 24 " 205 67.2 7.4 115.5 25 - 44 700 157.5 193.7 182.6 45 - 64 mm 241.8 270.0 305.1 65+ f i g u r e s too small f o r s i g n i f i c a n c e 624.0 236.3 690.7 480 110.6 85.8 152.1 See Appendix 4 Table A14 (page 120) 80 Year Percentage Screened Available Population 1976 27.7 53,342 1977 23.9 54,753 1978 18.5 55,217 As discussed on Page 68, 367, of cases of Pulmonary Tubercul-osis were i d e n t i f i e d by screening techniques. I f 1007, of a v a i l a b l e population had been screened, t o t a l a c t i v e Pulmon-ary Tuberculosis would be:-1 9 7 6 X ^ X 5 9 ( 1 ) + [59 - X 59)] - 115 1 9 7 7 - ( l ^ X 4 7 , ] / l O ! 1 " 8 ^ x ^ x 8 4 ( D + [ 8 4 . ' ( T 3 « X 8 4 ) ] . 2 1 7 Prevalences of Pulmonary Tuberculosis for the years 1976, 1977, and 1978, assuming 1007, of screening, would be: 1976 I Per 100,000 t o t a l expected cases 115 _ o-i c population of registered native Indians 53,342 1977 „ 101 • , 37T7371 = 1 « 4 1978 " . 2 1 7 55,217 " 3 9 2 The rate of Pulmonary Tuberculosis among the refugee immig-rants and the registered native Indians i n B r i t i s h Columbia (adjusted for screening of 1007, of the available population) are d i r e c t l y comparable. Prevalence i s compared with preval-ence . Footnote: (i) Total cases of Pulmonary Tuberculosis among registered native Indians from annual reports, D i v i s i o n of Tuberculosis Control 1976/'77/* 78. 81 7.7 Cases of Pulmonary Tuberculosis Confirmed B a c t e r i o l o g i c a l l y According to G r z y b o w s k i , ^ ^ comparisons of tuberculosis prevalence rates are only v a l i d i f the rates compared are those of cases of tuberculosis confirmed b a c t e r i o l o g i c a l l y . The presence of M. tuberculosis on culture i s i r r e f u t a b l e evidence of disease. Tuberculosis skin tests and chest x-rays are subject to in t e r p r e t i v e error. 7.7.1 Rate of Pulmonary Tuberculosis Confirmed Bacteriolog-i c a l l y Among General Population According to the method outlined i n Methods, Section 6.6 (Page 72), the rates for 1976, 1977, and 1978 among the gen-e r a l population were: 1976 1977 1978 / • \ Cases confirmed b a c t e r i o l o g i c a l l y 243 241 278 Estimated population (in m i l l i o n s ) ( 1 1 J 2.461 2.486 2.5 Rate per 100,000 9.9 9.7 11.2 Average f o r 3 years = ^ ^ 8 - = 10.3/100,000 7.8 Cases of Pulmonary Tuberculosis Confirmed B a c t e r i o l o g i c a l l y  Among Non-Refugee Asian Immigrants f o r 1976, 1977, and 1978 (see following page) Footnotes: ( i ) From Annual Reports 1976, 1977, 1978 - Div-i s i o n Tuberculosis Control ( i i ) Calculated from Annual Reports 1976, 1977 D i v i s i o n Tuberculosis Control 82 1976 1977 1978 (i ) Cases confirmed b a c t e r i o l o g i c a l l y 1 8 3 Non-refugee Asian immigrants a r r i v i n g each y e a r ( l l ) 8,808 6,464 5,301 Rate per 100,000 11 124 57 Average f o r 3 years = 192 = 64/100,000 7.9 Cases of Pulmonary Tuberculosis Confirmed B a c t e r i o l o g i c a l l y  Among Registered Native Indians Cases confirmed b a c t e r i o l o g i c a l l y 1 1 1976 1977 1978 51 42 51 Adjusting for 1007, screening of registered Indians population See Methods, Section 6.3.3 (Page'69) 1976 ( ^ X ^ X 51) + ( 5 1 - ^ X 5 1 ) = 99 1 9 7 7 (TuTJ X 7379 X 4 2 ) + ( 4 2 T u T J X 4 2 ) = 1 0 0 1 9 7 8 ( T o £ X T ^ X 5 1 > + ( 5 1 - ^ X . S l ) = 132 Prevalence rates of Pulmonary Tuberculosis proven by culture among the registered native Indians of B r i t i s h Columbia (per 100,000) 1976 - cu l t u r e - p o s i t i v e cases 1 1 , . . _ 99 _ 1 o c native Indian population 1 9 7 6 l i v ; " 53,342 " 1 0 3 1977 - cu l t u r e - p o s i t i v e cases _ 100 native Indian population 1977 ~ 54,753 1978 - cu l t u r e - p o s i t i v e cases _ 132 _ native Indian population 1978 55,217 182 239 Footnotes: ( i ) From Records of D i v i s i o n of Tuberculosis Control ( i i ) Table A10, Appendix 3 (Page 116) ( i i i ) Annual Reports, D/T.B. Control, 1976 - 1978. (iv) Table 5, (Page 69) 83 7.10 Cases of Pulmonary Tuberculosis Confirmed B a c t e r i o l o g i c a l l y  Among the Refugee Immigrants From Table 8, Page 84, only 2 cases of Pulmonary Tuberculosis were confirmed by culture of M. tuberculosis among the 3,125 refugee immigrants screened up to May, 1980. Rate of cases confirmed b a c t e r i o l o g i c a l l y per 100,000: = 3 — = 64/100,000. 7.11 Summary To e s t a b l i s h the prevalence of Pulmonary Tuberculosis among the general population would require a large public survey; t h i s would not be j u s t i f i e d by 1980 incidence rates. The rates of Pulmonary Tuberculosis, using maximum possible es-timated prevalence rates f o r the general population and non-refugee Asian immigrants, were compared with the prevalence rate (adjusted f o r probable spontaneous remission) among the refugee immigrants. A comparison with the prevalence among registered native Indians, a f t e r adjustment for 1007o screen-ing, was also made. Rates of cases of Pulmonary Tuberculosis confirmed b a c t e r i o l o g i c a l l y occurring among the four population groups were compared. 84 TABLE 8 Age, Sex, T u b e r c u l i n Response, R a d i o l o g i c a l Diagnosis o f Refugee Immigrants Diagnosed as Pulmonary T u b e r c u l o s i s May, 1980 from 3125 Rescreened i n B. C. Case No. Sex Year o f B i r t h T u b e r c u l i n Test R a d i o l o g i c a l Diagnosis 251 475 M 1973 25 mm Primary A c t i v e 251 812 M 1977 20 mm Suspect Primary A c t i y e 252 008 F 1958 20 mm Suspect Minimal A c t i v e 252 180 F 1952 40 mm Minimal A c t i v e ( P o s i t i v e Sputum) 252 214 F 1976 20 mm Primary A c t i v e 252 321 F 1941 17 mm Minimal A c t i v e 252 450 M 1948 42 mm Minimal A c t i v e 252 527 M 1961 20 mm Primary A c t i v e 252 562 F 1976 17 mm Primary A c t i v e 252 584 F 1942 14 mm Moderate A c t i v e 252 619 M 1941 18 mm Far Advanced ( P o s i t i v e Sputum) 252 720 M 1936 10 mm Minimal A c t i v e 252 931 M 1911 Negative Minimal A c t i v e 253 569 F 1977 14 mm Primary A c t i v e 253 589 M 1968 16 mm Minimal A c t i v e Age Bracket Numbers Sex Rates 0 - 1 4 6 M F 15 - 24 2 8 7 2 5 - 4 4 6 4 5 - 6 4 65+ 1 85 Discussion What influence w i l l Pulmonary Tuberculosis among the refugee immigrants have upon the public health of the population of B r i t i s h Columbia? The f i r s t paragraph of the introductory chapter quotes two opposing viewpoints: (111) 1) Dr. S. Grzybowski, while acknowledging the greater burden of disease among Asian immigrants, d i d not consider to public health hazards s u f f i c i e n t to support re-screening of Asian immigrants. (112) 2) Dr. A. Larsen, r a i s e d the p o s s i b i l i t y of spread of Pulmonary Tuberculosis from Asian refugee immigrants to the general public and recommended the re-screening