MONDAY, May 4, 2026 (HealthDay News) -- Fifty large tuberculosis (TB) outbreaks were identified in 23 states during 2017 to 2023, mainly involving U.S.-born persons, according to research published in the April 30 issue of the U.S. Centers for Disease Control and Prevention Morbidity and Mortality Weekly Report.Kala M. Raz, M.P.H., from the CDC in Atlanta, and colleagues describe large TB outbreaks during 2017 to 2023 using national genomic and TB case surveillance data.The researchers identified 50 large TB outbreaks with 10 or more related TB cases in a three-year period, involving 1,092 cases in 23 states. The researchers found that compared with 61,993 other people who received a TB diagnosis during this period, those included in the large outbreaks were more often U.S.-born (79 versus 26 percent) and more often reported substance use (27 versus 12 percent), homelessness (9 versus 5 percent), and incarceration (11 versus 3 percent). About one-quarter of the large outbreak-related cases were identified through contact tracing; these cases less often had clinical markers of highly infectious disease than large outbreak cases identified through other methods (23 versus 61 percent), suggesting that contact tracing may have facilitated earlier diagnosis. Thirty-four and 13 of the 50 large outbreaks were primarily associated with family or social networks and with congregate settings, respectively."Outbreak prevention and response strategies must also overcome barriers to diagnosis and treatment associated with homelessness and substance use," the authors write. "In addition, there is a need to build trust with affected persons and communities directly and through partnerships with local organizations and service providers."Abstract/Full Text.Sign up for our weekly HealthDay newsletter