Resistance and Susceptibility to Mycobacterium Tuberculosis Infection and Disease in Tuberculosis Households in Kampala, Uganda

Abstract

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a major public health problem. Household contact studies identify children and adults along the spectrum from Mtb exposure to disease. In the Kawempe Community Health Study, conducted in Kampala, Uganda, 872 culture-confirmed pulmonary TB cases and their 2,585 contacts were enrolled between 2002–2012 and followed for up to 2 years each. Risk factors identified by time-to-event analysis for secondary TB differed among children, women and men. Younger age (P = 0.0061), HIV (P = 0.0002), thinness (P = 0.01), absent Bacille Calmette-Guérin vaccine (P = 0.002) and epidemiologic risk score (P < 0.0001) were risks for children. For women, risks were HIV (P < 0.0001), thinness (WHO criteria; P < 0.0001) and epidemiologic risk score (P = 0.003). For men, HIV (P = 0.0007) and low body mass index (P = 0.008) resulted in faster progression to TB. Tuberculin skin testing (TST) identified contacts with Mtb infection and those with persistently negative TST (PTST−). Risks for faster time to Mtb infection were identified, and included age (P = 0.0007), baseline TST induration (P < 0.0001), and epidemiologic risk score (P < 0.0001) only in children. PTST− comprised 10% of contacts but had no unique epidemiologic characteristics in adults. The burden of Mtb infection and disease is high in TB households, and risk factors for progression from exposure to infection and disease differ among children, women and men.