Rationale: The prevalence of pulmonary nontuberculous mycobacterial (NTM) infections in the United States appears to be rising, but it is unclear if this is due to enhanced detection or actual increases in the burden of infection. Temporal changes in the epidemiology of Mycobacterium intracellulare sensitization may help explain recently observed trends in pulmonary NTM infections.
Objectives: Describe the epidemiology of M. intracellulare sensitization in the United States in 1971-1972 and 1999-2000.
Methods: We studied nationally representative cohorts of the United States' noninstitutionalized civilian population participating in the 1971-1972 and 1999-2000 National Health and Nutrition Examination Surveys (NHANES). Participants were skin tested with M. intracellulare antigen and sensitization prevalence was compared across NHANES surveys and between participant subgroups. Logistic regression was used to identify associations between participant characteristics, environmental factors, and NTM sensitization.
Measurements and main results: The 1971-1972 and 1999-2000 NHANES cohorts included 1,490 and 7,384 individuals, respectively. Between 1971-1972 and 1999-2000, the prevalence of M. intracellulare sensitization increased from 11.2% (95% confidence interval, 9.2-13.5%) to 16.6% (95% confidence interval, 13.2-20.6%). On multivariate analysis of the 1999-2000 cohort, age, sex, race, birthplace, education, and occupation were strongly associated with M. intracellulare sensitization.
Conclusions: In 1999-2000, an estimated one in six persons in the United States demonstrated M. intracellulare sensitization, up from one in nine persons in 1971-1972. The observed rising prevalence of sensitization is consistent with observed increases in the rates of pulmonary NTM infections in the United States.