title: Persistence of infectious pancreatic necrosis virus (IPNV) in Scottish salmon (Salmo salar L.) farms.
abstract: Infectious pancreatic necrosis is a disease that is causing increasing loses to Scottish Atlantic-salmon farms. I asked the question: is infection of individual salmon farms persistent or transient? Using Fisheries Research Services' Fish Health Inspectors' data, conditional probabilities that a farm would (time 0) be infected were estimated for farms that had been infected [P(I(0)|I(-T))] or free [P(I(0)|F(-T))] from infectious pancreatic necrosis virus (IPNV) when a sample was taken at some earlier time (-T). A logistic-regression model was used to estimate these conditional probabilities with T; this model was multilevel to account for regional and inter-annual level differences in prevalence of IPNV. In freshwater, conditional probabilities remained substantially different for periods of at least 4 years, so, although many farms did change infection status, IPNV either persisted or recurred at specific freshwater farms. Marine farms showed similar conditional probabilities after about 2 years following a positive or a negative sample, indicating that infection was transient. Management of larger areas and exchanges between farms might be more effective than farm-level management at controlling marine IPNV.
authors.affiliation: Fisheries Research Services Marine Laboratory, Victoria Road, Aberdeen AB11 9DB, United Kingdom. murrays@marlab.ac.uk
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Murray
mesh_terms: D000818:Animals; D017756:Aquaculture; D018175:Birnaviridae Infections / Q000453:epidemiology / Q000662:veterinary*; D005393:Fish Diseases / Q000453:epidemiology*; D005618:Fresh Water; D018061:Infectious pancreatic necrosis virus / Q000472:pathogenicity*; D016015:Logistic Models; D015995:Prevalence; D020317:Salmo salar; D012606:Scotland / Q000453:epidemiology; D012623:Seawater