program. Comparisons from a screened group to a non-screened group have to overcome the difference between prevalence rate and incidence rate. Estimations of prevalence for Pulmonary Tuberculosis c l a s s i f i e d r a d i o l o g i c a l l y were made for the general population and the non-refugee Asian immigrants to f a c i l i t a t e d i r e c t comparisons with the rate of Pulmonary Tuberculosis among the refugee immigrants. Registered native Indians undergo screening f o r tuberculosis by the Indian Health D i v i s i o n of the Federal Department of Health and Wel-fare Canada. Estimates of the prevalence of disease were made for the registered native Indian population assuming the segment of the population not screened was homogeneous with the segment of the population that was screened. The 86 prevalence rate of Pulmonary Tuberculosis among the registered Indian population might be higher than estimated because of avoidance of screening by some native Indians. has stated that cases of Pulmonary Tuberculosis confirmed by culture of M. tuberculosis cannot be disputed. Prevalence rates of bacteriologically-proven cases were also compared. The general prevalence among the refugee immigrants was 480/ 100,000. The maximum possible prevalence among the general population for 1976 was 38/100,000. Allowing for possible spontaneous remission among the refugee immigrants, the ad-justed rate becomes 217 : 100,000. General Population 38 : 100,000 Refugee Immigrants 217 : 100,000 The refugee immigrants demonstrate about s i x times the rate of Pulmonary Tuberculosis that occurs i n the general popul-ation. 8.2 Comparison of Prevalence Rates of Cases Confirmed B a c t e r i o l -Interpretation of chest x-rays i s subjective. (113) Grzybowski 8.1 Comparison of Rates of Pulmonary Tuberculosis Among 1) the Refugee Immigrants and 2) the General Population o g i c a l l y Among refugee immigrants (Page 83) 64 : 100,000 87 Among general population (Page 82) For the years 1976, 1977, and 1978 average 10.3 : 100,000 The refugee immigrants demonstrate about six times the rate of cases of Pulmonary Tuberculosis confirmed b a c t e r i o l o g i c a l l y than occurred i n the general population. Based on these rates, the refugee immigrants present a s i g n i f -icant public health hazard for Pulmonary Tuberculosis to the general population of B r i t i s h Columbia. 8.3 Comparison of the Rates of Pulmonary Tuberculosis Among Non- Refugee Immigrants The refugees are coming to Canada from the same general area as immigrants from Asia. Do the refugee immigrants constitute a greater public health hazard than non-refugee Asian immig-rants? As Grzybowski stated (Page 1), " I t i s debatable whether any sensible and e f f e c t i v e tuberculosis control program could or should be i n s t i t u t e d i n thi s group." The estimated maximum possible prevalence i n the cohort of • non-refugee Asian immigrants for 1976 was calculated as 170/ 100,000 (Page 77). The prevalence of Pulmonary Tuberculosis among the refugee immigrants for 1979/80, adjusted for possible spontaneous remission, was 217 / 100,000 (Page 78), i . e . 1.25 times the 88 estimated maximum possible prevalence among the non-refugee Asian immigrants for 1976. According to Grzybowski (Page 72 ), the only v a l i d method of comparing prevalences i s to compare the rates of cases con-firmed by culture of M. tuberculosis; the comparisons would be: Refugee Immigrants Non-Refugee Asian Immigrants 1979/80 1976 1977 1978 6 4 ( i ) 11 124 5 7 ( i i ) A 192 Average = ~J~ = 64 : 100,000 From t h i s perspective, the public health r i s k f o r Pulmonary Tuberculosis i s s i m i l a r f o r the refugee immigrants and the non-refugee Asian immigrants. Both are about s i x times the rate of the general population. 8.4 Comparison of the Rates of Pulmonary Tuberculosis Between  the Refugee Immigrants and Registered Native Indians i n  B r i t i s h Columbia • According to Grzybowski, ^  "The tuberculosis problem i s very unevenly d i s t r i b u t e d among Canadains. Certain groups show very high rates of disease. The rates among Canadian Indians are consistently some ten times higher than among other Canadians; what i s even more worrying i s that, i n recent Footnotes: ( i ) Results 7.10 (Page 83) ( i i ) Results 7.8 (Page 82) 89 years, these rates have shown no i n d i c a t i o n of a d e c l i n e . " Pulmonary Tuberculosis among registered native Indians i s a public concern. Native Indians are one segment of the Canadian population screened extensively. From Page 80, the rates of Pulmonary Tuberculosis among nat-ive Indians, assuming 100% of the population was screened, were: Rate Per 100,000 1976 1977 1978 215 184 392 The prevalence rate for Pulmonary Tuberculosis among refugee immigrants was 480 : 100,000, i . e . 1.2 - 2.2 times as frequent as the rate occurring among the native Indians. 8.5 Comparison of the Rate of Cases ofPulmonary Tuberculosis Confirmed by Culture of M. tuberculosis Rates Per 100,000 Refugee Immigrants Native Indians 1979/80 1976 1977 1978 64 ' 185 182 239 1 2.9 2.8 3.7 (Average) 3 .1 Pulmonary Tuberculosis with sputum containing M. tuberculosis i s a s i g n i f i c a n t public health hazard. It occurs three times more frequently among native Indians than among refugee immig-rants . 90 8.6 Early Radiological Diagnosis of Pulmonary Tuberculosis Table 9 (Page 91), Table 10 (Page 92), and Table 11 (Page 93) display the percentages of chest x-ray of cases of Pul-monary Tuberculosis i n each of five c l a s s i f i c a t i o n s of r a d i o l -o g i c a l diagnosis for the refugee immigrants, the general population, the general Asian immigrants, and the registered native Indians. Most cases of Pulmonary Tuberculosis among the refugee immig-rants have been diagnosed at an e a r l i e r stage i n the disease process than cases among the general population, Asian immig-rants, and native Indians. Refugee immigrants are a pre-selected group. Cases of active tuberculosis have been iden-t i f i e d and treated before the group arri v e d i n Canada. Why i s there a prevalence of Pulmonary Tuberculosis of 480/100,000 among the refugee immigrants on a r r i v a l i n Canada? Dr. Larsen, p r o v i n c i a l epidemiologist, stated, "the medical examinations c a r r i e d out by Federal Government overseas have f a i l e d to detect a l l of the serious chronic communicable diseases i n the Indo-Chinese refugees ." ^ .