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The goal for tuberculosis (TB) elimination in the United States is a TB disease incidence of less than 1 per million U.S. population by 2010, which requires that the latent TB infection (LTBI) prevalence be less than 1% and decreasing.To estimate the prevalence of LTBI in the U.S. population.Interviews and medical examinations, including tuberculin skin testing (TST), of 7,386 individuals were conducted in 1999-2000 as part of the National Health and Nutrition Examination Survey (NHANES), a nationally representative sample of the civilian, noninstitutionalized U.S. population. LTBI was defined as a TST measurement of/=10 mm. Associations of age, race/ethnicity, sex, poverty, and birthplace were assessed. Results among the 24- to 74-year-old subgroup were compared with NHANES 1971-1972 data.Estimated LTBI prevalence was 4.2%; an estimated 11,213,000 individuals had LTBI. Among 25- to 74-year-olds, prevalence decreased from 14.3% in 1971-1972 to 5.7% in 1999-2000. Higher prevalences were seen in the foreign born (18.7%), non-Hispanic blacks/African Americans (7.0%), Mexican Americans (9.4%), and individuals living in poverty (6.1%). A total of 63% of LTBI was among the foreign born. Among the U.S. born, after adjusting for confounding factors, LTBI was associated with non-Hispanic African-American race/ethnicity, Mexican American ethnicity, and poverty. A total of 25.5% of persons with LTBI had been previously diagnosed as having LTBI or TB, and only 13.2% had been prescribed treatment.In addition to basic TB control measures, elimination strategies should include targeted evaluation and treatment of individuals in high-prevalence groups, as well as enhanced support for global TB prevention and control.

Use of rifampin is required for short-course treatment regimens for tuberculosis. Tuberculosis caused by isolates of M. tuberculosis with resistance to rifampin and susceptibility to isoniazid is unusual, but it has been recognized through surveillance. Patients with tuberculosis (cases) with rifampin monoresistance were compared with HIV-matched controls with tuberculosis caused by a drug-susceptible isolate. A total of 77 cases of rifampin mono-resistant tuberculosis were identified in this multicenter study. Three were determined to be laboratory contaminants, and 10 cases had an epidemiologic link to a case with rifampin mono-resistant tuberculosis, suggesting primary acquisition of rifampin-resistant isolates. Of the remaining 64 cases and 126 controls, there was no difference between cases and controls with regard to age, sex, race, foreign birth, homelessness, or history of incarceration. Cases were more likely to have a history of prior tuberculosis than were controls. Of the 38 cases and 74 controls with HIV infection, there was no difference between cases and controls with regard to age, sex, race, foreign birth, homelessness, history of incarceration, or prior tuberculosis. Cases were more likely to have histories of diarrhea, rifabutin use, or antifungal therapy. Laboratory analysis of available isolates showed that there was no evidence of spread of a single clone of M. tuberculosis. Further studies are needed to identify the causes of the development of rifampin resistance in HIV-infected persons with tuberculosis and to develop strategies to prevent its emergence. Ridzon R, Whitney CG, McKenna MT, Taylor JP, Ashkar SH, Nitta AT, Harvey SM, Valway S, Woodley C, Cooksey R, Onorato IM. Risk factors for rifampin mono-resistant tuberculosis. AM J RESPIR CRIT CARE MED 1998;157:1881‐1884.

Despite the long-standing observation that tuberculosis (TB) case rates are higher among racial and ethnic minorities than whites in the United States (U.S.), the proportion of this increased risk attributable to socioeconomic status (SES) has not been determined. Values for six SES indicators (crowding, income, poverty, public assistance, unemployment, and education) were assigned to U.S. TB cases reported from 1987-1993 by ZIP code- and demographic-specific matching to 1990 U.S. Census data. TB risk between racial/ethnic groups was then evaluated by quartile for each SES indicator utilizing univariate and Poisson multivariate analyses. Relative risk (RR) of TB increased with lower SES quartile for all six SES indicators on univariate analysis (RRs 2.6-5.6 in the lowest versus highest quartiles). The same trend was observed in multivariate models containing individual SES indicators (RRs 1.8-2.5) and for three SES indicators (crowding, poverty, and education) in the model containing all six indicators. Tuberculosis risk increased uniformly between SES quartile for each indicator except crowding, where risk was concentrated in the lowest quartile. Adjusting for SES accounted for approximately half of the increased risk of TB associated with race/ethnicity among U.S.-born blacks, Hispanics, and Native Americans. Even more of this increased risk was accounted for in the final model, which also adjusted for interaction between crowding and race/ethnicity. SES impacts TB incidence via both a strong direct effect of crowding, manifested predominantly in overcrowded settings, and a TB-SES health gradient, manifested at all SES levels. SES accounts for much of the increased risk of TB previously associated with race/ethnicity.

Following an initial negative Mantoux tuberculin skin test, a second test, given as soon as 1 wk later, has been shown to elicit markedly larger reactions (boosting) in 20 to 40% of refugees tested in the United States. We conducted a study to determine the explanation for this phenomenon. Using the Mantoux method of intradermal skin testing, 2,469 refugees from Southeast Asia were initially tested with tuberculin followed by sequential retesting 7 and/or 90 d later. They were also tested initially with nontuberculous mycobacterial antigens. A high proportion (35.5%) of Southeast Asian refugees had reactions (> or = 10 mm induration) to an initial tuberculin test, and 30.9% of the nonreactors exhibited boosting on a subsequent tuberculin test. Boosting, unlike reactivity to the initial tuberculin test, was not associated with exposure to a person with tuberculosis. However, boosting was associated with reactivity to nontuberculous mycobacterial antigens and a history of bacille Calmette-Guerin (BCG) vaccination. Boosting in this population is therefore attributable to environmental exposure to nontuberculous mycobacteria that are endemic in Southeast Asia or to BCG vaccination, rather than to remote infection with Mycobacterium tuberculosis. Sequential tuberculin screening and preventive therapy of persons with boosted reactions is not recommended as a tuberculosis prevention strategy in this population.

There has been increasing interest in the potential association between occupation and the risk of tuberculosis. Therefore, we analyzed occupational information collected on all patients with clinically active tuberculosis in 29 states from 1984 to 1985. Census data were used to estimate the number of persons in each of the occupations. Information on employment and occupation was ascertained for 9,534 (99%) of the working age (16 through 64 yr) tuberculosis patients. The overall case rate of tuberculosis in this age group in the study areas was 8.4 per 100,000 persons, which was slightly lower than the national rate of 9.3 per 100,000 persons. As a group, health care workers had rates of tuberculosis similar to the general population (standardized morbidity ratio [SMR]: 1.0; 95% CI: 0.9 to 1.1). However, elevated rates were observed for inhalation therapists (SMR: 2.9; 95% CI: 1.2 to 6.0), and lower-paid health care workers (SMR: 1.3; 95% CI: 1.1 to 1.5). Elevated rates were also noted for funeral directors (SMR: 3.9; 95% CI: 2.2 to 6.1) and farm workers (SMR: 3.7; 95% CI: 3.4 to 4.1). These data suggest that even in communities with relatively low rates of tuberculosis certain occupations may be associated with an elevated risk.