Risk assessment in zoonotic tuberculosis in Mbarara, the main milk basin of Uganda

Abstract

Mycobacterium bovis, the cause of tuberculosis in cattle, sometimes causes disease in humans: transmission from cattle to humans is mainly by ingestion of raw cattle products from infected animals, and transmission by inhalation is possible when there is prolonged contact. This study was carried out in tuberculosis patients from Mbarara, a major cattle keeping region in Uganda, to determine species of Mycobacterium responsible for the disease; whether M. bovis causes disease in humans and if so, factors that promote transmission from cattle to humans. A total of 90 patients were recruited. Finding of one case of M. bovis would imply prevalence of bovine tuberculosis of at least 5.0% (95% confidence). A suitable specimen was obtained from consecutive smear-positive patients attending  barara Hospital after informed consent. Disease was confirmed by microscopy. A questionnaire to determine ingestion of raw cattle products/prolonged association with cattle was administered to each patient. Specimens were processed and cultured on Lowenstein-Jensen medium at the National Tuberculosis Reference Laboratory. Molecular techniques were carried out on isolates at Montpellier (France) for species
identification. Of the 70 culture-positive samples no case of M. bovis was found. M. bovis is probably not a major public health problem in Mbarara district.

Keywords: Mycobacterium bovis, Mycobacterium tuberculosis, Uganda, risk assessment