-^ ^ ^  8.7 Federal Immigration Screening Policy Prospective immigrants eleven years of age or younger are not ro u t i n e l y screened for Pulmonary Tuberculosis. Table 8 (Page 84) gives the birthdate of the in d i v i d u a l s with Pul-monary Tuberculosis diagnosed aft e r a r r i v a l i n B r i t i s h Columbia; s i x of these i n d i v i d u a l s were eleven years or younger when TABLE 9 Percentage of R a d i o l o g i c a l Diagnoses i n Various C l a s s i f i c a t i o n s f o r Refugee Immigrants and General Population 1976 - 1978 R a d i o l o g i c a l Diagnosis Refugee Immigrants % 1976 % 1977 % 1978 % Primary Minimal 87 52 48 53 Moderately Advanced 7 21 28 23 Far Advanced 6 13 14 14 Other - 14 10 10 100 100 100 100 See Appendix 1, Table A2 (page 107) 92 TABLE 10 R a d i o l o g i c a l Diagnosis o f Pulmonary T u b e r c u l o s i s amongst the Refugee immigrants and general Asian immigrants 1976-78. R a d i o l o g i c a l Diagnosis Refugee Immigrants 1976 1977 1978 Primary Minimal Moderate Far Advanced (From Table 8) No. % 6 87 No. % No. % No. % 3 -37 87 50 1 4 2 63 1 25 1 25 Other 15 100 13 3 100 8 100 4 100 Information e x t r a c t e d from Willow Chest C l i n i c Records. Table 10 excludes cases of t u b e r c u l o s i s admitted under s p e c i a l m i n i s t e r ' s permit or with a d i a g n o s i s of t u b e r c u l o s i s e s t a b l i s h e d before the immigrant a r r i v e d i n B.C. or Canada. 93 TABLE 11 Contrast R a d i o l o g i c a l Diagnoses amongst the Refugee Immigrants and Native Indians R a d i o l o g i c a l Diagnoses Refugees (X) ( 1 > N a t i v e Indians 1 1 1 ) 1976 (2) 1977 (%) 1978 (%) Primary ...87 ..58 6 1. . .55 21) j ...59 Minimal ! 47j i 44J 49) • i 38J Moderate 7 20 21 17 Far Advanced 6 10 13 13 Others - 12 11 10 100 100 100 100 Footnote: ( i ) See Appendix 1, Table A2.(page 107) ( i i ) Information e x t r a c t e d from records o f Dept. o f Indian Health, Willow Chest C l i n i c , 807 W. 10th Ave., Vancouver, B. C. 94 screening took place i n the refugae camps. Chest x-ray would not be part of the pre-immigration screening for the s i x prospective immigrants under eleven years of age. 8.8 Early Disease Pattern Suggesting Recent Infection Pulmonary Tuberculosis progresses at a variable pace from i n f e c t i o n to primary active to minimally active to moderately active to f a r advanced disease. The e a r l i e r stages of the disease may be suspected c l i n i c a l l y but are confirmed by p o s i t i v e mantoux skin test, chest x-rays with symptoms and signs of active tuberculosis, and f i n a l confirmation by the demonstration of M. tuberculosis on culture. Eighty-seven percent of the chest x-rays on the refugee immig-rants with signs i n d i c a t i v e of Pulmonary Tuberculosis were interpreted as primary active or minimally a c t i v e . It was hypothesized on Page 26 that, i n many of the cases of Pulmon-ary Tuberculosis among the refugee immigrants, i n f e c t i o n took place subsequent to the pre-immigration screening and incubation of the disease occurred during the i n t e r v a l from pre-immigration screening to p o s t - a r r i v a l re-screening i n B r i t i s h Columbia. The percentage of x-rays c l a s s i f i e d as primary active or minimally active Pulmonary Tuberculosis suggests recent i n f e c t i o n a f t e r the pre-immigration screening as the reason for the high prevalence of disease among those refugee immigrants over eleven years of age. 95 9 Estimation of the Extra Public Health Hazard Due to Admission of Refugee Immigrants with Pulmonary Tuber-c u l o s i s Pulmonary Tuberculosis i s spread by an index case exhaling A i - i • « - • • M ^ - K i • (H6, 117, 118) droplet nuclei containing M. tuberculosis. ' ' Two cases of Pulmonary Tuberculosis confirmed by culture were present among the 3,125 refugees screened up to May, 1980. For the 10,000 refugees due to arrive by December, 1980, the expected number of cases confirmed b a c t e r i o l o g i c -a l l y would be: , 2 X 10,000 , _ — 3 } 1 2 5 = b Assume that the 278 cases of Pulmonary Tuberculosis i n the general population confirmed b a c t e r i o l o g i c a l l y i n 1978 were a l l active simultaneously. The p o s s i b i l i t y of contact for any one member of the public would be: 278 ' . . . . 2,500,000 Estimated population of B r i t i s h Columbia, 1978* 1 1' = 11.12 : 100,000 Additional r i s k with introduction of 10,000 refugee immig-rants 278 + 6 • • = 2,500,000 + 10,000 = 284 2,510,000 = : 11.31 : 100,000 Estimated extra r i s k with admission of 10,000 refugees Footnotes: ( i ) & ( i i ) Annual Report, D i v i s i o n Tuberuclosis Control, B. C , 1978 96 = 11 . 31 - 11 . 12 per 100,000 = 0.19 : 100,000 i . e . <2 : 1,000,000 Ten thousand refugee immigrants admitted to B r i t i s h Columbia would r e s u l t i n an immediate extra public health r i s k from Pulmonary Tuberculosis of less than two chances per m i l l i o n for each i n d i v i d u a l of the general public. The immediate extra public health r i s k i s minimal. Over one year, the calculated extra r i s k i s seven hundred and t h i r t y per m i l -l i o n - s t i l l minimal. The rescreening process has i d e n t i f i e d refugee immigrants with early disease. Spontaneous remission would occur i n 50 - 807, of the cases i d e n t i f i e d . The remaining 20 - 507, would progress to advanced disease and add to the future public health hazards. The refugee immigrants have demonstrated a rate of Pulmonary Tuberculosis confirmed by culture s i x times the rate seen i n the general population, and about 257. more than the rate seen i n non-refugee Asian immigrants. Native Indians display a proportionately higher immediate public hazard. The per-centage of cases with sputum demonstrating. M.; tuberculosis on culture among native Indians i s three times the rate of such cases among refugee immigrants. Because prospective immigrants under 11 years of age are not x-rayed before a r r i v a l i n Canada, refugee immigrants have a higher pro-portion of cases with chest x-rays i n d i c a t i n g early 97 tuberculosis. Some of these cases would progress to ad-vanced disease, i f not treated, and would become a more serious public health hazard. The conclusion i s - An e f f e c t i v e screening program would reduce the public health hazards of Pulmonary Tuberculosis associated with the high r i s k refugee immigrants from South-east Asia even though the d i r e c t r i s k to i n d i v i d u a l members of the general public i s minimal. While the objective of ther-study was to i d e n t i f y the public health r i s k from Pulmonary Tuberculosis among the refugee immigrants, the public health r i s k from non-refugee Asian immigrants i s s i m i l a r and the immediate health r i s k from registered native Indians i s three times as high. 8.10 Summary On r a d i o l o g i c a l findings, refugee immigrants demonstrate a prevalence of Pulmonary Tuberculosis six times the max-imum estimated prevalence among the non-refugee Asian