The Importance of Recent Infection withMycobacterium tuberculosisin an Area with High HIV Prevalence: A Long‐Term Molecular Epidemiological Study in Northern Malawi

Abstract

BackgroundThe proportion of cases of tuberculosis due to recent infection can be estimated in long-term population-based studies using molecular techniques. Here, we present what is, to our knowledge, the first such study in an area with high human immunodeficiency virus (HIV) prevalence MethodsAll patients with tuberculosis in Karonga District, Malawi, were interviewed. Isolates were genotyped using restriction-fragment–length polymorphism (RFLP) patterns. Strains were considered to be “clustered” if at least 1 other patient had an isolate with an identical pattern ResultsRFLP results were available from 83% of culture-positive patients from late 1995 to early 2003. When strains with ConclusionsThe proportion clustered found in the present study was among the highest in the world, suggesting high rates of recent transmission. The association with HIV infection in older adults may suggest that HIV has a greater impact on disease caused by recent transmission than on that caused by reactivation