Piecing the puzzle together: foreign-born tuberculosis in an immigrant-receiving country

In major immigrant-receiving countries, annual foreign-born tuberculosis (TB) case counts and rates are relatively constant. Why this is so, and who might be a high-yield target for screening for latent TB infection, remain open questions. Foreign-born TB in Canada during 1986-2002 was retrospectively examined using national TB and immigration data as well as census data. Case counts and rates were analysed in relation to demographics, immigration period and time since arrival. Pre-1986 immigrants (n=3,860,853) and 1986-2002 immigrants (n=3,463,283) contributed 8,662 and 9,613 TB cases, respectively. Immigrants arriving ≤ 5 yrs ago and those arriving >10 yrs ago contributed almost equally to the annual foreign-born TB case count despite a 3.5-fold difference in in-country person-yrs. Remarkably stable and relatively low TB incidence was observed among immigrants >10 yrs post-arrival. Conversely, TB incidence within 5 yrs of arrival was dynamic, demonstrating a strong inverse association with time since arrival and higher sensitivity to changes in immigration level than shifts toward higher incidence source countries. Relative constancy in foreign-born TB incidence is explained by a complex convergence of several factors. Immigrants born in high-incidence countries who arrived ≤ 2 yrs ago and were aged 15-34 yrs upon arrival constitute high-yield targets for preventive therapy.

Demographic, laboratory and clinical characteristics of HIV-positive tuberculosis cases in Canada

BACKGROUND

Human immunodeficiency virus (HIV) is an important risk factor for the global incidence and mortality of tuberculosis (TB) and has had a tremendous impact on the epidemiology and the control of the disease. The purpose of this study was to determine the demographic, laboratory and clinical characteristics of HIV-positive TB cases in Canada as compared to HIV-negative cases.

METHODS

TB cases reported to the Canadian TB Reporting System (CTBRS) from 1997 to 2006 were retrospectively reviewed and for those with known HIV serostatus, the distributions of age, sex, country of birth, smear and culture positivity, drug resistance, site of disease and treatment outcome were compared.

RESULTS

2710 TB cases had a report of an HIV test with a 12.9% positivity rate. HIV-positive cases were more likely to be 30-44 years old, male, Canadian born non-Aboriginal or African born. Sputum and lymph node biopsies were significantly more likely to be smear-positive and sputum was more likely to be culture positive. Anti-TB drug resistant rates were similar, except for lower streptomycin resistance in new HIV-positive cases. HIV-positive cases were significantly more likely to present with miliary or central nervous system TB, to have multi-system disease, to have lower treatment success rates (66.4% versus 88.5%) and to have a 5.6 higher case-fatality rate.

INTERPRETATION

HIV-positive cases have a different demographic profile, present with more advanced and severe forms of disease, have poorer treatment outcomes and higher mortality. All TB cases should be tested for HIV so as to offer appropriate case management and treatment.

CNS tuberculosis: a longitudinal analysis of epidemiological and clinical features

In a prospective Canadian cohort of 82 764 patients with tuberculosis (TB), the risk of developing central nervous system manifestations of TB (CNS-TB) (1%) was higher among younger, female, Aboriginal and foreign-born persons (P < 0.005), together with an elevated mortality risk (RR 4.23), compared to controls with only pulmonary TB. TB detection was lower in the CNS-TB group (P < 0.005), while the likelihood of being cured was also reduced (P < 0.005). CNS-TB remains a serious complication of TB in the industrialised world.

Stop TB-Halte à la Tuberculose-Canada: engaging industrialised nations in the challenge to meet global targets

The Stop TB Partnership has engaged the 22 high-burden countries in a drive toward the goal of finding 70% of cases and curing 85% by 2005. Traditional partners, aid agencies and governments of industrialised nations have joined the Partnership, but the broader range of civil society remains outside the discourse, risking disinterest on the part of the donor community. Stop TB-Halte à la Tuberculose-Canada was organised to engage new partners to support the Canadian government's commitment to the goal of reducing poverty and diseases of poverty, including tuberculosis, by 50% by 2010. The successes and challenges are explored, and the possibility raised that having a Stop TB movement in every country will ensure that support is sustained and goals of global tuberculosis control reached.