Abstract
African Swine Fever (ASF) is a contagious viral disease that affects all members of the family Suidae and represents a threat to the swine industry due to its potentially devastating socio-economic and political consequences. The disease is currently distributed on five continents, affecting 66 countries with different epidemiological scenarios, a range of hosts (domestic pigs and wild suids), and vectors. The lack of effective vaccine and treatment options makes it difficult to control of the disease. Therefore, knowledge of the distribution of wild suids is essential to understanding and helping predict disease infection dynamics and designing effective prevention and control strategies. In this work, we focus on the African scenario, where the ASF virus originated, it is a reservoir network with complex eco-epidemiology, and high viral diversity. In this scenario, the main host actors and vectors involved in this disease are: the common warthog (Phacochoerus africanus), considered the original vertebrate host of the ASF virus; other African wild suids (primarily bushpigs, Potamochoerus larvatus), domestic pigs and the Ornithodoros spp., the soft tick vector. To date, three cycles have been described in the endemic African setting. One is the ancient sylvatic virus cycle (where Ornithodoros ticks play a role in the maintenance of the virus, and warthogs act as seasonal amplification hosts). Another is the domestic pig-tick cycle (where the virus circulates between soft ticks associated with domestic pig sties and pigs, to the exclusion of wild suids). Lastly, the pig cycle involves a single host, the domestic pig (without the involvement of vertebrate or invertebrate sylvatic hosts). In this study, we developed a standardized distribution map based on global land cover and vegetation (GlobCover) that quantifies the quality of available habitats (QAH) for African wild suids (warthog, bushpig). Both wild suid species participate in the sylvatic cycle, contributing to the endemicity and maintenance of ASF in many countries in Africa. QAHs were estimated using a quantitative method based on expert opinion integrating spatial environmental information and epidemiological data. There was a high correlation between the QAH levels and the georeferenced presence of wild suids (n=981), the ticks’ presence (n=885), and the ASF notifications in wild suids and domestic pigs between July 2005 and June 2023 (n=517). These results suggest that the QAH map is a useful epi-tool to help predict and understand the patterns of the sylvatic cycle of ASF in the African scenario. Also, this tool could improve the management of the disease, defining risk scenarios for ASF in wild-tick-domestic pig interface, as well as for improving the prevention, control, and surveillance of ASF and other diseases that potentially affect swine and wild suids in Africa.