Chapter 13 of the Canadian Tuberculosis Standards: Tuberculosis surveillance and tuberculosis infection testing and treatment in migrants

Authors and affiliations

Christina Greenaway; Department of Medicine, McGill University, Montréal, Québec, Canada; Division of Infectious Diseases, SMBD-Jewish General Hospital, Montréal, Québec, Canada; McGill International TB Centre, Montréal, Québec, Canada; Centre for Clinical Epidemiology, Lady Davis Institute, Jewish General Hospital, Montréal, Québec, Canada

Tanya Diefenbach-Elstob; Department of Medicine, McGill University, Montréal, Québec, Canada; Centre for Clinical Epidemiology, Lady Davis Institute, Jewish General Hospital, Montréal, Québec, Canada

Kevin Schwartzman; Department of Medicine, McGill University, Montréal, Québec, Canada; McGill International TB Centre, Montréal, Québec, Canada; Montréal Chest Institute, Montréal, Québec, Canada; Research Institute of the McGill University Health Centre, Montréal, Québec, Canada

Victoria J. Cook; British Columbia Centre for Disease Control, Vancouver, British Columbia, Canada; Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada

George Giovinazzo; Migration Health Branch, Immigration, Refugees and Citizenship Canada, Government of Canada, Ottawa, Ontario, Canada

Howard Njoo; Infectious Disease Prevention and Control Branch, Public Health Agency of Canada, Ottawa, Ontario, Canada

Aboubakar Mounchili; Antimicrobial Resistance Division, Public Health Agency of Canada, Ottawa, Ontario, Canada

James Brooks; Antimicrobial Resistance Division, Public Health Agency of Canada, Ottawa, Ontario, Canada

Key points

All foreign-born persons immigrating to Canada and certain temporary residents undergo a mandatory medical immigration examination before arrival. This examination includes a chest x-ray for all applicants ≥11 years of age. Those found to have active pulmonary or laryngeal tuberculosis (TB) must be treated prior to arrival to ensure they are no longer infectious.
Immigration, Refugees and Citizenship Canada requires individuals found during their immigration medical examination to have previously treated TB, inactive pulmonary TB, extra-pulmonary TB, recent household/close contact with a person with active TB or TB infection with a high risk of reactivation to undergo subsequent provincial/ territorial TB surveillance within a specified timeframe following arrival.
Only a small proportion (<3%) of all active TB diagnoses among the foreign-born population made after arrival in Canada are identified during the immigration post-landing surveillance program. This underscores the need for additional approaches to identify foreign-born persons with TB infection who are at increased risk of TB reactivation after arrival.
The selection of people for targeted TB infection testing and treatment should be considered in the context of their prior and/or ongoing risk of TB exposure and their risk of reactivation, including demographic and medical risk factors, balanced against the likelihood of safe completion of TB preventive treatment, including the risk of adverse events.
There is substantial attrition of individuals throughout the TB infection testing and treatment cascade. Improvements in the implementation, uptake and completion of TB infection testing and treatment will require investment in TB education programs for patients and providers, as well as addressing setting-specific barriers to care to ensure the delivery of culturally-sensitive TB prevention and care.

1. Overview of TB among migrants

Canada is a leading destination for migrants, both in numbers received and on a per-population basis, receiving on average more than 250,000 immigrants and refugees each year. As a result, there are now approximately 7.5 million foreign-born persons living in Canada, accounting for 21.9% of the population.^{Footnote 1} Over the past 50 years, there has been a major demographic shift in the source countries of new migrants to Canada. Before the 1970s, most individuals immigrating to Canada originated from Western European countries. Since that time, the proportion of immigrants originating from intermediate or high TB-incidence countries such as in Asia, Africa and Latin America has increased. In the 2016 census, an estimated 68% of migrants to Canada originated from countries with an intermediate or high TB incidence.^{Footnote 1}

The two main administrative classifications of migrants arriving in Canada are 1) permanent residents who come to Canada to resettle; and 2) temporary residents who are visiting, studying or working in Canada on a time-limited basis. Permanent and temporary residents are further classified into several subgroups based on their immigration status (see Table 1). In addition, Canada receives millions of international visitors each year; in 2019, 32 million nonresident travelers arrived in Canada.^{Footnote 2} Most immigrant groups apply for permission to come to Canada while still living in their countries of origin, although asylum seeker claimants who apply upon or after arrival in Canada are an important exception. As well, there are a substantial number of undocumented migrants living in Canada, estimated to be anywhere from 20,000 to 500,000 persons.^{Footnote 3}

