The early identification of clusters of persons with tuberculosis (TB) that will grow to become outbreaks creates an opportunity for intervention in preventing future TB cases. We used surveillance data (2009-2018) from the United States, statistically derived definitions of unexpected growth, and machine-learning techniques to predict which clusters of genotype-matched TB cases are most likely to continue accumulating cases above expected growth within a 1-year follow-up period. We developed a model to predict which clusters are likely to grow on a training and testing data set that was generalizable to a validation data set. Our model showed that characteristics of clusters were more important than the social, demographic, and clinical characteristics of the patients in those clusters. For instance, the time between cases before unexpected growth was identified as the most important of our predictors. A faster accumulation of cases increased the probability of excess growth being predicted during the follow-up period. We have demonstrated that combining the characteristics of clusters and cases with machine learning can add to existing tools to help prioritize which clusters may benefit most from public health interventions. For example, consideration of an entire cluster, not only an individual patient, may assist in interrupting ongoing transmission.

BACKGROUND:A single 2-year National Health and Nutrition Examination Survey (NHANES) cycle is designed to provide accurate and stable estimates of conditions with prevalence of at least 10%. Recent NHANES-based estimates of a tuberculin skin test (TST) ≥10 mm in the noninstitutionalized US civilian population are at most 6.3%. METHODS:NHANES included a TST in 1971-1972, 1999-2000, and 2011-2012. We examined the robustness of NHANES-based estimates of the US population prevalence of a skin test ≥10 mm with a bias analysis that considered the influence of non-US birth distributions and within-household skin test results, reclassified borderline-positive results, and adjusted for TST item nonresponse. RESULTS:The weighted non-US birth distribution among NHANES participants was similar to that in the overall US population; further adjustment was unnecessary. We found no evidence of bias due to sampling multiple participants per household. Prevalence estimates changed 0.3% with reclassification of borderline-positive TST results and 0.2%-0.3% with adjustment for item nonresponse. CONCLUSIONS:For estimating the national prevalence of a TST ≥10 mm during these three survey cycles, a conventional NHANES analysis using the standard participant weights and masked design parameters that are provided in the public-use datasets appears robust. See video abstract at, http://links.lww.com/EDE/B636.

Increased testing and treatment of latent tuberculosis infection (LTBI) among US-residents who were born (or lived) in countries with high rates of TB can hasten progress toward TB elimination. We calculated LTBI prevalence using QuantiFERON®-TB Gold In-Tube results from the 2011 to 2012 National Health and Nutrition Examination Survey (NHANES). LTBI prevalence was highest for persons born in India (31.7%, 95% confidence interval [21.2, 44.5]). Non-Hispanic white persons had the lowest LTBI prevalence (6.3% [1.9, 18.9]). TB reactivation rate, defined as the number of TB cases not associated with recent transmission per 100 person-years of life with LTBI, was highest for persons born in Vietnam [0.183 (0.117, 0.303)]. Reactivation rates were lower among persons who had resided in the United States for ≥ 10 years than among those who had resided for < 10 years. Results among high risk populations can guide LTBI targeted testing and treatment among non-U.S.-born residents.

INTRODUCTION:Diabetes might confer a modestly increased risk of latent tuberculosis infection, which without treatment can progress to active tuberculosis disease. Three recent analyses of the National Health and Nutrition Examination Survey found a positive association between diabetes and a positive test for Mycobacterium tuberculosis infection. This study examines whether prevalence of a positive test still varies by diabetes status after stratifying by race/ethnicity. METHODS:This cross-sectional analysis used the public-use National Health and Nutrition Examination Survey 2011-2012 data sets and was conducted in 2018-2019. Interview and examination results for 5,560 adult participants yielded estimates for 219 million U.S. adults in the 4 largest race/ethnicity groups. The weighted prevalence of positive tuberculin skin test or interferon-gamma release assay by diabetes status was ascertained in each group. RESULTS:Among white and black adults, diabetes was associated with no difference in positive skin test prevalence and little difference in positive interferon-gamma release assay prevalence. The positive assay prevalence difference was +14.5% (95% CI=2.3%, 26.7%) among Hispanic and +9.9% (95% CI=1.2%, 18.6%) among Asian adults, when comparing those with diabetes with those with neither diabetes nor prediabetes. Based on assay results, 23.6% (95% CI=14.0%, 36.9%) of Hispanic and 27.2% (95% CI=19.6%, 36.5%) of Asian adults with diabetes also had latent tuberculosis infection. CONCLUSIONS:Hispanic and Asian subpopulation results drove much of the previously reported positive association between diabetes and a positive test for M. tuberculosis infection. Hispanic and Asian adults with diabetes might particularly benefit from screening and treatment for latent tuberculosis infection.