immig-. rants and 1.2 - 2.2 times the estimated prevalence among registered native Indians. Comparing rates of cases of Pulmonary Tuberculosis confirmed by culture of M. tuberculosis, the refugee immigrants demon-strate a rate of bacteriologically-confirmed cases six times that among the general population, an equal rate with that 98 of non-refugee Asian immigrants, and about one t h i r d the rate among registered native Indians. The percentage of cases of Pulmonary Tuberculosis among the refugee immigrants i d e n t i f i e d by the re-screening program suggests i n d i v i d u a l refugee immigrants may have been in f e c t e d subsequent to the pre-immigration screening. The cal c u l a t e d 'extra' r i s k of Pulmonary Tuberculosis to the general public from admission of the 10,000 refugee immigrants i s about two chances i n one m i l l i o n . While the extra r i s k of Pulmon-ary Tuberculosis i s minimal, an e f f e c t i v e screening, program would reduce the public health hazard of Pulmonary Tubercul-osis from the refugee immigrants to almost zero. 99 9. Conclusions and Recommendations The minimal actual public health r i s k of Pulmonary Tubercul-osis from the Southeast Asian refugee immigrants would be further reduced by e f f e c t i v e screening programs. Implement-ation of the recommended changes would involve p o l i t i c a l decisions. 9.1 Pre-Immigration Screening It i s the Federal Department of Health and Welfare's respon-s i b i l i t y to ensure immigrants do not have communicable d i s -eases c o n s t i t u t i n g a public health hazard. The pro v i s i o n of health services to landed immigrants i s a p r o v i n c i a l r e s p o n s i b i l i t y . This d i v i s i o n of r e s p o n s i b i l i t i e s , p a r t i c -u l a r l y i n regard to refugee immigrants, has created problems. The routine pre-immigration screening of immigrants, apart from refugee movements, has been s a t i s f a c t o r y . Few cases of active Pulmonary Tuberculosis have arrived i n B r i t i s h Columbia undetected. The mass movement of refugees has demonstrated the i n a b i l i t y of the routine pre-immigration screening to cope with emergency situations quickly and • e f f i c i e n t l y . 9.2 Recommendations 9.2.1 Alternative 1 The decision to admit 50,000 refugees to Canada was p o l i t -i c a l and humanitarian. Once the decision was made, the 100 50,000 refugees should be s u p e r f i c i a l l y screened to ident-i f y urgent medical problems and then transported to Canada where thorough medical screening could be performed. Commun-icable diseases, such as Pulmonary Tuberculosis, would be a p r i o r i t y . I d e n t i f i c a t i o n of disease for treatment and not f o r expatriation would be the aim. Screening for Pulmonary Tuberculosis would be: 1) Physical examination 2) Skin t e s t i n g by Mantoux on ALL. 3) ALL over 11 years - chest x-ray 4) ALL under 11 years with p o s i t i v e Mantoux, or c l i n i c a l i ndications - chest x-ray 5) Sputum culture from a l l indiv i d u a l s whose chest x-rays interpreted as suspicious of Pulmonary Tuberculosis 6) Chemoprophylaxis would be offered to a l l refugee immig-rants under 35 years of age with positive Mantoux not receiving t r i p l e therapy for active tuberculosis 7) Individuals over 35 years and a l l others on chemopro-phylaxis would be followed for minimum of three years 8) B.C.G. scar should be discounted Canada has the resources, both f i n a n c i a l and medical, to accept and treat 50,000 refugees. There would be no public health hazard from Pulmonary Tuberculosis i f 'p a t r i a t i o n and medical examination i n Canada' was part of the p o l i t i c a l d e c ision to accept refugees. 101 9.2.2 Al t e r n a t i v e 2 The i d e a l i s hot often p o l i t i c a l l y acceptable. (Theoretic-a l l y , pre-immigration medical screening should i d e n t i f y a l l . c a s e s of active Pulmonary Tuberculosis. The comparison of rates between Asian refugees and non-refugee Asian immig-rants demonstrated s i m i l a r estimated prevalences of Pulmon-ary Tuberculosis. To improve the e f f i c i e n c y of the e x i s t i n g pre-immigration screening: 1) A l l prospective immigrants from countries with a higher prevalence of tuberculosis (of a l l forms) than the gen-e r a l population of Canada should have Mantoux skin t e s t i n g . 2.) Immigrant childre n under 11 years of age with p o s i t i v e Mantoux test should have chest x-ray. 3) Individuals under 35 years of age with p o s i t i v e Mantoux test and no other i n d i c a t i o n of active Pulmonary Tuber-c u l o s i s should be offered chemoprophylaxis with i s o n i a z i d and followed for three years. Those individuals with p o s i t i v e Mantoux test over 35 years of age should be followed f o r three years. 4) The presence of B.C.G. scar should be discounted^ 5) The chest x-ray should accompany the i n d i v i d u a l immig-rant to Canada and form part of the individual's records, as should the r e s u l t of the Mantoux test; both should be a v a i l a b l e f o r review by p r o v i n c i a l consultants. 9.2.3. Alternative 3 Both Alt e r n a t i v e 1 and 2 require federal co-operation and, 102 as quoted from Dr. A. Larsen (Page 1), "Federal au t h o r i t i e s are not prepared to make any changes i n t h e i r present p o l -i c i e s or procedures." Rescreening of the refugee immigrants on a r r i v a l i n Canada i s the t h i r d a l t e r n a t i v e . F a i l u r e of Federal co-operation prevented t h i s being accomplished at the Refugee Reception Centre i n Edmonton, Alberta. A c e n t r a l i z e d rescreening program would necessitate transport to a s i t e capable of accommodating 200 - 300 refugees f o r three days at a time, and providing f a c i l i t i e s f o r Mantoux t e s t i n g , chest x-ray, and sputum cult u r e . Screening would follow the same format otulined under Alt e r n a t i v e 2. 3 Advantages of Centralized Rescreening The rescreening program introduced i n B r i t i s h Columbia at-tempted to i d e n t i f y and screen 10,000 refugees scattered i n several hundred d i f f e r e n t communities throughout the province. In May, 1980, 3,125 out of 5,100, i . e . 