Table 1. Classification of international migration to Canada (arrivals in 2019)
Immigration category	Number of persons^{Footnote a}
Permanent residents^{Footnote b}
Economic class	197,000
Family reunification	91,000
Humanitarian and compassionate	5,000
Refugees and protected persons	49,000
Total	342,000
Temporary residents^{Footnote b}
International students	402,000
Foreign workers (Temporary Foreign Worker program and International Mobility Program)	405,000
Total	807,000
Non-residents: visitors or travelers	32,000,000
Notes: Data from Government of Canada – Immigration, Refugees and Citizenship Canada and Statistics Canada.^{Footnote 2}^{Footnote 4} Footnotes: Footnote a Numbers rounded to nearest 1,000. Return to footnote a referrer Footnote b For permanent residents, the number of persons admitted. For temporary residents, the number of new work/study permits issued. Return to footnote b referrer

Tuberculosis in Canada has increasingly become concentrated in specific population groups such as the foreign-born, Indigenous populations, and people with medical, social and/or behavioral risk factors, such as human immunodeficiency virus (HIV) infection, homelessness and injection drug use.^{Footnote 5} In 2019, foreign-born persons accounted for 74.2% of all active TB diagnoses in Canada, and had an overall 40-fold higher incidence of TB than the non-Indigenous, Canadian-born population (15.8 vs 0.4 cases/100,000 population), although rates are much higher in certain subgroups of immigrants.^{Footnote 6} Among foreign-born TB patients with a known immigration status at the time of diagnosis, approximately three-quarters of diagnoses occurred among citizens and permanent residents, and 15% occurred among temporary residents (i.e., students, foreign workers and visitors).^{Footnote 6} Most TB in the foreign-born population in Canada occurs as a result of reactivation of TB infection that was acquired in their country of origin. TB infection prevalence increases depending on the country of origin, with interferon-gamma release assay (IGRA) positivity ranging from 2.9% (95% CI 0.2-31.7) for foreign-born persons from countries with TB incidence <30 cases per 100,000 people to 36% (95% CI 26.3-41.7) for those from countries with ≥200 cases per 100,000 people (range 19.9-41.6% for tuberculin skin test (TST) positivity).^{Footnote 7}^{Footnote 8}

2. TB-related immigration screening requirements

2.1. Pre-entry examination and TB screening

Immigration, Refugees and Citizenship Canada requires all individuals applying for permanent residency and certain individuals applying for temporary residency to undergo an immigration medical exam. This exam includes screening for active TB with a chest radiograph in all persons ≥11 years of age, and testing for TB infection in certain high-risk groups (see Table 2).^{Footnote 9}^{Footnote 10} For temporary residents, the requirement for an exam is dependent on the intended duration of stay in Canada, type of employment and duration of residency in TB-endemic countries.^{Footnote 12} The objective of pre-entry TB screening is to detect prevalent active pulmonary TB in migrants prior to arrival to ensure that they are treated and no longer infectious when they enter Canada.^{Footnote 9} TB infection screening in certain groups at high risk for reactivation was added in May 2019 (see Table 2).

Table 2. Required pre-arrival screening for active TB and TB infection

All persons applying for permanent resident status and selected nonpermanent residents undergo the following screening for TB during the immigration medical exam:^{Footnote 13}

All applicants ≥11 years of age: a chest radiograph
Applicants <11 years who are in a defined TB high risk group (see below): a chest radiograph
All individuals in a TB high-risk group (see below):
- If ≥2 years of age: IGRA testing (or TST if IGRA unavailable)
- If <2 years of age: TST
The TB high-risk group refers to the following individuals (as of May 2019):
- Close contact with an active TB case in the previous 5 years
- HIV-positive serology
- History of certain head and neck cancers within the previous 5 years
- Dialysis or advanced CKD (eGFR <30 mL/min/1.73 m²)
- Solid organ or bone marrow transplant and on immunosuppressant therapy

