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Canada Communicable Disease Report

Volume 27-19
1 October 2001

[Table of Contents]

CANADIAN GUIDELINES FOR THE INVESTIGATION AND FOLLOW-UP OF INDIVIDUALS UNDER MEDICAL SURVEILLANCE FOR TUBERCULOSIS AFTER ARRIVAL IN CANADA


These guidelines were prepared by the Immigration Subcommittee of the Canadian Tuberculosis Committee. They have been approved by the Canadian Tuberculosis Committee and the Canadian Thoracic Society and replace all previous versions, including the most recent one published in 1992(1). Part I provides background on the epidemiology of tuberculosis (TB) among the foreign-born and the rationale for medical surveillance. Part II describes the process of medical assessment of immigrants and refugees to Canada. Part III is a set of clinical and public health guidelines for the investigation and follow-up of individuals who have been placed under medical surveillance for TB after arrival in Canada.

Part I
Epidemiology of foreign-born cases of tuberculosis

In 1997 the World Health Organization (WHO) estimated the global burden of TB: 1.86 billion people around the world were infected with Mycobacterium tuberculosis and over 24 million people had active TB disease(2). Eighty percent of all new TB cases occurred in 22 countries, with more than half of the world's cases occurring in five Southeast Asian countries(2). About 95% of the 8 million new cases reported every year occur in the developing world(3).

With overall TB incidence declining in industrialized countries, the relative importance of imported TB has grown. The incidence of TB disease among the foreign-born has surpassed that of those born in the United Kingdom(4,5), New Zealand(6), Australia(7), western Europe(8), Israel(9), United States(10-12) and Canada(13).

TB in Canada had been steadily decreasing since the 1950s(13), but immigration has arrested this decline. As early as the 1970s, researchers were commenting on the rising importance of foreign-born TB in Canada(14). Since 1987 over 200,000 immigrants and refugees have come to Canada every year, with 95% of immigrants and refugees originating from TB-endemic countries(15). The proportion of TB cases in Canada that were foreign-born rose from 35% in 1980 to 64% in 1998(13). This increase is especially pronounced in provinces receiving the majority of new immigrants and refugees to Canada (Ontario and British Columbia)(13,15). Toronto, which received 48% of all immigrants to Canada in 199815, reported that 90% of their TB cases were foreign-born(16).

Canadian(17-21) and British(22) clinicians have noted the increased prevalence of drug-resistant strains of TB among the foreign-born for >= 2 decades. The recent WHO/International Union Against TB and Lung Disease (IUATLD) study of drug resistance demonstrated a significant increase in drug-resistant TB among the
foreign-born compared to the locally-born population in many industrialized countries, including Canada(23).

Immigrants and refugees with latent M. tuberculosis infection are at highest risk of developing TB disease within the first 5 years of their arrival(4,11,24). Of foreign-born TB cases in Canada reported in 1998, 8% were diagnosed and reported to have TB disease the same year of arrival, 18% within 2 years and 37% within 5 years(13). The risk of developing TB disease may persist for many years after arrival(25,26).

Transmission of M. tuberculosis from the foreign-born to the locally-born population has been proven through DNA fingerprinting, but has not been demonstrated to make a significant contribution to the number of locally-born TB cases(27-30). Despite the large numbers of immigrants to Canada, the overall incidence of TB disease in all Canadians has not changed since 1987(13). The screening process of immigrants and refugees and followup of those placed on medical surveillance after their arrival in Canada is designed to diagnose and prevent new TB cases in foreign-born individuals and protect other Canadians from this disease(31).

Several Canadian(18,32,33), American(34) and Australian(35) studies have confirmed that the medical surveillance process selects the people at an increased risk of developing active TB disease. This underscores the importance of ensuring that new immigrants and refugees placed under medical surveillance are appropriately investigated and followed up according to these revised guidelines.

Part II
Immigration process leading to referral for medical surveillance

All immigrant applicants, refugees and certain visitors to Canada are required to undergo an immigration medical examination (IME) to identify those who may pose a risk to public health, risk to public safety, or may place excessive demands on Canadian health and social services.

Two types of visitors require medical examinations:

  • visitors who have lived in a designated country for >= 6 consecutive months in the year preceding the date of seeking entry to Canada, and who are intending to stay in Canada for at least 6 months; and

  • visitors intending to work in an occupation where protection of public health is essential (e.g., teachers and physicians), regardless of their country of origin or anticipated length of stay in Canada.

Health Canada uses the WHO estimated TB incidence rates to determine a list of designated countries.

The IME consists of an applicant's medical history, physical examination, and three age-related routine tests: urinalysis (for applicants >= 5 years), chest radiograph (at >= 11 years), and syphilis serology (at >= 15 years). Additional tests may be requested if there is evidence that a significant condition may be present.

