The epidemiology of tuberculosis in cattle and humans living in the wildlife-livestock-human interface in the rural Mnisi community Mpumalanga province South Africa

Abstract

The aim of this study was to investigate the prevalence and epidemiological significance of tuberculosis (TB) in bovine and humans living at a wildlife/livestock/human interface, as well as the risk factors associated with TB transmission at that interface. The Mnisi community was chosen as it is located at the western border of the Kruger National park (KNP) and enables research at the wildlife/livestock/human interface. The first objective of the study entailed investigating the presence of bovine tuberculosis (BTB) in 10% of Mnisi?s livestock, using the comparative intradermal skin test. A low individual prevalence of 0.33 % (95% CI.0.14 ? -0.79) was detected. Further investigations into the causative agent in livestock, using genotyping techniques identified the KNP parental strain, M. bovis KNP VNTR -1 strain.1 Supporting records from the provisional Mpumalanga Veterinary Services and the physical location of dip-tanks where BTB was detected, it was established the infection was a result of spillback infection from wildlife in the neighbouring KNP. The epidemiological significance of BTB in human TB was investigated through the isolation and genetic characterisation of the Mycobacterium tuberculosis complex (MTBC) strain population in the Mnisi community. Mycobacterium bovis was not detected in the human population. However, a high genetic diversity of M. tuberculosis was observed among the 13 isolates obtained.The M. tuberculosis isolates were identified as the following eight families: T; Beijing; LAM 11_ZWE; EAI5; MANU1; X1; X2; and S families. The predominant lineage was as T family, sub-lineage ST53. Based on the high diversity (8 clusters/13isolates) and the predominance of the T family, it was concluded that the TB population structure within the Mnisi community was largely impacted by human migration from urban towns and neighbouring Mozambique. A questionnaire was administered to investigate BTB transmission risk factors at the livestock/human interface. It was established that there were low risk levels of BTB transmission at the human/livestock interface mainly based on the fact that the majority of the households in the community obtained pasteurised milk commercially, and although undercooked/raw meat and organs were preferred, the majority of respondents reported that they discarded the meat if changes in meat quality were observed.