If active pulmonary TB is diagnosed it must be treated in accordance with recognized guidelines (such as the Canadian TB Standards).^{Footnote 13} Before being given permission to enter Canada, applicants must submit proof of successful treatment completion, 3 negative sputum smears and cultures and stable and/or improving chest radiographs. Persons at high risk of progression to active disease found to have a positive test for TB infection (TST ≥5mm or positive IGRA) must be referred for post-landing provincial/territorial TB medical surveillance.^{Footnote 13} In 2019, 885 cases of active TB (0.10%) were identified in 893,000 immigration medical assessments (i.e., 0.03% of 258,000 immigration medical exams done in Canada and 0.13% of 635,000 immigration medical exams done overseas).^{Footnote 14}

2.2. Post-landing surveillance

The primary purpose of the post-landing medical surveillance program in Canada is to follow persons identified during the pre-landing exam to be at high risk of developing active pulmonary TB, and thus to prevent subsequent TB disease and transmission in Canada. Approximately 2-2.5% of those who undergo pre-arrival TB screening are targeted for medical surveillance (Table 3).^{Footnote 15}^{Footnote 16} Referred persons must report to, or be contacted by, a public health authority within 30 days of landing for inactive TB or within 7 days of landing for urgent cases of inactive TB or extra-pulmonary TB.^{Footnote 17}

Table 3. Criteria for referral following the immigration medical examination to post-landing medical surveillance^{Footnote 17}^{Footnote 18}

Previously treated TB
Inactive pulmonary TB on chest x-ray (after investigations to exclude active pulmonary TB)
Extra-pulmonary tuberculosis
Household/close contacts of persons with active TB within the previous five years
Individuals with a reactive pre-landing IGRA or TST who are at high risk for TB reactivation (e.g., CKD, HIV, history of certain head and neck cancer in previous 5 years, solid organ or bone marrow transplant recipients who are on immunosuppressive therapy)

Implementation of post-landing surveillance varies among the provinces and territories, some having a centralized process and others having a decentralized or hybrid system. Provincial or territorial public health authorities must contact referred immigrants to facilitate medical surveillance and follow-up and, subsequently, must inform Immigration, Refugees and Citizenship Canada of compliance with medical surveillance. Most migrants are responsible for their own healthcare funding until they are eligible for provincial/ territorial health insurance, which may be up to three months after arrival. Compliance, defined as keeping the first appointment for a clinical assessment, is low (49%) and has been shown to improve by addressing language barriers, eliminating waiting periods for provincial/territorial health insurance, improving clinic capacity through prescreening, centralization, extended clinic hours and facilitating appointments with incentives or enablers.^{Footnote 19}^{Footnote 20} The post-landing surveillance program is limited by the fact that only a minority of those referred (0.8-2.8%) are identified as having active TB.^{Footnote 15}^{Footnote 16}^{Footnote 21} Additional efforts must therefore be invested in identifying and treating TB infection in non-referred migrants after arrival in Canada, as outlined in the following section.^{Footnote 15}^{Footnote 20}^{Footnote 22}

2.3. Non-mandated post-arrival TB infection testing for immigrants

Despite the high prevalence of TB infection among foreign-born persons in Canada (see chapter overview), there are no routine post-arrival domestic TB infection testing and treatment programs. Risk factors associated with the highest rates of active TB among foreign-born populations include:^{Footnote 15}^{Footnote 23}^{Footnote 24}^{Footnote 25}^{Footnote 26}^{Footnote 27}^{Footnote 28}^{Footnote 29}^{Footnote 30}^{Footnote 31}^{Footnote 32}^{Footnote 33}^{Footnote 34}^{Footnote 35}^{Footnote 36}^{Footnote 37}^{Footnote 38}^{Footnote 39}^{Footnote 40}

The global country or region of origin, especially sub-Saharan Africa, Asia and the Western Pacific regions (see Chapter 1: Epidemiology of tuberculosis in Canada)
Immigration category (refugees have roughly double the risk compared to other immigrants after arrival in host country)^{Footnote 28}
Time since arrival in the host country (5 to 10 times higher in the first year and 2 times greater 1 to 4 years after arrival, as compared to 5 years or longer after arrival)^{Footnote 30}^{Footnote 32}^{Footnote 34}
Underlying medical co-morbidities (see Chapter 4: Diagnosis of tuberculosis infection)

