The role of wild hosts (wild pigs and ticks) in the epidemiology of African swine fever in West Africa and Madagascar

Abstract

African swine fever (ASF) adversely affects pig production in Sub-Saharan Africa. In southern and eastern Africa, the virus is maintained in populations of wild pigs (Phacochoerus africanus) and soft ticks from the Genus Ornithodoros. The bushpig (Potamochoerus larvatus) has also been showed to be asymptomatically infected by the virus. In other parts of the African continent such as West Africa or Madagascar, the role of wild suids has not been demonstrated. The objectives of this study were to investigate the existence of a sylvatic cycle and its potential impact on the epidemiology of ASF in Senegal and Madagascar. Samples from Malagasy bushpigs and Senegalese warthogs have been collected from areas of interface between domestic and wild pigs where ASF had been reported and analyzed for anti-ASF antibodies (ELISA)and viral DNA (PCR). Ticks were collected in pig farms and near wild suids resting areas, and their infection status with ASFV was determined using PCR. In addition, sera from wild suids and domestic pigs were tested for anti-tick antibodies (ELISA). The preliminary results obtained so far suggest that the epidemiologic cycle of ASF in Senegal and Madagascar does not involve the warthog-tick-domestic pig transmission described in East and South Africa