61% of the refugees, had been contacted and persuaded to be r e -screened. Some i n d i v i d u a l immigrants, f e e l i n g threatened by the p o s s i b l i t y of expatriation, refused rescreening. The costs involved i n pursuing the 39% not re-screened by May, 1980, suggest that 100% of the refugee immigrants w i l l not be rescreened. Those most at r i s k may refuse. In contrast, transport to a ce n t r a l i z e d s i t e as part of the V 1 0 3 routine admission procedure would enable rescreening of I 0 0 7 o of the refugees a r r i v i n g i n B r i t i s h Columbia. The format presented under Alternative 2 would i d e n t i f y c h i l d r e n under 1 1 years of age with early active disease. Adults with early disease a f t e r i n f e c t i o n , subsequent to the pre-immigration medical, would also be i d e n t i f i e d . Adequate int e r p r e t e r services would encourage compliance with chem-oprophylaxis. The subsequent follow-up of the 4 0 - 5 0 ex-pected active cases of Pulmonary Tuberculosis would involve minimal e f f o r t i n contrast to the e f f o r t needed to f i n d and encourage 1 0 , 0 0 0 refugee immigrants scattered through-out the province to undergo rescreening. The acceptance of a number of refugees, t h e i r p a t r i a t i o n to Canada, and adequate screening and treatment of diagnosed disease a f t e r a r r i v a l i s the humane recommendation. In the absence of Federal co-operation, c e n t r a l i z e d rescreening a f t e r a r r i v a l i s the a l t e r n a t i v e recommendation which w i l l achieve the same r e s u l t at a higher t o t a l cost. 9 . 4 Confirmation of Hypothesis The rate of Pulmonary Tuberculosis occurring among the r e f -ugee immigrants confirms the hypothesis that a rescreening program was warranted. With the Federal/Provincial impasse about the necessity of a rescreening program f o r the refugee immigrants preventing co-operation, the rescreening program for Pulmonary Tuberculosis would have been more e f f e c t i v e i f performed at one ce n t r a l i z e d l o c a t i o n within B r i t i s h 104 Columbia. A ce n t r a l i z e d rescreening program would have minimized the public health hazards of Pulmonary Tuberculosis among the refugee immigrants from Southeast Asia to B r i t i s h Columbia. . 5 Summary The public health hazards a r i s i n g from the admission of 50,000 refugees to Canada would be minimal i f the refugees were pat r i a t e d to Canada and medically screened f o r commun-icab l e disease a f t e r a r r i v a l i n Canada. Viable a l t e r n a t i v e s to p a t r i a t i o n and screening a f t e r a r r i v a l would be: 1) More complete pre-immigration screening overseas, i n c l u d -ing Mantoux on a l l immigrants and chest x-ray of any c h i l d under 11 years with a posi t i v e Mantoux. 2) Centralized rescreening of refugee immigrants bound fo r B r i t i s h Columbia with s i m i l a r provisions as stated i n A l t e r n a t i v e (1) above. The hypothesis that 'rescreening of the refugeej immigrants for Pulmonary Tuberculosis was warranted' was confirmed. Centralized rescreening within B r i t i s h Columbia would have been more e f f e c t i v e i n minimizing the public health hazard of Pulmonary Tuberculosis among the Southeast Asian refugee immigrants to B r i t i s h Columbia. 105 APPENDIX I Table A l C a l c u l a t i o n A g e - S p e c i f i c Incidence Pulmonary T u b e r c u l o s i s i n General Population - B. C. 1976, 1977, 1978 - (Rates per 100,000)  Age Bracket 1976 1977 1978 No. Incidence No. Incidence No. Incidence 0 - 1 4 26 4.2 15 2.5 36 6.1 15 - 24 36 23 5.0 43 9.2 25 - 44 87 12.8 93 13.8 83 12.0 45 - 64 93 19.3 91 18.4 95 18.9 65+ 72 31.1 70 28.6 87 34.5 314 12.8 292 11.7 344 13.8 Method of C a l c u l a t i o n : From the Annual Reports of the B. C. T u b e r c u l o s i s D i v i s i o n . The number of cases o f Pulmonary T u b e r c u l o s i s s p e c i f i c to each age bracket was e x t r a c t e d . The p r o p o r t i o n of Pulmonary T u b e r c u l o s i s T o t a l T u b e r c u l o s i s Cases was c a l c u l a t e d and t h i s p r o p o r t i o n o f the i n c i d e n c e rate was a t t r i b -uted to pulmonary t u b e r c u l o s i s so: 106 Annual Report, 1978 Table 23 Number of cases Pulmonary Tuberculosis in 0 - 14-yr. age bracket = 36 Table 18A All active cases 0 - 14-yr. age bracket =39 and incidence rate for all active cases = 6.6. Incidence rate for Pulmonary Tuberculosis in age bracket 0 - 14 yrs. in Table 5 = | | X 6.6 =6.1 Table A3 Calculation of Effects of Spontaneous Healing of Pulmonary Tuberculosis Classified Radiologically "Primary" or "Minimally" Active Among Refugee Imrtifgr as m g ants Radiological No. of,y Probable No. of Probable Classification Cases^ ' Spontaneous = Cases Cases Healing' 1 1) Healing Progressing Primary 6 80% 4.8 1.2 Minimal 7 50% 35 3.5 Others 2 - 2.0 Total 15 6.7 Adjusted rate per 100,000 = ^ f f g O i i ) = 217/100,000. Footnotes: (i) Table A2, page 107 (ii) Page 71, paragraph 4 ( i l l ) Total number rescreened, Appendix 2, page 108. 107 APPENDIX I Table A2 R a d i o l o g i c a l Diagnoses - New A c t i v e Pulmonary T u b e r c u l o s i s i n the Refugee Immigrants and General P o p u l a t i o n , B.C. 1976, 1977, 1978  Refugee Immigrants 1976 1977 1978 # % # % 7T % # % Primary 6 40 32 10 15 5 43 12 Minimal 7 47 132 42 125 43 141 41 Moderately Advanced 1 7 66 21 81 28 79 23 Far Advanced 1 6 42 13 42 14 47 14 Other - 42 14 29 10 34 10 T o t a l 15 100 314 • 100 292 100 344 100 Source: Willow Chest C l i n i c and Annual Reports, D i v i s i o n o f T u b e r c u l o s i s C o n t r o l , B. C , f 1976, 1977, 1978 1G8 APPENDIX 2 D e r i v a t i o n o f A g e - s p e c i f i c Rate o f Pulmonary T u b e r c u l o s i s Amongst the Refugee Immigrants , June 1, 1979 - May 1, 1980 , Dr. A. Heimann, F i e l d E p i d e m i o l o g i s t with the B. C. P r o v i n c i a l Government, c i r c u l a t e d a l e t t e r o f enquiry to the health u n i t s A p r i l , 1980 Appendix 5 Responses to h i s l e t t e r (Table A6) Computer L i s t 11/6/80 (Table A7) From Table A6 T o t a l number refugee immigrants rescreened May, 1980 3,125* Table A4 Number o f Refugee Immigrants i n Each Age Group Rescreened Age % va r i o u s age brackets Tot a l No. screened In from Table A7 No. screened per age aroup Years (Table A6) *" 0-4 13.1 5-9 10.7 10-14 9.6 15-19 13.3 20-24 17.9 25-29 13.0 30-34 6.8 35-39 4.9 40-44 2.7 45-49 2.6 50-54 3.3 55-59 0.8 60-64 0.9 65+ .04 3,125* = 410 = 335 300 1,045 416 559 975 406 213 153 84 856 81 103 25 28 ' 237 12 12 109 APPENDIX 2 Table A5 C a l c u l a t i o n A g e - S p e c i f i c Rate T u b e r c u l o s i s Amongst Refugee Immigrants 1979/80 Age Range Number o f Cases Pulmonary T u b e r c u l o s i s per Age Range (Table 11) Rescreened Population per Age Range (Table A4) Rate Pulmonary T u b e r c u l o s i s per 100,000 0 - 14 6 1,045 574 1 5 - 2 4 2 975 205 25 - 44 6 856 700 45 - 64 - 237 -65+ 1 12 Population r e -screened too small f o r s i g -n i f i c a n c e O v e r a l l 15 3,125 480 110 APPENDIX 2 Table A6 Number o f Immigrants Rescreened May, 1980 Health U n i t s ' Response to Dr. A. Heimann's Request re Screenina Health D i s t r i c t No. o f Refugees i n D i s t r