Most TB cases among foreign-born persons occur due to reactivation of previously acquired TB infection. However, based on evidence from studies of genetic clustering, 10-30% of cases may be due to infection acquired after arrival.^{Footnote 41}^{Footnote 42}^{Footnote 43}^{Footnote 44}^{Footnote 45} The possibility of transmission within Canada should therefore be considered in the assessment of foreign-born TB patients, their family members (including those born in Canada) and other contacts, given the need for prompt diagnosis to limit the risk of onward transmission (see Chapter 11: Tuberculosis contact investigation and outbreak management).^{Footnote 46} Current diagnostic tools for TB infection (IGRA and TST) do not sufficiently predict the likely occurrence or timing of reactivation.^{Footnote 47} Only 5-10% of persons with TB infection will develop active TB, with 50% of this risk occurring (or having already occurred) within the first two years after infection.^{Footnote 48} Shorter course rifamycin treatments are the preferred tuberculosis preventive treatment (TPT) regimens (see Chapter 6: Tuberculosis preventive treatment in adults). Serious adverse events occur in <1% of those less than 65 years of age who take 4 months of rifampin; the rate increases in persons over 65 years of age and those with underlying medical co-morbidities.^{Footnote 49}^{Footnote 50}^{Footnote 51}^{Footnote 52}

2.3.1. Targeted testing and treatment for TB infection among the foreign-born population in Canada

The probability that persons being considered for TB infection testing will have a positive test for TB infection and will develop active TB depends on the likelihood of TB exposure, the timing of exposure and the presence of risk factors for developing active TB. The decision to offer TB infection testing should consider the balance of benefits and risks to the patient. Only those who will benefit from treatment should be tested, so a decision to test presupposes a decision to treat if the test is positive. To make recommendations for TB infection testing among migrants, we chose a threshold of risk of developing active TB of 1% within 5 years among those with a positive test. We recognize that patients may have different values and preferences when considering the level of risk that may prompt a decision to initiate treatment. We estimated the risk of developing TB in different groups of immigrants based on age, TB incidence in the country of birth, time since arrival, immigration status (e.g., refugees) and underlying medical co-morbidities, using a large cohort of immigrants who arrived in British Columbia between 1985 and 2012 who were followed for a median of 10 years.^{Footnote 28}^{Footnote 53} The immigrant groups that met the 1% threshold included those with underlying medical conditions with a high risk of TB reactivation and certain groups of refugees and recently arrived foreign-born persons with specified TB incidence in source country, age and time-since-arrival. Individualized TB infection testing may be considered for persons who do not belong to the groups listed below for whom this is recommended, after discussing the risk of reactivation and adverse events with the patient.

Recommendations:

We strongly recommend TB infection testing in all people (all ages) born outside of Canada with conditions associated with a very high risk of TB reactivation (good evidence).
- See Table 2, Chapter 4: Diagnosis of tuberculosis infection.
We conditionally recommend TB infection testing in all foreign-born persons (all ages) originating from countries with a TB incidence ≥50/100,000 and with conditions associated with a high risk of TB reactivation (poor evidence).
- See Table 2, Chapter 4: Diagnosis of tuberculosis infection.
- For TB incidence in individual countries see the World Health Organization TB country, regional and global profiles online tool.^{Footnote 54}
We conditionally recommend TB infection testing in refugees originating from countries with TB incidence ≥50/100,000 who are aged ≤65 years as soon as possible after arrival and up to two years after arrival. Testing for those aged >65 years can be considered in the context of their individual reactivation risk profile and risk of adverse events (poor evidence).
- For TB incidence in individual countries see the World Health Organization TB country, regional and global profiles online tool.^{Footnote 54}
We conditionally recommend that TB infection testing may be considered for persons born outside Canada, originating from countries with a TB incidence >200/100,000, who have low to moderate risk of TB reactivation and are aged ≤65 years as soon as possible and within five years of arrival. Screening for those aged >65 years can be considered in the context of their individual reactivation risk profile and risk of adverse events. At the individual provider-patient level, providers should discuss and emphasize the benefits vs risks of TB infection testing and treatment (poor evidence).
- For TB incidence in individual countries see the World Health Organization TB country, regional and global profiles online tool.^{Footnote 54}
We conditionally recommend against routine TB infection testing for people born outside Canada who have come from countries with a TB incidence of <50/100,000 and who have no risk factors for reactivation (poor evidence).
- For TB incidence in individual countries see the World Health Organization TB country, regional and global profiles online tool.^{Footnote 54}

