Individual- and neighborhood-level contextual factors are associated with Mycobacterium tuberculosis transmission: genotypic clustering of cases in Michigan, 2004-2012.
Grace A Noppert, Zhenhua Yang, Philippa Clarke, Wen Ye, Peter Davidson, Mark L Wilson
Author Information
Grace A Noppert: Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor. Electronic address: grace.noppert@duke.edu.
Zhenhua Yang: Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor.
Philippa Clarke: Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor; Institute for Social Research, University of Michigan, Ann Arbor.
Wen Ye: Department of Biostatistics, University of Michigan School of Public Health, Ann Arbor.
Peter Davidson: Michigan Department of Health and Human Services, Lansing, MI.
Mark L Wilson: Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor.
PURPOSE: Using genotyping data of Mycobacterium tuberculosis isolates from new cases reported to the tuberculosis (TB) surveillance program, we evaluated risk factors for recent TB transmission at both the individual- and neighborhood- levels among U.S.-born and foreign-born populations. METHODS: TB cases (N = 1236) reported in Michigan during 2004 to 2012 were analyzed using multivariable Poisson regression models to examine risk factors for recent transmission cross-sectionally for U.S.-born and foreign-born populations separately. Recent transmission was defined based on spoligotype and 12-locus-mycobacterial interspersed repetitive unit-variable number tandem repeat typing matches of bacteria from cases that were diagnosed within 1 year of each other. Four classes of predictor variables were examined: demographic factors, known TB risk factors, clinical characteristics, and neighborhood-level factors. RESULTS: Overall, 22% of the foreign-born cases resulted from recent transmission. Among the foreign-born, race and being a contact of an infectious TB case were significant predictors of recent transmission. More than half (52%) of U.S.-born cases resulted from recent transmission. Among the U.S.-born, recent transmission was predicted by both individual- and neighborhood-level sociodemographic characteristics. CONCLUSIONS: Interventions aimed at reducing TB incidence among foreign-born should focus on reducing reactivation of latent infection. However, reducing TB incidence among the U.S.-born will require decreasing transmission among socially disadvantaged groups at the individual- and neighborhood- levels. This report fills an important knowledge gap regarding the contemporary social context of TB in the United States, thereby providing a foundation for future studies of public health policies that can lead to the development of more targeted, effective TB control.
