Supplementary feeding as a source of multiresistant Salmonella in endangered Egyptian vultures

Wild birds have repeatedly been highlighted as vectors in the dissemination of livestock and human pathogens. Here, the occurrence, serotypes and antimicrobial resistance of Salmonella were assessed in adult Egyptian vultures (Neophron percnopterus), to test the hypothesis that infection is associated with the consumption of swine carcasses provided at supplementary feeding stations (SFSs). Faeces of year-round resident griffon vultures (Gyps fulvus) were also tested to assess whether infection was acquired in the breeding grounds of both species or in the African wintering quarters of Egyptian vultures. Depending on the shedding rate criteria considered, the occurrence of infection in Egyptian vultures varied between the three consecutive sampling days in a range with a minimum of 23%-41% and a maximum of 64%-92% of individuals (n = 11-14 individuals, 27-39 faeces). The occurrence in the single sampling of griffon vultures was 61% of faeces (n = 18). Vultures mostly fed on pig carcasses, which together with their predominant infection with multiresistant serotypes (mostly the monophasic 4,12:i:- variant resistant to aminopenicillins, aminoglycosides and tetracyclines) typically found in pigs from Spain, strongly supports a carcass-to-vulture transmission and cross-infection routes at SFSs. Efforts are encouraged to avoid discarding carcasses of pigs with Salmonella at SFSs established for the conservation of threatened scavengers. This could contribute to reducing the long-distance transmission of resistant pathogens with an impact on livestock and human health while avoiding infection risk and its effects on wildlife.