title: Evaluating the risk of pathogen transmission from wild animals to domestic pigs in Australia.
abstract: Wild animals contribute to endemic infection in livestock as well as the introduction, reintroduction and maintenance of pathogens. The source of introduction of endemic diseases to a piggery is often unknown and the extent of wildlife contribution to such local spread is largely unexplored. The aim of the current study was to quantitatively assess the probability of domestic pigs being exposed to different pathogens from wild animals commonly found around commercial piggeries in Australia. Specifically, this study aims to quantify the probability of exposure to the pathogens Escherichia coli, Salmonella spp. and Campylobacter spp. from European starlings (Sturnus vulgarus); Brachyspira hyodysenteriae, Lawsonia intracellularis and Salmonella spp. from rats (Rattus rattus and Rattus norvegicus); and Mycoplasma hyopneumoniae, Leptospira spp., Brucella suis and L. intracellularis from feral pigs (Sus scrofa). Exposure assessments, using scenario trees and Monte Carlo stochastic simulation modelling, were conducted to identify potential pathways of introduction and calculate the probabilities of these pathways occurring. Input parameters were estimated from a national postal survey of commercial pork producers and from disease detection studies conducted for European starlings, rats and feral pigs in close proximity to commercial piggeries in Australia. Based on the results of the exposure assessments, rats presented the highest probability of exposure of pathogens to domestic pigs at any point in time, and L. intracellularis (median 0.13, 5% and 95%, 0.05-0.23) and B. hyodysenteriae (median 0.10, 0.05-0.19) were the most likely pathogens to be transmitted. Regarding European starlings, the median probability of exposure of domestic pigs to pathogenic E. coli at any point in time was estimated to be 0.03 (0.02-0.04). The highest probability of domestic pig exposure to feral pig pathogens at any point in time was found to be for M. hyopneumoniae (median 0.013, 0.007-0.022) and L. intracellularis (median 0.006, 0.003-0.011) for pigs in free-range piggeries. The sensitivity analysis indicates that the presence and number of wild animals around piggeries, their access to piggeries and pig food and water, and, in the case of feral pigs, their proximity to piggeries, are the most influential parameters on the probability of exposure. Findings from this study support identification of mitigation strategies that could be implemented at on-farm and industry level to minimize the exposure risk from European starlings, rats and feral pigs.
authors.affiliation: University of Sydney, Faculty of Veterinary Science, 425 Werombi Rd, Camden, New South Wales 2570, Australia; Invasive Animal Cooperative Research Centre, University of Canberra, ACT 2601, Australia. Electronic address: hayley.e.pearson@gmail.com.
authors.forename: Hayley E
authors.initials: HE
authors.lastname: Pearson
authors.affiliation: University of Sydney, Faculty of Veterinary Science, 425 Werombi Rd, Camden, New South Wales 2570, Australia.
authors.forename: Jenny-Ann L M L
authors.initials: JLML
authors.lastname: Toribio
authors.affiliation: Invasive Animal Cooperative Research Centre, University of Canberra, ACT 2601, Australia; South Australian Research and Development Institute, Plant Research Centre, Waite Campus, 2b Hartley Grove, Urrbrae, South Australia 5064, Australia.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Lapidge
authors.affiliation: Graham Centre for Agricultural Research (NSW Department of Primary Industries and Charles Sturt University), School of Animal and Veterinary Sciences, Booroma Street, Wagga Wagga, New South Wales 2678, Australia.
authors.forename: Marta
authors.initials: M
authors.lastname: Hernández-Jover
mesh_terms: D000818:Animals; D000835:Animals, Wild; D001315:Australia / Q000453:epidemiology; D001715:Bird Diseases / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission; D051381:Rats; D012307:Risk Factors; D012376:Rodent Diseases / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission; D020308:Songbirds; D034421:Sus scrofa; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission
keywords: European starling; Exposure; Feral pig; Livestock; Pathogen; Rat