Estimating and Evaluating Tuberculosis Incidence Rates Among People Experiencing Homelessness, United States, 2007-2016

Abstract

Objectives: Persons experiencing homelessness (PEH) are disproportionately affected by tuberculosis (TB). We estimate area-specific rates of TB among PEH and characterize the extent to which available data support recent transmission as an explanation of high TB incidence.

Methods: We estimated TB incidence among PEH using National Tuberculosis Surveillance System data and population estimates for the US Department of Housing and Urban Development's Continuums of Care areas. For areas with TB incidence higher than the national average among PEH, we estimated recent transmission using genotyping and a plausible source-case method. For cases with ≥1 plausible source case, we assessed with TB program partners whether available whole-genome sequencing and local epidemiologic data were consistent with recent transmission.

Results: During 2011-2016, 3164 TB patients reported experiencing homelessness. National incidence was 36 cases/100,000 PEH. Incidence estimates varied among 21 areas with ≥10,000 PEH (9-150 cases/100,000 PEH); 9 areas had higher than average incidence. Of the 2349 cases with Mycobacterium tuberculosis genotyping results, 874 (37%) had ≥1 plausible source identified. In the 9 areas, 23%-82% of cases had ≥1 plausible source. Of cases with ≥1 plausible source, 63% were consistent and 7% were inconsistent with recent transmission; 29% were inconclusive.

Conclusions: Disparities in TB incidence for PEH persist; estimates of TB incidence and recent transmission vary by area. With a better understanding of the TB risk among PEH in their jurisdictions and the role of recent transmission as a driver, programs can make more informed decisions about prioritizing TB prevention strategies.

FIGURE 1.

Change in tuberculosis (TB) incidence over time among entire US population¹ and persons experiencing homelessness,² United States, 2007–2016. 1TB incidence among the entire US population is shown for comparison based on published case rates. ²To estimate national TB incidence among persons experiencing homelessness (PEH), we divided the mean number of TB cases among persons with reported homelessness in the National Tuberculosis Surveillance System during fiscal years 2011–2016 by the national homeless population size estimate during 2016 reported in the Annual Homeless Assessment Report.