Identifying high risk areas for foot-and-mouth disease (FMD) outbreaks in South Africa

Abstract

Foot-and-mouth disease (FMD) is a controlled (notifiable) disease in accordance with the South African Animal Diseases Act (Act 35) of 1984. In 1996, the International Committee on FMD of the OIE endorsed South Africa’s FMD free status without vaccination. According to the OIE status, the areas excluded from the free zone were the endemically infected Kruger National Park and the FMD protection areas. During the previous 15 years, at least one FMD outbreak has occurred per year in the protection zone with the exceptions being 2005, 2007, and 2014. Continuing outbreaks threaten the FMD-free status of the country; outbreaks raise concerns about the efficiency and sustainability of FMD control measures within the protection areas. The objective of the study was to develop isopleth risk maps in effort to identify high risk areas in Mpumalanga and Limpopo Provinces. Data were collected from provincial veterinary services and World Animal Health Information Database (WAHIS) Interface for the period 2005-2015. Cattle affected by the Southern African Territories serotypes 1 and 2 of FMD Virus were selected for modelling. The proportion of affected cattle at the dip-tank level was calculated and used as the dependent variable. Data were assessed for normality by plotting histograms, calculating descriptive statistics, and performing the Anderson-Darling test for normality. Data for each serotype and a combined analysis were interpolated using ordinary kriging of reported outbreaks. Moran’s I was used to estimate the spatial autocorrelation of FMD outbreaks in cattle within the protection zone of South Africa. Data presented can assist with strengthening current FMD control measures and subsequently contribute to the development of further quantitative models.