For applicants undergoing IME outside Canada:
Applicants identified as having active TB abroad are denied entry to Canada until they have completed a satisfactory course of treatment and are reassessed. Applicants identified as having inactive TB or a past history of TB are placed under medical surveillance as a condition of entry. Such immigrants or visitors are then required to report, within 30 days of entry, to a public health authority in the province/territory (P/T) of destination.

For applicants undergoing IME in Canada:
In-Canada applicants for immigration or other changes of status (e.g., visitor extension beyond a 6 month stay in Canada), and refugee claimants are required to undergo an IME. Refugees must undergo an IME within 60 days of making their claim. Those who are identified with active TB are reported to the appropriate P/T public health authority and required to undergo appropriate treatment. Individuals identified with inactive TB or a past history of TB are placed under medical surveillance whereby they must report to a public health authority in the P/T of residence.

Persons identified as requiring medical surveillance are required to sign a medical surveillance undertaking form (IMM 535). Upon entry to Canada, port of entry officials review the in-Canada residential address on the IMM 535; reinforce the requirement to report to a P/T public health authority within 30 days (terms and conditions of entry are applied); and provide the entrant with a list of P/T public health authority telephone numbers.

Upon complying with the medical surveillance requirement, the entrant is required to provide evidence of compliance from the provincial/public health reviewing authority to any inland Citizenship and Immigration Canada (CIC) office to have the medical surveillance terms and conditions removed.

Part III
Guidelines for the investigation and follow-up of individuals who were referred for medical surveillance for tuberculosis

Individuals newly arrived in Canada may have been referred for medical surveillance for TB by CIC because of a previous history of TB or an abnormal chest radiograph suggestive of inactive TB. Following their arrival in Canada, these persons are required to report to the local public health authorities to establish whether or not active TB currently exists and to determine the appropriate course of medical care, which may include treatment of latent TB infection (LTBI) (see Figure 1).

Figure 1
Follow-up of persons placed under medical surveillance for tuberculosis (TB)

Figure 1: Follow-up of persons placed under medical surveillance for tuberculosis (TB

All individuals referred for medical surveillance should receive a at least one complete medical evaluation by, or together with, a physician experienced in the diagnosis and management of TB. Documents and radiographs pertaining to the immigration medical examination, accessible through CIC or overseas embassies, may be useful for the in-Canada evaluation and establish the reason for referral. The important components of this initial medical evaluation include the following:

1. A comprehensive history, including:

a. Reason for medical surveillance referral;

b. Demographic information (e.g., date of birth, gender, country of birth, country of last residence);

c. Past history of TB;

If yes,

Clinical data - When did the episode of TB occur? Was it respiratory or non-respiratory? How was it treated? Where was it treated? Was treatment completed?

Investigations - Was the diagnosis of TB laboratory-confirmed? Was there documentation of a bacteriologic response to treatment? Is there a history of drug-resistant TB? If there is a history of respiratory TB, are immigration chest radiographs available? Was there documentation of a radiographic response to treatment? Has stability of radiographic abnormalities been demonstrated?

If no,

Investigations - Is there an abnormal immigration chest radiograph, and/or a positive tuberculin skin test result (what is its size, when and where was it performed)?

d. Family history of TB and/or recent contact with respiratory TB;

If yes, documentation?

e. Personal medical history with a TB-specific symptom inquiry (e.g., cough, weight loss, fatigue, fever, night sweats, hemoptysis), record of co-morbidity including immunodeficiency states, currently prescribed medications, and a history of BCG vaccination(s).

II. Targeted physical examination, guided by the history and available laboratory data.

III. Other investigations:

a. Chest radiograph;

b. Sputum for mycobacterial smear and culture if there is a past history of respiratory TB, evidence of old healed TB on chest radiograph or a positive symptom inquiry. Ideally three sputum samples should be collected. These specimens may be collected using spontaneously produced sputum or by sputum induction or first morning gastric aspirates (under proper respiratory isolation);

c. Tuberculin skin test if no documented result;

d. Additional radiographs as indicated by the history and physical examination results.

Based on the results of this initial medical evaluation, the physician should make a recommendation for follow-up. The duration of follow-up for individuals referred for medical surveillance may last up to 3 to 5 years, depending upon the risk of relapse or reactivation, especially with a drug-resistant strain of TB and whether the patient will accept or tolerate treatment of latent TB infection. It is not uncommon that persons who are under routine medical surveillance present with symptoms of active TB disease outside of the scheduled review appointment(36). Therefore, it is important to ensure that barriers to accessing medical care, should symptoms develop, are minimized.

Follow-up after initial medical assessment:

I. If a diagnosis of active TB is established, treatment with an appropriate regimen of anti-TB drugs as defined by the Canadian Tuberculosis Standards (CTS) should be instituted. The treatment regimen should take into account the possibility of drug-resistant TB being present because this is a relatively common problem in parts of the world from which many patients are emigrating(23).

