A case control study of risk factors for bovine brucellosis in KwaZulu-Natal South Africa

Abstract

Brucella abortus, a major cause of bovine brucellosis, is a facultative intracellular, gram-negative pathogen that infects mammals by replicating inside phagocytic cells of the reticulo-endothelial system and in trophoblastic cells of gravid placentae. As a result, it causes reproductive failure in cattle, with significant economic and animal health implications. It is also an important zoonosis. Few epidemiological studies of brucellosis have been undertaken in South Africa and consequently, little is known about the drivers of infection. A case-control study was therefore undertaken; 73 case and 102 control herds were recruited from the northern part of KwaZulu-Natal. These district municipalities were chosen because six had experienced cases of brucellosis, either in communal or commercial herds. Livestock owners or employees were interviewed using pre-tested questionnaires. A range of risk factors were identified and assessed including herd characteristics, management factors and knowledge of farm personnel. The risk factors identified were the herd size, with the odds increasing with increase in herd size up to 26 cattle, the number of and heifers, presence of sheep and goats and, number of sheep and goats, while being government sponsored and knowing the status of neighbouring farm was (protective).The presence of wild ruminants in the neighbouring farm brucellosis clinical signs in cattle and owners receiving training in the control of brucellosis were found to be an indication of risk. The study provided valuable information on drivers for brucellosis and will assist owners and programme managers in the control of bovine brucellosis and thus contribute to the on-going eradication programs in KwaZulu-Natal.