Reported Tuberculosis in the United States, 2020
Estimates of Recent Transmission
Control of recent transmission is an essential component of the national strategy to eliminate TB disease in the United States. CDC uses genotyping data to estimate the number of TB cases that are attributed to recent transmission. Estimates are based on whether a TB case has a plausible source case with a matching genotype in a person with TB disease who resides within 10 miles and was diagnosed within 2 years prior to the case.
State and local TB programs may use these estimates to monitor trends in their jurisdictions, and to assist in planning and prioritizing TB control activities.
The number of cases attributed to recent transmission declined by 10.8%, from 1,712 in 2017–2018 to 1,527 during 2019–2020.
- The 12.5% of genotyped cases attributed to recent transmission during 2019–2020 is comparable to the previous 2-year period 2017–2018 (12.6%).
- While estimates of recent transmission vary across reporting areas, all but seven reporting areas had at least one case reported in 2019–2020 that was attributed to recent transmission (TB Estimated to be Attributed to Recent Transmission: Reporting Areas, 2019–2020).
Although 71.5% of reported TB cases were among non-U.S.–born persons during 2019–2020 (TB by Origin of Birth: 1993–2020), most cases (54.7%) attributed to recent transmission were among U.S.-born persons (Characteristics of TB Estimated to be Attributed to Recent Transmission: 2019–2020).
The percentage of TB cases attributed to both recent transmission and extensive recent transmission increased in 2019–2020 compared with 2017–2018 in some groups at increased risk for TB.
- Among persons with TB disease who reported injection drug use during 2019–2020, 33.3% and 13.2% were attributed to recent transmission and extensive recent transmission, respectively; in the previous 2-year period the percentages were 20.5% and 6.0%.
- Among persons who were incarcerated at the time of evaluation for TB disease during 2019–2020, 21.0% and 14.6% were attributed to recent transmission and extensive recent transmission, respectively, compared with 15.8% and 6.3% in the previous 2-year period.
See the Risk Factors webpage for more information.
Disparities in the estimated percentage of cases attributed to recent transmission and extensive recent transmission persist among certain racial and ethnic minority groups.
- The percentage of recent transmission is highest among American Indian or Alaska Native persons and was 44.6% in 2019–2020 compared with 40.4% in 2017–2018.
See the Demographics webpage for more information.
- Figure 1. Estimated Cases Attributed to Recent Transmission of TB, United States, 2019–2020
- Figure 2. Estimated Percentage of Extensive Recent Transmission of TB, United States, 2019–2020
- TB Estimated to be Attributed to Recent Transmission: Reporting Areas, 2019–2020
- TB Estimated to be Attributed to Recent Transmission: Counties with >5 Percent Estimated Extensive Recent Transmission, 2019–2020
- Characteristics of TB Cases Estimated to be Attributed to Recent Transmission: 2019–2020