The US Centers for Disease Control and Prevention recommends screening populations at increased risk for tuberculosis (TB), including persons born in countries with high TB rates. This approach assumes that TB risk for expatriates living in the United States is representative of TB risk in their countries of birth. We compared US TB rates by country of birth with corresponding country rates by calculating incidence rate ratios (IRRs) (World Health Organization rate/US rate). The median IRR was 5.4. The median IRR was 0.5 for persons who received a TB diagnosis <1 year after US entry, 4.9 at 1 to <10 years, and 10.0 at >10 years. Our analysis suggests that World Health Organization TB rates are not representative of TB risk among expatriates in the United States and that TB testing prioritization in the United States might better be based on US rates by country of birth and years in the United States.

Although considerable progress has been made in reducing US tuberculosis incidence, the goal of eliminating the disease from the United States remains elusive. A continued focus on preventing new tuberculosis infections while also identifying and treating persons with existing tuberculosis infection is needed. Continued vigilance to ensure ongoing control of tuberculosis transmission remains key.

To refine estimates of how many persons in the United States are candidates for treatment of latent tuberculosis, we removed from analysis persons who self-reported prior treatment on the National Health and Nutrition Examination Survey 2011–2012. We estimate that 12.6 million persons could benefit from treatment to prevent active tuberculosis.

Objectives To assess changes in US tuberculosis (TB) incidence rates by age, period, and cohort effects, stratified according to race/ethnicity and nativity. Methods We used US National Tuberculosis Surveillance System data for 1996 to 2016 to estimate trends through age-period-cohort models. Results Controlling for cohort and period effects indicated that the highest rates of TB incidence occurred among those 0 to 5 and 20 to 30 years of age. The incidence decreased by age for successive birth cohorts. There were greater estimated annual percentage decreases among US-born individuals (-7.3%; 95% confidence interval [CI] = -7.5, -7.1) than among non-US-born individuals (-4.3%; 95% CI = -4.5, -4.1). US-born individuals older than 25 years exhibited the largest decreases, a pattern that was not reflected among non-US-born adults. In the case of race/ethnicity, the greatest decreases by nativity were among US-born Blacks (-9.3%; 95% CI = -9.6, -9.1) and non-US-born Hispanics (-5.7%; 95% CI = -6.0, -5.5). Conclusions TB has been decreasing among all ages, races and ethnicities, and consecutive cohorts, although these decreases are less pronounced among non-US-born individuals.

We previously reported use of genotype surveillance data to predict outbreaks among incident tuberculosis clusters. We propose a method to detect possible outbreaks among endemic tuberculosis clusters. We detected 15 possible outbreaks, of which 10 had epidemiologic data or whole-genome sequencing results. Eight outbreaks were corroborated.

We used tuberculosis genotyping results to derive estimates of prevalence of latent tuberculosis infection in the United States. We estimated <1% prevalence in 1,981 US counties, 1%–<3% in 785 counties, and >3% in 377 counties. This method for estimating prevalence could be applied in any jurisdiction with an established tuberculosis surveillance system.