i c t No. Having Had T u b e r c u l i n Skin Test East Kootenay 64 58 West Kootenay 41 37 North Okanagan 121 89 South Okanagan 183 183 Ce n t r a l F r a s e r V a l l e y 112 (Est) 101 Upper F r a s e r V a l l e y 411 398 South C e n t r a l 115 115 Boundary 239 222 Simon F r a s e r 164 164 C a p i t a l Region, V i c t o r i a 241 172 M e t r o p o l i t a n Vancouver 2,200 554 Burnaby 296 274 Richmond 86 50 Cen t r a l Vancouver I s l a n d 147 87 Upper Vancouver I s l a n d 105 101 Cariboo 16 16 Skeena 174 167 Peace R i v e r 81 64 Northern I n t e r i o r 164 (Est) 150 S e l k i r k 44 (Est) 40 Coast G a r i b a l d i 37 (Est) 33 North Shore 59 ( E s t ) 50 T o t a l 5,100 3,125 = 61% For those u n i t s not r e p l y i n g , screening was estimated a t 90% o f refugees i n area approximately the same rate as other Health Units ( e x c l u d i n g Vancouver). I l l APPENDIX 2 Table A7 Computer L i s t , Age/Sex Breakdown of Refugee Immigrants Having A r r i v e d i n B r i t i s h Columbia up to June 11, 1980 Age Sex Unknown M F T o t a l % 0 - 4 11 337 323 671 13.1 5 - 9 7 250 287 544 10.6 10 - 14 4 219 266 489 9.6 1 5 - 1 9 7 283 394 684 13.3 20 - 24 13 390 512 915 17.8 25 - 29 9 328 328 665 13.0 30 - 34 3 138 203 344 6.8 35 - 39 2 99 150 251 4.9 40 - 44 2 65 67 134 2.7 45 - 49 64 68 132 2.6 50 - 54 1 82 82 165 3.3 55 - 59 26 15 41 0.8 60 - 64 3 27 16 46 0.9 65+ 16 6 22 0.4 Age unknown 5 3 4 12 0.2 T o t a l 67 2,327 2,721 5,115 100.0 112 APPENDIX 3 D e r i v a t i o n of Age S p e c i f i c Population Groupings f o r A s i a n Immigrants bound f o r B.C. Table A8 "Country Of l a s t permanent r e s i d e n c e " was e x t r a c t e d from immigration s t a t i s t i c s (Page 114) f o r 1976, 1977, and 1978. From t h i s c h a r t i t was c a l c u l a t e d t h a t A s i a n Immigrants formed 43% (1976) 42% (1977) and 43% (1978) of the t o t a l immigrants coming to Canada. Table A9 "Age of immigrants bound f o r B.C." was e x t r a c t e d from immigration s t a t i s t i c s (Page 115) f o r 1976, 1977, and 1978 C a l c u l a t i o n : By a p p l y i n g the percentage of A s i a n immigrants from Table A8 to the s t a t i s t i c s given i n A9 Table A10 was compiled so: Table A8 % Asian immigrants to Canada 1976 (43%), 1977 (42%), 1978 (43%). T a b l e A9 Immigrants bound f o r B.C. Age 1976 1977 1978 0-4 1530 989 ' 665 Table A10 Age 1976 1977 1978 0-4 1530 x 43 989 x 42 665 x 43 100 100 100 = 658 = 415 = 286 113 Table A l l i s i n t u r n a summary of Table A10. 114 APPENDIX 3 Tabl e A8 Immigration s t a t i s t i c s C.E.I.C. MP 22-1/76-78 Country o f l a s t permanent residence of immigrant d e s t i n e d f o r B.C. Country 1976 1977 1978 % % % Europe 5341 26 4360 28 3424 28 A f r i c a 1001 5 710 5 469 4 A s i a 8785 43 6477 42 5248 43 A u s t r a l i a 652 3 448 3 425 3 North & Ce n t r a l America 2970 14 2208 14 1880 15 C a r i b b e a n 376 2 228 1 196 2 South America 463 3 367 3 313 2 Oceania & Other Oceanic Islands 896 4 537 4 373 3 Not s t a t e d 3 ~ Grand T o t a l 20484 100 15395 100 12331 100 Source: Immigration S t a t i s t i c s Canada Employment and Immigration Commission MP 22-1/76-78(121) 115 APPENDIX 3 Table A9 Age o f immigrants bound f o r B.C. ARE 1976 1977 1978 0 - 4 1530 989 665 5 - 9 1727 1186 804 10 - 14 1501 1048 749 15 - 19 1639 1340 1142 20 - 24 3084 2458 1990 25 - 29 3162 2447 1886 30 - 34 1872 1472 1116 35 - 39 1194 805 637 40 - 44 783 513 379 45 - 49 588 409 344 50 - 54 605 403 394 55 - 59 631 518 499 60 - 64 912 730 717 6 5 - 6 9 612 523 461 70 +•• 644 554 • 548 20484 15395 12331 Source: Immigration S t a t i s t i c s Canada Employment and Immigration Commission MP 22-1/76-78(121) 116 APPENDIX 3 Table A10 Asian Immigrants to B r i t i s h Columbia 1976-78 According to Age Grouping AGE 1976 1977 1978 0 - 4 658 415 286 5 - 9 743 498 346 10 - 14 645 440 322 0 - 1 4 2046 1353 954 15 - 19 705 563 491 2 0 - 2 4 1326 1032 855 15 - 24 2031 1595 1346 25 - 29 1360 1028 810 30 - 34 805 618 480 35 - 39 513 338 274 4 0 - 4 4 337 215 163 25 - 44 3015 2199 1727 4 5 - 4 9 253 172 148 5 0 - 5 4 260 169 169 55 - 59 271 '218 215 6 0 - 6 4 392 306 308 45 - 64 1176 865 840 65 + 540 452 434 65 + 540 452 434 TOTAL 8808 6464 5301 43% of = 42% of = 43% of 20484 15395 12331 117 APPENDIX 3 From Table 3 Table A l l Age Groupings of Asian Immigrants to B.C. Age Group 1975 1977 1978 0 - 14 2046 1353 954 1 5 - 2 4 2031 1595 1346 25 - 44 3015 2199 1727 45 - 64 1176 865 840 65 + 540 452 434 T o t a l 8808 6464 5301 Source: Table A10 Page 116 APPENDIX 3 Table A12 Cases of pulmonary t u b e r c u l o s i s o c c u r r i n g amongst Asian immigrants i n f i r s t 12 months i n B. C. adjusted f o r place of i n i t i a l d i a g n o s i s ( i n B. C. or Ex B. C.) f o r years 1976-1977 and 1978. Age Group 1976 1977 1978 Diagnosed i n B.C. Ex B.C. Total Diagnosed in B.C. Ex B.C. T o t a l Diagnosed i n B.C.; Ex B.C. Total 0 - 14 - 3 - 3 - - -15 - 24 1 ' 2 3 1 2 3 1 1 2 25 - 44 - 5 5 2 2 4 2 1 3 00 45 - 64 1 4 5 1 1 1 4 5 65 + 1 8 9 2 1 3 - 2 2 Total . 3 19 22 8 6 14 4 8 12 Source: Extracted from records D i v i s i o n of T u b e r c u l o s i s Control Vancouver, B . C . 1 1 9 APPENDIX 3 Table A13 Age s p e c i f i c incidence of Pulmonary Tuberculosis amongst Asian Immigrants with i n i t i a l Diagnosis being made i n B.C. within 12 months of immigrant's a r r i v a l i n the Province f o r years 1976, 1977, 1978 AGE 0 - 14 15 - 24 25 - 44 45 - 64 65 + i/) CU CM V) i — ro <C CJ 4-O CU 1976 C i — O i — •r- cu <c +-> cn ta m <u] o . cu ta O Q-h-1P-2046 2031 3015 1176 540 8808 cu Q. CU CJ o c o CL) S~ O •o <u » •r- Q.O o o C r — 49 85 185 34 un CU CM 10 i — ta CJ cu 4- r — O -Q ta 3 1 2 1977 C r — O <— • i - <U<C 4-> cn ta m at 3 S - S e c u ta o cu— o . 1353 1595 2199 865 452 8 6464 cu CJ o c: o cu s~ o " a CD « • r - Q.O o o 222 73 90 442 124 in CU CM CO I — ta <c cu 4- r — O XI O r— 1 9 7 8 C r — O r — •i-CU <C 4-> CD roro CU O-CU ro O Q i l — C L . 954 T346 1727 840 434 5301 cu CJ o c o a> s- o •o cu « •r~ Q.O CJ o c i — 74 116 119 75 This Table excludes a l l cases of pulmonary tuberculosis where an Asian Immigrant was admitted under surveillance or minister's permit for suspected tuberculosis. In contrast Table Al2 includes a l l cases of pulmonary tuberculosis occurring amongst Asian Immigrants within 12 months of a r r i v a l i n B.C. APPENDIX 4 Table A14 Age - S p e c i f i c Incidence of Pulmonary T u b e r c u l o s i s Amongst Re g i s t e r e d Indians 1976 1977 1978 Age Bracket No. of Cases + Population * Incidence per 100,000 No. of Cases + Population * Incidence per 100,000 No. of Cases + Population * Incidence per 100,000 0 - 14 6 20,375 29.3 2 20,995 9.5 15 21,092 71.1 1 5 - 2 4 9 13,388 67.2 1 13,553 7.4 16 13,858 115.5 25 - 44 20 12,695 157.5 25 12,904 193.7 24 13,140 182.6 45 - 64 12 '. 