Notes from the field: tuberculosis cluster associated with homelessness--Duval County, Florida, 2004-2012.

Despite a decrease in incidence of tuberculosis (TB) in Duval County, Florida, from 102 cases (11.2 per 100,000 population) in 2008 to 71 cases (8.2 per 100,000) in 2011,* analysis of Mycobacterium tuberculosis genotyping data revealed a substantial increase in the percentage of TB cases with the same genotype.† That percentage increased from 27% (10 of 37) of genotyped cases in 2008 to 51% (30 of 59) of genotyped cases in 2011 (Florida Department of Health, unpublished data, 2012). During this period, the percentage of patients with this genotype who were homeless or who abused substances also increased. Because of concern over potential ongoing TB transmission involving these hard-to-reach populations, the Duval County Health Department, Florida Department of Health, and CDC conducted an investigation during February 15-March 13, 2012. As of March 13, review of medical records and interviews with TB patients had identified 99 cases related to the cluster based on matching genotype results and epidemiologic links (48 cases), matching genotype only (22), epidemiologic links only (22), or common social risk factors for TB (e.g., homelessness, incarceration, or substance abuse within 1 year of TB diagnosis) and suspected epidemiologic links (seven). The first known case with a matching genotype occurred in 2004.