2.4. Important considerations in TB infection testing and treatment among the foreign-born population

2.4.1. TB infection care cascade

TB infection testing and treatment involves numerous steps (known as the care cascade), including testing, receiving a result, referral if test positive, recommendation for treatment and treatment initiation and completion.^{Footnote 55} Loss of individuals can occur at any step along the care cascade, and many TB infection testing and treatment programs among immigrants perform poorly due to losses throughout the care cascade.^{Footnote 55}^{Footnote 56}^{Footnote 57}^{Footnote 58}^{Footnote 59} In two systematic reviews and meta-analyses of studies of TB infection testing and treatment in immigrants after arrival, 55-69% of migrants who tested positive for TB infection initiated treatment; 73-74% of those who started treatment completed it, with higher initiation and completion in more recent years.^{Footnote 55}^{Footnote 56} The overall TB infection care cascade among immigrants is weak; one review of the final steps of the care cascade found that only 52% of migrants receiving a medical evaluation initiated and completed treatment. Another review of the entire cascade found that only 14% of all migrants estimated to be positive for TB infection completed treatment.^{Footnote 55}^{Footnote 56} For a strong cascade, physicians/providers need to be educated to test patients, offer treatment and encourage treatment completion, and patients need to accept and complete testing and treatment when offered.

2.4.2. Barriers to accessing TB infection testing and treatment

Immigrants and refugees may encounter significant barriers at the patient, provider and system levels when accessing TB infection testing and treatment. General barriers to accessing primary healthcare among immigrant populations in Canada have been summarized in a systematic review.^{Footnote 60} Several barriers mentioned in that review are relevant to TB, including cultural barriers, communication barriers (such as language discordance), socioeconomic factors (financial and work-related), concerns about confidentiality and lack of patient knowledge or trust involving the Canadian healthcare system.^{Footnote 60} There are also structural barriers, especially related to a lack of interpreter services in many healthcare settings, that can result in patient-provider miscommunication and compromise the quality of healthcare delivery and patient safety.^{Footnote 61} Key additional patient, provider and system-level barriers are detailed in Table 4.

Table 4. Barriers for TB infection testing and treatment
Barriers	References
Patient-level
Fear of stigma and/or discrimination	^{Footnote 62}^{Footnote 63}^{Footnote 64}^{Footnote 65}^{Footnote 66}^{Footnote 67}
Concerns of unfair targeting, racism, perpetuation of stereotypes	^{Footnote 62}^{Footnote 65}^{Footnote 68}
Privacy and confidentiality issues	^{Footnote 62}^{Footnote 64}
Language barriers	^{Footnote 64}^{Footnote 66}^{Footnote 69}^{Footnote 70}^{Footnote 71}
Competing priorities	^{Footnote 68}^{Footnote 71}
Low level of education	^{Footnote 72}^{Footnote 73}
Economic factors (travel and other costs, missed work opportunities, precarious employment)	^{Footnote 62}^{Footnote 63}^{Footnote 65}^{Footnote 71}^{Footnote 74}^{Footnote 75}^{Footnote 76}
Difficulties navigating and interacting with the healthcare system	^{Footnote 63}^{Footnote 64}^{Footnote 66}^{Footnote 69}^{Footnote 76}^{Footnote 77}
Lack of family support	^{Footnote 73}
Long treatment duration and side effects	^{Footnote 63}^{Footnote 71}^{Footnote 74}^{Footnote 75}^{Footnote 78}^{Footnote 79}
Reluctance to undergo venipuncture	^{Footnote 69}^{Footnote 80}
Lack of knowledge and/or confusion about TB infection, impact of prior BCG and TST	^{Footnote 63}^{Footnote 64}^{Footnote 65}^{Footnote 66}^{Footnote 68}^{Footnote 70}^{Footnote 71}^{Footnote 75}^{Footnote 76}^{Footnote 81}^{Footnote 82}^{Footnote 83}
Perception of low risk of progression to active TB	^{Footnote 62}^{Footnote 63}^{Footnote 80}
Provider-level
Lack of knowledge/experience in TB infection screening and treatment procedures	^{Footnote 75}^{Footnote 78}^{Footnote 84}^{Footnote 85}
Non-adherence to screening guidelines and low prioritization of TB infection	^{Footnote 75}^{Footnote 78}^{Footnote 86}^{Footnote 87}^{Footnote 88}
Resource limitations (e.g., need for more/longer appointments, extra and/or specialized staff)	^{Footnote 84}
Concerns about potential re-infection during patient travel	^{Footnote 74}^{Footnote 75}
Structural-level
Lack of interpreters	^{Footnote 69}^{Footnote 70}
Abbreviations: BCG, Bacillus Calmette-Guérin; TST, tuberculin skin test.