IIa. If a diagnosis of inactive TB is established and if the individual has had no, or inadequate, treatment in the past, then consideration should be given to treatment of LTBI. Persons who are considered high priority for the treatment of TB infection are listed below in Table 1.

Table 1: Priorities for treatment of persons on medical surveillance with latent tuberculosis infection, regardless of age

  • Chest radiographic abnormalities suggestive of previous active tuberculosis (TB) in someone who denies prior history of TB.

  • Persons with a past history of active TB that was untreated or inadequately treated as defined by the Canadian Tuberculosis Standards.

  • Persons with recent contact with an infectious case of active TB (infected within the past 2 years).

  • Persons with a medical condition which increases their risk of
    progressing to active TB:
    • HIV infection;
    • Organ transplantation;
    • Chronic renal failure;
    • Prolonged corticosteroid or immune suppressive drug therapy;
    • Hematologic malignancies - leukemia, lymphoma;
    • Silicosis;
    • Diabetes mellitus;
    • < 90% of ideal body weight.

Young persons (particularly those <= 5 years of age) infected with TB who have been identified through investigations of their parent(s) or guardian(s) may be at increased risk of progressing to active disease and are likely to tolerate therapy without complications.

Elimination of TB in Canada will depend on the identification of infected individuals and treatment of their LTBI to arrest the progression to active disease. Therefore, it is critical that those involved in the investigation and follow-up of individuals referred for medical surveillance for TB be committed to identifying and treating infected individuals who are at increased risk of developing active TB disease. This includes monitoring of their compliance with the prescribed treatment of LTBI. Non-compliance with prescribed treatment may be problematic for those on medical surveillance(37), and has been significantly associated with the development of TB disease in refugees(38). Cultural and community factors may influence patient compliance(39). Strategies to improve compliance should be utilized as appropriate. Consultation with local public health authorities and/or TB clinics as well as the CTS may provide direction.

For those not completing a course of treatment for LTBI, follow-up should be individualized.

IIb. If a diagnosis of inactive TB is made and the individual has had treatment, then follow-up should be individualized. Consultation with a TB expert is required if infection with multidrug-resistant TB is known or suspected.

III. The risk of developing TB disease in immigrants may persist for >= 1 decade after arrival(25,26). Persons who are discharged from follow-up should be advised to seek medical attention promptly if they develop symptoms suggestive of TB and to advise such medical providers of their history of having been on immigration medical surveillance for TB.

References

1. Guidelines for the investigation of individuals who were placed under surveillance for tuberculosis post-landing in Canada. CCDR 1992;18:153-55.

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3. Fanning AE. Globalization of tuberculosis. CMAJ 1998;158:611-12.

4. Report from the British Thoracic and Tuberculosis Association. Tuberculosis among immigrants related to length of residence in England and Wales. Br Med J 1975;3:698-99.

5. Omerod P. Tuberculosis and immigration. Br J Hosp Med 1996;56:209-12.

6. Stehr-Green JK. Tuberculosis in New Zealand, 1985-90. N Z Med J 1992;105:301-03.

7. Heath TC, Roberts C, Winks M et coll. The epidemiology of tuberculosis in New South Wales 1975-1995: the effects of immigration in a low prevalence population. Int J Tuberc Lung Dis 1998;2:647-54.

8. Raviglione MC, Sudre P, Reider HL et coll. Secular trends of tuberculosis in western Europe. Bull World Health Organ 1993;71:297-306.

9. Sosna J, Shulimzon T, Roznman J et coll. Drug-resistant pulmonary tuberculosis in Israel, a society of immigrants, 1985-1994. Int J Tuberc Lung Dis 1999;3:689-94.

10. CDC. Progress towards the elimination of tuberculosis - United States, 1998. MMWR 1999;48:732-36.

11. McKenna MT, McCray E, Onorato I. The epidemiology of tuberculosis among foreign-born persons in the United States, 1986 to 1993. N Engl J Med 1995;332:1071-76.

12. Recommendations of the Advisory Committee for Elimination of Tuberculosis. Tuberculosis among foreign-born persons entering the United States. MMWR 1990;39(RR-18):1-21.

13. Health Canada. Tuberculosis in Canada, 1998. Minister of Public Works and Government Services Canada, 2001.

14. Enarson D, Ashley MJ, Grzybowski S. Tuberculosis in immigrants to Canada. A study of present-day patterns in relation to immigration trends and birthplace. Am Rev Respir Dis 1979;119:11-8.

15. Citizenship and Immigration Canada. Facts and Figures, 1998. Minister of Public Works and Government Services Canada, 1999.

