Sero-prevalence of bovine brucellosis in the Bojanala Region, North West Province, South Africa 2009-2013

Bovine brucellosis affects food safety, food security and human health in rural communities in the North West Province, South Africa. The World Organisation for Animal Health suggests routine sero-surveillance and vaccination of cattle for control and to prevent zoonotic transmission. Although sero-surveillance and subsidised vaccination have been in place for decades, data from Bojanala have not previously been analysed. The aim of this study was to retrospectively analyse historical data on routine sero-surveillance of bovine brucellosis and state subsidised vaccination, in communal, commercial and dairy cattle in the study area. This was a descriptive, cross-sectional retrospective analysis of records from all adult cows bled by the state veterinary services during routine sero-surveillance for bovine brucellosis, in the Bojanala Region, North West Province, between 2009 and 2013. Fewer communal (N = 11 815) and dairy (N = 6696), than commercial beef (N = 28 251) cows, were tested. Overall herd prevalence (33.33%), differed significantly from individual prevalence (3.18%) in all groups. Communal herds had both the highest herd prevalence (38.8%) and the highest individual prevalence (5.2%). Both herd and individual sero-prevalence were lowest in dairy cattle, possibly because registered dairy herds are routinely tested. Over the 5-year study period, only 24 086 (7.15%) of the 342 500 cows eligible for free vaccination, were vaccinated. The annual number of cattle tested was highly variable. Dairy cattle that were regularly tested had a significantly lower herd and individual prevalence. Herd prevalence would be useful for spatial mapping, whilst individual prevalence could better reflect the risk of zoonotic transmission.