2.4.3. Strategies to improve TB infection testing and treatment uptake and completion

Strategies are needed to improve TB infection testing and treatment uptake and completion among at-risk foreign-born persons. Such strategies should focus on addressing context-specific barriers such as those described in the previous section (see Table 4). Facilitators of testing and treatment implementation and completion at the patient and provider level are detailed in Table 5. Engagement with community members and community-based organizations and offering services in diverse settings such as integrated care in a primary care setting or community centers have been successful. Language-concordant encounters between immigrants and health care workers, use of cultural case managers and community engagement and education are key to successful programs.^{Footnote 68}^{Footnote 89}^{Footnote 90}^{Footnote 91}^{Footnote 92} Programs that take a syndemics approach and provide integrated multi-disease screening of high-prevalence conditions such as TB infection, viral hepatitis and HIV have been acceptable to migrants and have led to increased detection of infections, including TB infection.^{Footnote 88}^{Footnote 93}^{Footnote 94}^{Footnote 95}^{Footnote 96} Several interventions have been found to improve completion of steps along the TB infection care cascade, including patient incentives, health care worker education, home visits, digital aids and patient reminders.^{Footnote 97} Educating primary care providers to identify, promote and deliver testing and treatment services among migrants at risk have been shown to increase screening uptake and diagnosis of active TB disease and TB infection.^{Footnote 84}^{Footnote 98}^{Footnote 99}

Table 5. Facilitators and strategies to improve TB infection testing and treatment uptake and completion
Facilitators and strategies to improve uptake	References
Addressing language barriers (e.g., with interpreters)	^{Footnote 62}^{Footnote 69}^{Footnote 70}^{Footnote 89}^{Footnote 90}
Engaging with local communities (e.g., collaboration with community leaders, community-based organizations and members, community health workers and other support workers) in delivering TB services	^{Footnote 62}^{Footnote 64}^{Footnote 68}^{Footnote 77}^{Footnote 91}^{Footnote 100}^{Footnote 101}^{Footnote 102}
Ensuring consistent care and sensitive/supportive patient-provider relationships	^{Footnote 64}^{Footnote 69}^{Footnote 70}^{Footnote 92}
Providing patient education and awareness raising, and providing culturally sensitive materials and care	^{Footnote 63}^{Footnote 64}^{Footnote 68}^{Footnote 69}^{Footnote 81}^{Footnote 92}
Family Support	^{Footnote 103}
Education, training and support of screening providers	^{Footnote 81}^{Footnote 84}^{Footnote 97}^{Footnote 98}^{Footnote 99}
Improved provider resources and funding	^{Footnote 84}
Reminder systems	^{Footnote 97}^{Footnote 99}
Expanded screening approaches (e.g., additional reviews, clinics run by alternative providers, offering services in diverse settings)	^{Footnote 78}^{Footnote 82}^{Footnote 104}
Multi-disease screening programs	^{Footnote 88}^{Footnote 93}^{Footnote 94}^{Footnote 95}
Shorter treatment regimens	^{Footnote 50}^{Footnote 57}^{Footnote 73}^{Footnote 79}^{Footnote 105}^{Footnote 106}^{Footnote 107}

Good practice statements:

TB infection testing and treatment programs should aim to provide linguistically tailored, culturally sensitive and trauma-informed care that is sensitive to the barriers patients may face in accessing care and completing testing and treatment requirements.
Programs able to assure a high level of provider and patient adherence and support are best placed to initiate TB infection testing and treatment activities; any such programs should carefully document both costs and clinical outcomes.

2.4.4. Travel-associated TB

Travel to TB-endemic countries poses a risk for TB infection, which is of relevance for foreign-born populations returning to their countries of birth to visit friends and relatives (VFR travelers). However, the magnitude of TB risk in this group is not precisely known. Travel-associated TB infection and active TB risk among health care workers, military personnel and general travelers/volunteers was estimated in a recent systematic review.^{Footnote 108} Among these 3 groups, the cumulative incidences of TB infection for travel durations up to 6 months were estimated at 4.3% (95% CI 2.8-6.7), 2.5% (95% CI 2.0-2.9) and 1.6% (95% CI 1.0-2.5), respectively, with health care workers having the greatest risk.^{Footnote 108} The incidence of active TB was estimated to be 120.7 cases per 100,000 travelers for all studies in the analysis reporting active TB associated with travel (i.e., travel durations up to 24 months).^{Footnote 108}

