The contribution of country of origin to the epidemiology, incidence and transmission of Mycobacterium tuberculosis in New York City, 2001-2008

Statement of problem. Tuberculosis (TB) rates in the United States (US) have declined steadily for the past 15 years. However, this decline has taken place disproportionately among the US-born, resulting in a dramatic increase in the proportion of foreign-born cases over the same time period. While numerous studies have presented differences in incidence, patient characteristics and clustering between US-born and foreign-born TB patients, few have evaluated these differences by country of origin.;Methods. A retrospective population-based cohort analysis was conducted for incident TB patients diagnosed in New York City (NYC) between January 1, 2001 and December 31, 2008. Demographic, clinical, social and genotype characteristics were abstracted from data collected by NYC Department of Health and Mental Hygiene (DOHMH) staff during routine TB control activities. Incidence rates, patient characteristics and clustering information were stratified by patient country of birth and analyzed. A sub-analysis was conducted comparing characteristics and incidence rates of Tibetan TB patients to non-Tibetan TB patients.;Results. There were 8,199 active TB cases diagnosed in NYC between January 1, 2001 and December 31, 2008 with known country of origin. This population represented 143 countries, with 80% of patients hailing from one of 20 countries and 15% from the remaining 123. Countries with the highest NYC incidence rates—including Indonesia, Liberia, Cambodia and Ethiopia—were not necessarily those with the largest populations in NYC. Overall, rates of homelessness and substance abuse were low among foreign-born patients compared to US-born patients; other patient characteristics differed dramatically across groups by country of origin. Proportion of isolates clustered varied by country of origin from 12% in the Bangladeshi population to 68% among the Guyanese. Clustering rates varied across country of birth. The Tibetan community in NYC, though relatively small, had exceptionally high rates of TB, and a higher proportion of MDR-TB and XDR-TB than other comparable populations.;Conclusion. While foreign-born TB patients in NYC share certain characteristics, our data show that they are largely a heterogeneous group. With the proportion of foreign-born TB cases increasing nationwide, analysis of population-based data by country of origin can help shape interventions to reduce TB incidence.