4,961 241.8 14 5,185 270.0 16 5,244 305.1 65 + 12 1,923 624.0 5 2,116 236.3 13 1,833 690.7 59 53,342 110.6 47 54,753 85.8 84 55,217 152.1 Source: + D i v i s i o n of Tu b e r c u l o s i s Control Annual Reports - 1976/77/78 * and Dept. of Indian A f f a i r s , Health & Welfare Canada 121 APPENDIX 5 ALL MEDICAL HEALTH OFFICERS A p r i l 23, 1980 Re: Refugee Screening Program I am compiling i n f o r m a t i o n on the r e s u l t s of the refugee s c r e e n i n g program so t h a t a r e p o r t o f the program can be given at H e a l t h O f f i c e r s 1 C o u n c i l . I am c o l l e c t i n g i n f o r m a t i o n on t u b e r c u l o s i s t e s t i n g , s y p h i l i s s e r o l -ogy t e s t i n g , h e p a t i t i s t e s t i n g , and p a r a s i t e examinations. Though I am c o l l e c t i n g t h i s information from TB C o n t r o l , VD C o n t r o l , and the P r o v i n c i a l Labs, I would l i k e to confirm whether such i n f o r m a t i o n bears any resemblance to the work t h a t the l o c a l health d i s t r i c t s are doing i n the f i e l d . To t h i s end, I would a p p r e c i a t e i t i f you could supply me w i t h the f o l l o w i n g i n f o r m a t i o n : 1. The number of refugees you have i n your area from your records. 2. the number o f refugees contacted by your h e a l t h d i s t r i c t o r department. 3. The number o f people who have r e c e i v e d any o f the i n d i c a t e d examinations: a) s y p h i l i s s e r o l o g y b) TB s k i n t e s t c) p a r a s i t e examination d) h e p a t i t i s t e s t ( i f any done l o c a l l y ) Please f e e l f r e e to put the numbers on t h i s form i f i t w i l l save you some time. Thank you f o r your a s s i s t a n c e . G. A. Heimann, M.D. . . Federal F i e l d E p i d e m i o l o g i s t - B. C . ( 1 ? 0 ' c c : Dr. F. White Dr. R. Mathias Dr. F. D. Mackenzie 122 References Grzybowski, S.: Evaluation of the Tuberculosis Problem and Control Measures i n Canada. p 3. Department of Medicine, University of B r i t i s h Columbia, Vancouver, B. C , 1979. Larsen, A.: Indo-Chinese Refugees as a Source of Imported Chronic Communicable Disease. Report from B. C. Epidemiologist to Ad Hoc Committee of B.C. Min-i s t r y of Health, September, 1979. A l l e n , E. A.: Personal Communication. Director, D i v i s i o n of Tuberculosis Control. W. 10th Ave., Vancouver, B.C. op. c i t . 1, p 1• McMahon, B. and Pugh, T.: Epidemiology - P r i n c i p l e s and Methods, 8th E d i t i o n , pp 60 - 81. L i t t l e Brown, Boston, 1970. Ibid. Annual Report 1978. D i v i s i o n of Tuberculosis Control, W. 10th Ave., Vancouver, B. C. bp. c i t . 2, p 2. Benenson, A. S.: Control of Communicable Diseases i n Man. p 383. 12th E d i t i o n , American Public Health Association, Washington, D. C , 1975. I b i d . Hoeprich, P. D.: Chemoprophylaxis of Infectious Dis-ease, p 207. Infectious Diseases, Harper & Row, New York, 1972. Concise Oxford Dictionary, p 243. 4th E d i t i o n , Oxford, 1950. S t a t i s t i c s Canada. Immigration, Emigration, Inter-P r o v i n c i a l Migration and Natural Increase on an Annual Basis. Extracts from Case Reports, 1976-1978. Immigration S t a t i s t i c s . Canada Employment and Immig-ra t i o n Commission. MP 22-1/76-78. 123 16. Enarson, D.; Ashley, M. J . , Grzybowski, S.: Tubercul-osis i n Immigrants to Canada. A Study of Present Day Patterns i n Relation to Immigration Trends and Birthplace. American Review of Respiratory Disease. 119, 11-17, 1979. 17. Ibid.:, p 16. 18. Ibid . , p 13. 19. American Thoracic Society. Preventive Therapy of Tuberculosis Infection. American Society of Respir-atory Disease. 110, 371-373, 1974. 20. Hess, E. V. and McDonald, N.: Pulmonary Tuberculosis i n I r i s h Immigrants and i n Londoners; Comparison of Hospital Patients. Lancet 2, 132, 1954. 21. Springett, V. H.; Adams, J.C.S.; D'Costa, T. B.; Hemming, M.: Tuberculosis i n Immigrants i n Birmingham. 1 1956-1957. B r i t i s h Journal of Preventive and Social Medicine. 12, 135, 1958. 22. Stevenson, D. K.: Tuberculosis i n Pakistanis i n Bradford. B r i t i s h Medical Journal. 1, 1382, 1962. 23. Ibid . , p 1382. . 24. Vennema, A.: Tuberculosis i n Rural Vietnam. Tubercle 52, 49, 51, 1971. 25. 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J . : The Tuberculin Skin Reaction i n Active Pulmonary Tuberculosis. Amer-ican Review of Tuberculosis and Pulmonary Diseases. 78, 399-402, 1958. 125 50. Keck, C. W.; St. John, R. K.; Daniel, T. M.: Tubercul-osis i n the Yungas Area of B o l i v i a . Health Services Report. 88, 499-507, 1973. 51. American Thoracic Society Diagnostic Committee on . Skin Testing. The Tuberculin Skin Test. American Review of Respiratory Diseases. 104, 769-755, 1971. 52. Grzybowski, S.; Brown, M. T.; and Stothard, D.: In-fections with A t y p i c a l Mycobacteria i n B r i t i s h Columbia. Canadian Medical Association Journal. 100, 896, 1969. 53. Hsu, T. L.: Diagnostic Skin Test for Mycobacterial Infection i n Man. Chest 64, 1,2, 1973. 54. Fogan, L.: PPD Antigens and the Diagnosis of Mycobac-t e r i a l Disease. Archives of Internal Medicine 120, 49-54, 1969. 55. Comstbck, G. W.: False Tuberculin Test Results. Chest (Supplement) 68, 465-469, 1975. 56. Thompson, J . J . ; Classroth, J . L.; Snider, D. E.: The Booster Phenomenon i n S e r i a l Tuberculin Testing. American Review of Respiratory Diseases. 119, 587-595, 1979. 57. Holden, M.; Dubin, M. R.; and Diamond, P. H.: Fre-quency of Negative Intermediate Strength Tuberculin S e n s i t i v i t y i n Patients With Active Tuberculosis. New England Journal of Medicine. 285: 1506-1509, 1971. 58. S n e l l , N.J.C.: A Comparison of Mantoux and Tuberculin Tine Testing i n a Chest Unit. Tubercle 60, 99-104, 1979. 59. op. c i t . 57, p 1508. A 60. Grzybowski, S.; Kincade, G. F.; McLean, C. C ; Rowe, J. F.: Size of Tuberculin Reactions i n Various Age Groups. American Review of Respiratory Disease. 98, 2, 303-305, 1968. 61. Ibid., p 304. 62. Ibid., p 305. 63. op. c i t . 1, p 12. 64. Grzybowski, S.; Galbraith, J. D.; Dorken, E.: Chemo-prophylaxis T r i a l i n Canadian Eskimos. Tubercle 57, 163-69, 1976. 126 65. op. c i t . 33, p 1520. 66. op. c i t . 1, p 5. 67. op. c i t . 16, p 13. 68. op. c i t . 1, p 3. 69. American Thoracic Society, American Lung Association, Center f o r Disease Control. Preventive Therapy of Tuberculous Infection. American Review of Respiratory Disease. 110, 371, 1974. 70. bp. c i t . 11, p 207. .71. Blakely, D. L.; Imm, I. E.; Piszczek, E. A.; Francis, B. J . ; Grant, A. B.: Follow-Up on Drug Resistant Tuberculosis - M i s s i s s i p p i . Morbidity and Mortality Weekly Report. 27, 38, 356, 1978. 