Determining the risk of TB among migrants due to travel is a challenge, as only a minority (20-30%) seek pre-travel advice and there are no prospective pre-/post-travel screening studies that estimate this risk.^{Footnote 109}^{Footnote 110}^{Footnote 111} Several small observational studies suggest that VFR travel is associated with increased risk of TB and report that 15-50% of active TB cases in some foreign-born populations are due to recent return travel to their countries of origin.^{Footnote 112}^{Footnote 113}^{Footnote 114}^{Footnote 115}^{Footnote 116} This is supported by a study of ill travelers presenting to 16 European clinics (EuroTravNet) in the GeoSentinel network between 2008-2010, which found that VFR travelers had a more than 15-fold higher risk (3.67% [91/2477] vs 0.23% [33/14,140] vs 0.24% [4/1,686]) of being diagnosed with active TB after travel as compared to other short-term travelers or expatriate travelers respectively.^{Footnote 112} The risk of TB among immigrants who travel also increases with trip duration. In a case-control study in the Netherlands, the travel-associated odds ratio (OR) for active TB among Moroccan immigrants with less than three months of trave to Morocco was 3.2 (95% CI 1.3–7.7), and increased to 17.2 (95% CI 3.7–79) when the cumulative duration of travel exceeded three months.^{Footnote 116} Health care practitioners should also consider the possibility of TB infection among VFR children and Canadian-born children who travel to the country of origin of their foreign-born parents. In two studies in the United States, the OR for a positive TST after travel to a TB-endemic country was 1.9 among Mexican-American children and 1.8 in a mixed cohort of children living in New York City, 78% of whom were Hispanic.^{Footnote 117}^{Footnote 118}

The optimal strategy to test for TB infection among VFR travelers is still to be determined. A cost-effectiveness analysis of TB infection testing among moderate and high TB-incidence countries found that the most effective (preventing the most active TB cases) and cost-effective strategy for detecting travel-associated TB infection was a single post-trip TST. Testing became more cost-effective as trip duration and the TB incidence of the country visited increased, but was reduced if there was poor treatment adherence.^{Footnote 119} New TB infection should be considered among foreign-born persons who have recently traveled to an intermediate or high TB-incidence country based on their duration of travel and the TB incidence in the country visited. Those who have engaged in healthcare work are at the highest risk for TB infection.

Recommendation:

We conditionally recommend that the risks and benefits of TB infection testing and treatment be discussed with particular attention to travelers visiting friends and relatives (including Canadian-born children of foreign-born parents); people engaging in higher-risk travel such as travel for healthcare work; and/or persons born in low TB-incidence countries who have lived in moderate or high TB-incidence countries for prolonged periods of time. The following should be considered high risk when counseling travelers to moderate or high TB-incidence countries:
- Any travel with very high-risk contact, particularly direct patient contact in a hospital or indoor setting, and also potentially work in prisons, homeless shelters, refugee camps or inner-city slums.
- ≥3 months of travel to TB-incidence country ≥400/100,000 population
  - For TB incidence in individual countries see the World Health Organization TB country, regional and global profiles online tool.^{Footnote 54}
- ≥6 months of travel to TB-incidence country 200-399/100,000 population
  - For TB incidence in individual countries see the World Health Organization TB country, regional and global profiles online tool.^{Footnote 54}
- ≥12 months of travel to TB-incidence country 100-199/100,000 population
  - For TB incidence in individual countries see the World Health Organization TB country, regional and global profiles online tool.^{Footnote 54}
(poor evidence)

