Mycobacterium tuberculosis Transmission in a Country with Low Tuberculosis Incidence: Role of Immigration and HIV Infection

Abstract

Immigrants from high-burden countries and HIV-coinfected individuals are risk groups for tuberculosis (TB) in countries with low TB incidence. Therefore, we studied their role in transmission of Mycobacterium tuberculosis in Switzerland. We included all TB patients from the Swiss HIV Cohort and a sample of patients from the national TB registry. We identified molecular clusters by spoligotyping and mycobacterial interspersed repetitive-unit-variable-number tandem-repeat (MIRU-VNTR) analysis and used weighted logistic regression adjusted for age and sex to identify risk factors for clustering, taking sampling proportions into account. In total, we analyzed 520 Cavitary disease, male sex, and younger age were all associated with molecular clustering. In conclusion, most TB patients in Switzerland were foreign born, but transmission of M. tuberculosis was not more common among immigrants and was reduced in HIV-infected patients followed up in the national HIV cohort study. Continued access to health services and clinical follow-up will be essential to control TB in this population.

Molecular characterization of Mycobacterium tuberculosis complex in Gambella region, Southwest Ethiopia

“…The predominance of Euro-American lineage finding (also known as linage 4) in this study also similar with the reports of previous studies, reported as the dominant lineage in different regions of Ethiopia (Diriba et al, 2013;Firdessa et al, 2013;Tessema et al, 2013). In a study conducted in Switzerland, the Euro-American and Indo-Oceaninc linage proportion were 72.7 and 8.3% which are higher and lower respectively compared to the present study result (Fenner et al, 2012). In another study conducted in USA, the Euro-American linage prevalence was lower than the present finding which was 13.8% while, the Indo-Oceanic prevalence in this study was lower as compared to 22.6% (Eleanor et al, 2012).…”

Standard Genotyping Overestimates Transmission of Mycobacterium tuberculosis among Immigrants in a Low-Incidence Country

“…In addition, we included a random sample of 288 TB patients from the 4,221 patients with culture-confirmed TB reported to the National TB Surveillance Registry, and all of the drug-resistant TB patients reported in Switzerland (n ϭ 167) during the same period (categories not mutually exclusive). Twenty-four-locus MIRU-VNTR typing and spoligotyping were used for the molecular detection of transmission clusters (9). In this follow-up study, we performed WGS of the 90 M. tuberculosis isolates belonging to 1 of the 35 MIRU-VNTR typing/spoligotyping clusters.…”

“…In 2012, we conducted a nationwide study of the molecular epidemiology of TB in Switzerland as a collaborative project involving the Swiss HIV Cohort Study (SHCS), the National Center for Mycobacteria, diagnostic microbiology laboratories, departments of respiratory medicine and public health, and the Federal Office of Public Health (www.tb-network.ch) (9,(25)(26)(27)(28). The study setting was previously described in detail (9). Briefly, all of the patients in the SHCS diagnosed with TB between 2000 and 2008 were enrolled (n ϭ 93).…”

“…Immigrants from countries with a high TB incidence and HIV-infected populations are common risk groups in Switzerland, as in other European countries (4)(5)(6)(7)(8). We and others have previously shown that transmission of Mycobacterium tuberculosis occurs but is not more common among immigrants than in the native population (9)(10)(11)(12).…”

“…In contrast to standard genotyping methods, whole-genome sequencing (WGS) provides better resolution and has been used to study M. tuberculosis transmission (20)(21)(22)(23)(24). In this study, we reanalyzed transmis-sion clusters previously defined by MIRU-VNTR typing by using WGS to assess the transmission of M. tuberculosis among Swissand foreign-born TB patients (9).…”