72. - U. S. Dept. of Health, Education and Welfare/Public Health Service. Health Status of Indo-Chinese Refugees. Morbidity and M o r t a l i t y Weekly Report. 28, 33, 387, 1979. 73. Eidus, L.; Jessamine, A. G.; Herschfield, E. S.; Helbecque, D. M.: A National Study to Determine the Prevalence of Drug Resistance i n Newly Discovered Previously Untreated Tuberculosis Patients as well as i n Retreatment Cases. Canadian Journal of Public Health. 69, 146, 1978. 74. Cheung, 0. T.: Drug Resistance i n Patients with Pul-monary Tuberculosis. Canadian Medical Association Journal. 113, 848-849, 1975. 75. Schiffman, P. L.; Ashkar, B.; Bishop, M.; and Cleary, M.G.: Drug Resistant Tuberculosis i n a Large Southern C a l i f o r n i a Hospital. American Review of Respiratory Disease. 116, 821-825, 1977. 76. Kopanoff, D. E.; Kilburn, J. 0.; Glassroth, J. L.; Snider, D. E.; Farer, L. S.; and Good, R. C.: Resis-tance i n the United States: March 1975 - November 1977. A United States Public Health Service Co-oper-ati v e Study. American Review of Respiratory Disease. 118, 835-842, 1978. 77. Byrd, R. B.; Fisk, D. E.; Glover, J. N.; Wilder, N. J . : Tuberculosis i n Oriental Immigrants. Chest 76, 2, 136-139, 1979. 127 78. M e i s s n e r , G.: I s o n i a z i d - R e s i s t e n t e Tuberkul-Obak-t e r i e n . Advances T u b e r c u l o s i s R e s e a r c h . 7, 52, 1956. 79. F a r e r , L. S.: P r e v e n t i n g T u b e r c u l o s i s . Comprehensive Therapy. 3, 45, 1977. 80. Comstock, G. W.; and Edwards, P. Q.: The Competing R i s k s o f T u b e r c u l o s i s and H e p a t i t i s f o r A d u l t Tuber-c u l i n R e a c t o r s . A m e rican Review of R e s p i r a t o r y D i s -e a s e s . I l l , 573, 1.975. 81. M o u l d i n g , T.: C h e m oprophylaxis o f T u b e r c u l o s i s -When i s t h e B e n e f i t Worth the R i s k and t h e C o s t . A n n a l s o f I n t e r n a l M e d i c i n e . 4, 761, 1971. 82. Edwards, P. Q.: I s o n i a z i d A s s o c i a t e d H e p a t i t i s . B u l l e t i n o f t h e I n t e r n a t i o n a l U n i o n A g a i n s t T u b e r c u l -o s i s . 51, 209, 1976. 83. I b i d . p. 209. . . . 84. B l a c k , M.: E d i t o r i a l - I s o n i a z i d and the L i v e r . A m e r ican Review of R e s p i r a t o r y D i s e a s e . 110, 1-3, 1974. 85. R i s k a , N.: H e p a t i t i s Cases i n I s o n i a z i d T r e a t e d Groups and i n a C o n t r o l Group. B u l l e t i n o f I n t e r n a t i o n a l U n i o n A g a i n s t T u b e r c u l o s i s . 51, 1, 207, 1976. 86. F a r e r , L. S.: C hemoprophylaxis A g a i n s t T u b e r c u l o s i s . C l i n i c s i n Chest M e d i c i n e . 1, 2, 206, 1980. 87. op. c i t . 85, p 207. 88. bp. c i t . 84, pp 1 - 3. 89. op. c i t . 82, p 209. 90. op. c i t . 86, p 206. 91. op. c i t . 86, p 206. 92. dp. c i t . 72, p 387 93. op. c i t . 86, p.207. 94. B e c k e r , M. H. ; and Maiman, D e t e r m i n a n t s o f Compliance w i t h H e a l t h and M e d i c a l Care Recommendations. M e d i c a l Care 13, 10-24, 1975. 95. D a v i s , M. S.: V a r i a t i o n s i n P a t i e n t s Compliance W i t h D o c t o r ' s O r d e r s . A n a l y s i s o f Congruence Between Survey Responses and R e s u l t s o f E m p i r i c a l I n v e s t i g a t i o n s . J o u r n a l o f M e d i c a l E d u c a t i o n . 41, 1037-1048, 1966. 128 96. Moulding, G. T.; Onstad, G. D.; and Sharbard, J . A.: Supervision of Outpatient Drug Therapy with the Medic-ation Monitor. Annals of Internal Medicine. 73, 559-564, 1970. 97. Ireland, H. D.: Outpatient Chemotherapy for Tubercul-o s i s . American Review of Respiratory Diseases. 82, 378-383, 1960. 98. Maddock, R. K.: Patient Co-operation i n Taking Medic-ines, A Study Involving Isoniazid and Aminosalicylic Acid. Journal of American Medical Association. 199, 167-172, 1967. 99. Curry, F. J . : Neighbourhood C l i n i c s f o r More E f f e c t i v e Out-patient Treatment of Tuberculosis. New England Journal of Medicine. 270, 1262-1269, 1968. 100. Shroeder, S. A.: Lowering Broken Medical Appointments at a Medical C l i n i c . Medical Care 11, 72-74, 1973. 101. B l a c k n e l l , B.: Treatment Adherence. B r i t i s h Journal of Psychiatry. 129, 513, 1976. 102. Caldwell, J . R.; Cobb, S.; Dowling, M. D.: The Drop-out Problem i n Anti-hypertensive Therapy. Journal of Chronic Diseases. 22, 579-592, 1970. 103. bp. c i t . 64. 104. Annual Reports 1976, 1977, 1978. D i v i s i o n of Tubercul-osis Control, Community Health Programs, B. C. Ministry of Health. 105. A l l e n , A. E.: Personal Communication. Director, Div-i s i o n of Tuberculosis Control, 807 W. 10th Ave., Vancouver, B. C. 106. Laberge, C : Personal Communication. Indian Health Consultant for Tuberculosis. National Health and Welfare, D i v i s i o n of Tuberculosis Control, 807 W. 10th Ave., Vancouver, B. C. 107. Bentley, F. J . : and Grzybowski, S.: Tuberculosis i n Childhood and Adolescence, p 16-19. National Association f o r Prevention of Tuberculosis, London W. C. 1, 1954. 108. Chao, Chuan-Wei: Spontaneous Healing of Pulmonary Tuberculosis Diagnosed Radiologically as 'Minimally Active'. Personal Communication 4/6/80. Willow Chest T r a v e l l i n g C l i n i c , Vancouver, B. C. 109. Grzybowski, S.: Personal Communication. Professor of Medicine, University of B r i t i s h Columbia Medical 129 School, Vancouver, B. C. 110. Ibid. 111. op. c i t . 1, p 3. 112. op. c i t . 2, p 2. 113. Birkelo, C. C ; Chamberlain, W. E.; Phelps, P. S.; Schools, P. E.; Zacks, D.; Yerushalmy, J . : Tubercul-osis Case Finding. American Medical Association Journal. 133, 6, 359-365, 1947. 114. op. c i t . 1, p 1. 115. bp. c i t . 2, p 2. 116. Wells, W. F.; R a t c l i f f e , H. L. ; Crumb, C : On the Mechanism of Droplet Nuclei Infection. American Journal of Hygiene. 47, 11, 1948. 117. R a t c l i f f e , H. L.; and Palladino, V. S.: Tuberculosis Induced by Droplet Nuclei Infection. Journal Experim-ental Medicine. 97, 61, 1953. 118. Ratcliffe:, H. L. : Tuberculosis Induced by Droplet Nuclei Infection. American Journal of Hygiene. 55, 36, 1952. 119. op. c i t . 79, p.45. 120. Heimann, G. A.: Federal F i e l d Epidemiologist, B. C. Ministry of Health, 1515 Blanshard Street, V i c t o r i a , B. C. Apl. 23, 1980. 121. Immigration S t a t i s t i c s , Canada Employment and Immig-ra t i o n Commission. MP 22-1/76-78. 130 Acknowledgements The patience and assistance o f Dr. J . R. Robinson, Dr. E. J . Bowmer, and Dr. M. Vernier, a l l of the University of B r i t i s h Columbia, i n reviewing and demonstrably improving this t h e s i s , and of Mrs. A l i c e C r i s t o f o l i of T r a i l , B. C , i n so pain takingly typing i t , i s g r a t e f u l l y acknowledged. Dr. N. M. Arnott 

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