Seroprevalence of pestivirus in four species of alpine wild ungulates in the High Valley of Susa, Italy

Wildlife, once infected, can serve as a reservoir of infectious diseases that form a constant threat to domestic livestock. To make control and eradication programs successful in the long-term, presence of pestivirus in wildlife populations should be monitored. The goal of this study was to investigate seroprevalence of pestivirus in four alpine wild ungulates in the High Valley of Susa, north-west Italy. Species studied were: red deer (Cervus elaphus), roe deer (Capreolus capreolus), wild boar (Sus scrofa) and chamois (Rupicapra rupicapra). A further goal was using virus neutralisation tests (VNT) for four strains of pestivirus in chamois and wild boar. Three hundred and seventy-five serum samples collected during the hunting season of 1999 were tested for pestivirus specific antibodies. Positive sera of chamois and wild boar were subsequently tested in a VNT with four major subtypes of pestivirus, and virus isolation was performed. No antibodies were found in the 73 samples of roe deer, while 7 (12.5%), 8 (5.9%) and 28 (25.5%) of 56, 136 and 110 samples of wild boar, red deer and chamois were ELISA-positive, respectively. Different ranges of titers were found in the VNT and no pestivirus was isolated in the ELISA-positive wild boar and chamois samples. Several possibilities, which might explain the high seroprevalence in chamois are discussed. Pestivirus antibodies were found in three out of four large alpine ungulates in the High Valley of Susa. Seroprevalence was particularly high in chamois. Further investigation is needed to characterise the pestiviruses that circulate in these animals.