Tuberculosis — United States, 2017

Rebekah J. Stewart, MSN, MPH; Clarisse A. Tsang, MPH; Robert H. Pratt; Sandy F. Price; Adam J. Langer, DVM

Disclosures

Morbidity and Mortality Weekly Report. 2018;67(11):317-323. 

In This Article

Discussion

In 2017, the provisional TB case count and incidence were the lowest in the United States since national TB surveillance began in 1953;[1] however, the rate in 2017 (2.8 per 100,000) is still 28 times the U.S. elimination threshold of less than one case per million persons.[4] Since 2014, the annual percentage change in rate compared with the preceding year has slowed to an average decline of 2.0%. To achieve TB elimination by 2100, a sustained annual decline of 3.9% is required.§§ Previous studies have indicated that reactivation of LTBI, rather than recent transmission, is the primary driver of TB disease in the United States, accounting for >80% of all TB cases.[2] Ongoing efforts to prevent TB transmission must be sustained, and efforts to detect and treat LTBI, especially among groups at high risk, must be increased.

An epidemiologic model found that substantial (i.e., quadruple) increases in LTBI testing and treatment completion would accelerate progress toward TB elimination.[4] Several accepted treatment regimens are available for LTBI.[5] Among these, CDC encourages the use of shorter, rifamycin-based regimens, such as 4 months of rifampin or 3 months of once-weekly rifapentine plus isoniazid, which have better treatment completion rates[6] and are less hepatotoxic[7,8] than a regimen of 9 months of isoniazid. Improved treatment completion, less toxicity, and shorter treatment regimens can reduce morbidity and accelerate TB elimination in the United States.

Distinct disparities exist between populations affected by TB. Highly affected and vulnerable populations include persons housed in congregate settings and persons from countries with high TB prevalences. The U.S. Preventive Services Task Force (USPSTF) recommends screening for LTBI in populations at increased risk, including persons born in countries with high TB prevalences, regardless of length of residence in the United States and age;[3] this recommendation is consistent with a previously published report documenting an increasing proportion of TB diagnoses among non–U.S.-born persons living in the United States for ≥10 years.[9] In addition to USPSTF screening recommendations, CDC also recommends treatment of LTBI to reduce the number of persons developing TB disease.[5] Increased support of global TB elimination efforts would help to reduce global TB and LTBI prevalence, thereby indirectly reducing the incidence of reactivation TB in the United States among non–U.S.-born persons from higher-prevalence countries.

Spending time in congregate settings, such as homeless shelters, long-term care facilities, and correctional facilities, increases the risk for TB transmission. Most requests from state or local health departments for on-site CDC assistance arise from TB outbreaks involving congregate settings serving vulnerable populations.[10] The USPSTF recommends TB testing for persons who have lived in high-risk congregate settings, such as homeless shelters and correctional facilities.[3] Control of transmission requires not only preventing disease through treatment of LTBI, but also strong infection control practices in settings with increased risk for transmission.

The findings in this report are subject to at least two limitations. First, this analysis is limited to reported provisional TB cases and case rates for 2017; final results will be available in the fall of 2018. Second, case rates are calculated using 2017 population estimates as denominators.

Since 2015, TB case counts and rates in the United States have declined, in large part because of the work of local TB programs in detecting and treating persons with TB disease. Approximately 96% of persons with diagnosed TB disease in the United States complete therapy,[1] thereby limiting the risk for further transmission and development of MDR TB. TB is preventable through LTBI testing and treatment and implementation of effective infection control measures; however, TB elimination goals in the United States will not be achieved without steadfast engagement among public health partners and sustained prevention and control programs. Public health priorities for TB elimination in the United States include developing comprehensive and innovative approaches to diagnosing, treating, and monitoring LTBI; continued engagement by the United States in global TB control efforts; and enhanced efforts to prevent TB transmission in the United States, particularly in congregate settings.

§§Sustained annual percent decline to reach TB elimination calculated as the yearly incidence reduction necessary to get from current rate to one case per million persons in 2100.

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