Mycobacterium bovis infection in cattle at the wildlife/livestock interface in northern KwaZulu-Natal province, South Africa

Abstract

A cross-sectional study was carried out in Northern KwaZulu-Natal at the wildlife/livestock interface to determine the prevalence of Mycobacterium bovis infection in cattle using a modified BOVIGAM® interferon gamma assay (IFN-γ). Although cattle are known as the primary host, M. bovis can also affect other domestic animals, wildlife and humans. Using a random sampling technique, whole blood samples were collected from 387 cattle registered at two dip tanks (Mpempe and Nkomo) in the uMkhanyakude district, which consisted of 267 females and 120 males from a total of 100 herds. The apparent M. bovis prevalence rate at animal level was 13.9% (95% confidence interval (CI) 10.6 - 17.4) and the true prevalence indicated a similar prevalence rate of 13.6% (95% CI 10.2 - 16.9). The apparent and true prevalence rate at Nkomo dip tank was 7.9% (95% CI 4.4 - 13.6) and 5.7% (95% CI 1.4 - 11.6) respectively. The apparent and true prevalence rates at Mpempe dip tank were almost similar: 17.3% (95% CI 13.1 - 22.5) and 18% (95% CI 11.9 - 24.1) respectively. At Mpepe dip tank 20/52 (39%) of the farmers had at least one test positive animal, whilst at Nkomo dip tank, this figure was 8/48 (17%). Based on sex, 11 (9.1%, 95% CI 3.9 - 14.2) of the males and 43 (16.1%, 95% CI 11.7 - 20.5) of the females tested positive with the assay. This study forms part of a One Health project at the wildlife/livestock interface. Confirmation of infection will be done through isolation and culture of tissues from test positive animals. The isolates will be genotyped and compared with isolates from wildlife, to monitor M. bovis transmission at the wildlife/livestock interface.