2.4.5. Limitations of migrant testing and treatment for TB infection

Several studies have assessed the effectiveness and cost-effectiveness of TB infection testing and treatment among migrants in the pre-arrival, post-landing surveillance and post-arrival settings.^{Footnote 22}^{Footnote 53}^{Footnote 119}^{Footnote 120}^{Footnote 121}^{Footnote 122}^{Footnote 123} On the one hand, widely applied post-arrival TB infection testing and treatment among immigrants is not a cost-effective strategy and could have an enormous impact on primary-care infrastructure as well as on healthcare budgets.^{Footnote 121} On the other hand, narrowly focusing TB infection testing only on those with medical risk factors who have a high risk of developing active TB disease, such as persons with HIV infection, close TB contacts, or using tumor necrosis factor antagonists would only detect infection in a tiny minority of the migrant population, who account for a small proportion of TB disease. Among more than a million migrants who took up permanent residence in British Columbia between 1985 and 2012, only 1.5% had or developed such risk factors and this strategy would require testing 136 persons to prevent 1 case and only prevent 4.2% of all TB cases in this cohort.^{Footnote 53} Targeted testing based on TB disease incidence in migrants' source countries, age and presence of underlying medical co-morbidities is the approach taken in this chapter and is supported by some data. In the same BC cohort of immigrants, TB infection testing of all migrants with high-risk medical co-morbidities as well as those aged less than 65 years from countries with annual TB incidence >200 per 100,000 would require testing ~30% of the population (about 10,000 annually), amounting to testing 204 persons to prevent 1 case of TB, and would prevent 50% of potentially preventable TB disease in the cohort.^{Footnote 53}

3. Conclusions

Canada is home to a large number of foreign-born people, accounting for more than 20% of the total population. Canada has a low incidence of TB, but about 70% of TB diagnoses occur among foreign-born persons. Only a minority of active TB cases among the foreign-born population are identified during post-landing surveillance programs; as a result, additional TB preventive strategies are required. The recommended approach is targeted TB infection testing and treatment that balances risks and benefits: considering the risk of prior TB exposure and of progression to active disease vs. the risk of adverse effects and the likelihood of treatment completion. Post-arrival TB infection testing and treatment are limited by substantial attrition in the care cascade. The impact of TB infection testing and treatment will be optimized among the foreign-born population if programs address patient and provider barriers and are linguistically- and culturally-sensitive.

Disclosure statement

The Canadian Thoracic Society (CTS) TB Standards editors and authors declared potential conflicts of interest at the time of appointment and these were updated throughout the process in accordance with the CTS Conflict of Interest Disclosure Policy. Individual member conflict of interest statements are posted on the CTS website.

Funding

The 8th edition Canadian Tuberculosis Standards are jointly funded by the CTS and the Public Health Agency of Canada, edited by the CTS and published by the CTS in collaboration with the Association of Medical Microbiology and Infectious Disease (AMMI) Canada. However, it is important to note that the clinical recommendations in the Standards are those of the CTS. The CTS TB Standards editors and authors are accountable to the CTS Respiratory Guidelines Committee (CRGC) and the CTS Board of Directors. The CTS TB Standards editors and authors are functionally and editorially independent from any funding sources and did not receive any direct funding from external sources. The CTS receives unrestricted grants which are combined into a central operating account to facilitate the knowledge translation activities of the CTS Assemblies and its guideline and standards panels. No corporate funders played any role in the collection, review, analysis or interpretation of the scientific literature or in any decisions regarding the recommendations presented in this document.

References

Footnote 1

Statistics Canada. Immigration and ethnocultural diversity: key results from the 2016 census. Statistics Canada; 2017. https://www150.statcan.gc.ca/n1/daily-quotidien/171025/dq171025b-eng.htm Accessed June 14, 2021.

Return to footnote 1 referrer

Footnote 2

Statistics Canada. Table 24-10-0005-01 International travellers entering or returning to Canada, by province of entry, seasonally adjusted. Accessed May 25, 2021. doi:10.25318/2410000501-eng.

Return to footnote 2 referrer

Footnote 3

Magalhaes L, Carrasco C, Gastaldo D. Undocumented migrants in Canada: a scope literature review on health, access to services, and working conditions. J Immigr Minor Health. 2010;12(1):132–151. doi:10.1007/s10903-009-9280-5.

Return to footnote 3 referrer

Footnote 4

Immigration, Refugees and Citizenship Canada. 2020 annual report to Parliament on immigration. Immigration, Refugees and Citizenship Canada; 2020. https://www.canada.ca/en/immigration-refugees-citizenship/corporate/publications-manuals/annual-report-parliament-immigration-2020.html. Accessed June 28, 2021.

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Footnote 5

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Jo Y, Shrestha S, Gomes I, et al. Model-based cost-effectiveness of state-level latent tuberculosis interventions in California, Florida, New York, and Texas. Clin Infect Dis. 2021;73(9):e3476–e82. doi:10.1093/cid/ciaa857.

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Date modified:: 2025-03-13

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