In 2011–2012, 6,328,000 foreign-born persons in the United States were estimated to have latent tuberculosis infection (LTBI). Estimates of LTBI prevalence by subpopulation are needed to facilitate testing and treatment to prevent tuberculosis (TB) disease. Studying subpopulations by race/ethnicity would improve understanding of LTBI burden in the USA. Quantiferon Gold In-tube (QFT-GIT) blood tests were performed among civilian, noninstitutionalized persons >6 years of age as part of the 2011–2012 National Health and Nutrition Examination Survey (NHANES). LTBI prevalence and 95% confidence intervals (CI) were calculated by adjusting for complex survey design and QFT-GIT sensitivity and specificity. Reactivation rates were calculated using NHANES LTBI prevalence and the number of TB cases reported to the National TB Surveillance System that were not associated with recent transmission. All calculations used U.S. Census Bureau population. We compared three foreign-born subpopulations: all foreign-born; non-Hispanic Asian, non-Hispanic black or Hispanic; and non-Hispanic whites. QFT-GIT results were available for 1,955 foreign-born persons. LTBI prevalence was 19.1% (95% CI 15.0, 23.9) among foreign-born non-Hispanic Asian, non-Hispanic black or Hispanic subpopulation compared with 6.3% (1.9, 18.9) among foreign-born non-Hispanic whites and 16.9% (13.1, 21.5) among all foreign-born. The LTBI reactivation rate among foreign-born non-Hispanic whites was 0.062 (0.021, 0.203) per 100 person-years; reactivation rates per 100 person-years were similar for all foreign-born (0.088 [0.069, 0.114]) and non-Hispanic Asian, non-Hispanic black or Hispanic subpopulation (0.091 [0.073, 0.116]). Although LTBI prevalence was higher among the foreign-born non-Hispanic Asian, non-Hispanic black or Hispanic subpopulation than the foreign-born non-Hispanic white subpopulation the difference was not statistically significant at the 0.05 level. However, due to small sample size, estimates for foreign-born non-Hispanic whites should be interpreted with caution. These results may help guide LTBI targeted testing and treatment. All authors: No reported disclosures.

The majority of tuberculosis (TB) cases in the United States are attributable to reactivation of latent TB infection (LTBI) (1). LTBI refers to the condition when a person is infected with Mycobacterium tuberculosis without signs and symptoms, or radiographic or bacteriologic evidence of TB disease. CDC and the U.S. Preventive Services Task Force (USPSTF) recommend screening populations at increased risk for LTBI, including persons who have lived in congregate settings at high risk and persons who were born in, or are former residents of countries with TB incidence ≥20 cases per 100,000 population (2-4). In 2015, foreign-born persons constituted 66.2% of U.S. TB cases (5). During the past 30 years, screening of persons from countries with high TB rates has focused on overseas screening for immigrants and refugees, and domestic screening for persons who have newly arrived in the United States (6,7). However, since 2007, an increasing number and proportion of foreign-born patients receiving a diagnosis of TB first arrived in the United States ≥10 years before the development and diagnosis of TB disease. To better understand how this group of patients differs from persons who developed TB disease and received a diagnosis <10 years after U.S. arrival, CDC analyzed data for all reported TB cases in the United States since 1993 in the National TB Surveillance System (NTSS). After adjusting for age and other characteristics, foreign-born persons who arrived in the United States ≥10 years before diagnosis were more likely to be residents of a long-term care facility or to have immunocompromising conditions other than human immunodeficiency virus (HIV) infection. These findings support using the existing CDC and USPSTF recommendations for TB screening of persons born in countries with high TB rates regardless of time since arrival in the United States (2,3).

Tuberculosis is an infectious disease that may result from recent transmission or from an infection acquired many years in the past; there is no diagnostic test to distinguish the two causes. Cases resulting from recent transmission are particularly concerning from a public health standpoint. To describe recent tuberculosis transmission in the United States, we used a field-validated plausible source-case method to estimate cases likely resulting from recent transmission during January 2011-September 2014. We classified cases as resulting from either limited or extensive recent transmission based on transmission cluster size. We used logistic regression to analyze patient characteristics associated with recent transmission. Of 26,586 genotyped cases, 14% were attributable to recent transmission, 39% of which were attributable to extensive recent transmission. The burden of cases attributed to recent transmission was geographically heterogeneous and poorly predicted by tuberculosis incidence. Extensive recent transmission was positively associated with American Indian/Alaska Native (adjusted prevalence ratio [aPR] = 3.6 (95% confidence interval [CI] 2.9-4.4), Native Hawaiian/Pacific Islander (aPR = 3.2, 95% CI 2.3-4.5), and black (aPR = 3.0, 95% CI 2.6-3.5) race, and homelessness (aPR = 2.3, 95% CI 2.0-2.5). Extensive recent transmission was negatively associated with foreign birth (aPR = 0.2, 95% CI 0.2-0.2). Tuberculosis control efforts should prioritize reducing transmission among higher-risk populations.

