On the Relationship between Age, Annual Rate of Infection, and Prevalence ofMycobacterium tuberculosisin a South African Township

Abstract

To the Editor—A recent article [1] reported a very high prevalence of infection due to Mycobacterium tuberculosis among children 5–17 years of age in a South African township. The results are based on tuberculin skin tests performed in 2007 for 829 children 5–17 years of age and are listed in table 1. From such age-specific prevalences, it was possible to estimate the mean annual risk of infection experienced by each cohort.