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18. Wang JS, Allen EA, Enarson DA et coll. Tuberculosis in recent Asian immigrants to British Columbia, Canada: 1982-1985. Tubercle 1991;72:277-83.

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20. Long R, Fanning A, Cowie R et coll. Antituberculosis drug resistance in western Canada (1993 to 1994). Can Respir J 1997;4:71-5.

21. Manns BJ, Fanning EA, Cowie RL. Antituberculosis drug resistance in immigrants to Alberta, Canada, with tuberculosis, 1982-1994. Int J Tuberc Lung Dis 1997;1:225-30.

22. Byrd RB, Fisk DE, Roethe RA et coll. Tuberculosis in Oriental immigrants: a study in military dependents. Chest 1979;76:136-39.

23. Organisation mondial de la Santé. Anti-tuberculosis drug resistance in the world: the WHO/IUATLD Global Project on Anti-tuberculosis Drug Resistance Surveillance, 1994-1999. Genève, Suisse : Programme mondial de lutte contre la tuberculose de l'OMS, 2000; rapport no WHO/CDS/TB/2000.278.

24. Codecasa LR, Porretta AD, Gori A et coll. Tuberculosis among immigrants from developing countries in the province of Milan, 1993-1996. Int J Tuberc Lung Dis 1999;3:589-95.

25. Harding MJ, Pilkington P, Thomas J. Tuberculosis epidemiology in Croydon. Public Health 1995;109:251-57.

26. Zuber PLF, McKenna MT, Binkin NJ et coll. Long-term risk of tuberculosis among foreign-born persons in the United States. JAMA 1997;278:304-07.

27. Chin DP, DeRiemer K, Small PM et coll. Differences in contributing factors to tuberculosis incidence in US-born and foreign-born persons. Am J Respir Crit Care Med 1998;158:1797-1803.

28. Jasmer RM, Ponce DL, Hopewell PC et coll. Tuberculosis in Mexican-born persons in San Francisco: reactivation, acquired infection and transmission. Int J Tuberc Lung Dis 1997;1:536-41.

29. Borgdorff MW, Behr MA, Nagelkerke NJD et coll. Transmission of tuberculosis in San Francisco and its association with immigration and ethnicity. Int J Tuberc Lung Dis 2000;4:287-94.

30. Long R, Chui L, Kakulphimp et coll. The post-sanatorium pattern of antituberculosis drug resistance in the Canadian-born population of western Canada: effect of outpatient care and immigration. Am J Epidemiol 2001;153:903-11.

31. Thomas RE, Gushulak B. Screening and treatment of immigrants and refugees to Canada for tuberculosis: implications of the experience of Canada and other industrialized countries. Can J Infect Dis 1995;6:246-55.

32. Orr PH, Manfreda J, Hershfield ES. Tuberculosis surveillance in immigrants to Manitoba. Can Med Assoc J 1990;142:453-58.

33. Wobeser W, Yuan L, Naus M et coll. Expanding the epidemiologic profile - risk factors for tuberculosis among persons immigrating to Ontario. Can Med Assoc J 2000;163:823-28.

34. Sciortino S, Mohle-Boetani J, Royce SE et coll. B notifications and the detection of tuberculosis among foreign-born recent arrivals in California. Int J Tuberc Lung Dis 1999;3:778-85.

35. Pang SC, Harrison RH, Brearley J et coll. Tuberculosis surveillance in immigrants through health undertakings in Western Australia. Int J Tuberc Lung Dis 2000;4:232-36.

36. Styblo K, van Guens HA, Meijer J. The yield of active case-finding in persons with inactive pulmonary tuberculosis or fibrotic lesions. A 5-year study in tuberculosis clinics in Amsterdam, Rotterdam and Utrecht. Tubercle 1984;65:237-51.

37. Pang SC, Harrison RH, Brearley J et coll. Preventive therapy for tuberculosis in Western Australia. Int J Tuberc Lung Dis 1998;2:984-88.

38. MacIntyre CR, Ansari MZ, Carnie J et coll. No evidence for multiple-drug prophylaxis for tuberculosis compared with isoniazid alone in Southeast Asian refugees and migrants: completion and compliance are major determinants of effectiveness. Prev Med 2000;30:425-32.

37. Pang SC, Harrison RH, Brearley J et al. Preventive therapy for tuberculosis in Western Australia. Int J Tuberc Lung Dis 1998;2:984-88.

38. MacIntyre CR, Ansari MZ, Carnie J et al. No evidence for multiple-drug prophylaxis for tuberculosis compared with isoniazid alone in Southeast Asian refugees and migrants: completion and compliance are major determinants of effectiveness. Prev-Med 2000;30:425-32.

39. Ito KL. Health culture and the clinical encounter: Vietnamese refugees' responses to preventive drug treatment of inactive tuberculosis. Med Anthropolol Q 1999;13:338-64.

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