Tuberculosis genotyping data are frequently used to estimate the proportion of tuberculosis cases in a population that are attributable to recent transmission (RT). Multiple factors influence genotype-based estimates of RT and limit the comparison of estimates over time and across geographic units. Additionally, methods used for these estimates have not been validated against field-based epidemiologic assessments of RT. Here we describe a novel genotype-based approach to estimation of RT based on the identification of plausible-source cases, which facilitates systematic comparisons over time and across geographic areas. We compared this and other genotype-based RT estimation approaches with the gold standard of field-based assessment of RT based on epidemiologic investigation in Arkansas, Maryland, and Massachusetts during 1996-2000. We calculated the sensitivity and specificity of each approach for epidemiologic evidence of RT and calculated the accuracy of each approach across a range of hypothetical RT prevalence rates plausible for the United States. The sensitivity, specificity, and accuracy of genotype-based RT estimates varied by approach. At an RT prevalence of 10%, accuracy ranged from 88.5% for state-based clustering to 94.4% with our novel approach. Our novel, field-validated approach allows for systematic assessments over time and across public health jurisdictions of varying geographic size, with an established level of accuracy.

As one of the three West African countries highly affected by the 2014-2015 Ebola virus disease (Ebola) epidemic, Liberia reported approximately 10,000 cases. The Ebola epidemic in Liberia was marked by intense urban transmission, multiple community outbreaks with source cases occurring in patients coming from the urban areas, and outbreaks in health care facilities (HCFs). This report, based on data from routine case investigations and contact tracing, describes efforts to stop the last known chain of Ebola transmission in Liberia. The index patient became ill on December 29, 2014, and the last of 21 associated cases was in a patient admitted into an Ebola treatment unit (ETU) on February 18, 2015. The chain of transmission was stopped because of early detection of new cases; identification, monitoring, and support of contacts in acceptable settings; effective triage within the health care system; and rapid isolation of symptomatic contacts. In addition, a "sector" approach, which divided Montserrado County into geographic units, facilitated the ability of response teams to rapidly respond to community needs. In the final stages of the outbreak, intensive coordination among partners and engagement of community leaders were needed to stop transmission in densely populated Montserrado County. A companion report describes the efforts to enhance infection prevention and control efforts in HCFs. After February 19, no additional clusters of Ebola cases have been detected in Liberia. On May 9, the World Health Organization declared the end of the Ebola outbreak in Liberia.

A review of 26 tuberculosis outbreaks in the United States (2002-2011) showed that initial source case-patients had long infectious periods (median 10 months) and were characterized by substance abuse, incarceration, and homelessness. Improved timeliness of diagnosis and thorough contact investigations for such cases may reduce the risk for outbreaks.

In 2013, a total of 9,588 new tuberculosis (TB) cases were reported in the United States, with an incidence rate of 3.0 cases per 100,000 population, a decrease of 4.2% from 2012. This report summarizes provisional TB surveillance data reported to CDC in 2013. Although case counts and incidence rates continue to decline, certain populations are disproportionately affected. The TB incidence rate among foreign-born persons in 2013 was approximately 13 times greater than the incidence rate among U.S.-born persons, and the proportion of TB cases occurring in foreign-born persons continues to increase, reaching 64.6% in 2013. Racial/ethnic disparities in TB incidence persist, with TB rates among non-Hispanic Asians almost 26 times greater than among non-Hispanic whites. Four states (California, Texas, New York, and Florida), home to approximately one third of the U.S. population, accounted for approximately half the TB cases reported in 2013. The proportion of TB cases occurring in these four states increased from 49.9% in 2012 to 51.3% in 2013. Continued progress toward TB elimination in the United States will require focused TB control efforts among populations and in geographic areas with disproportionate burdens of TB.