title: Model for ranking freshwater fish farms according to their risk of infection and illustration for viral haemorrhagic septicaemia.
abstract: We developed a model to calculate a quantitative risk score for individual aquaculture sites. The score indicates the risk of the site being infected with a specific fish pathogen (viral haemorrhagic septicaemia virus (VHSV); infectious haematopoietic necrosis virus, Koi herpes virus), and is intended to be used for risk ranking sites to support surveillance for demonstration of zone or member state freedom from these pathogens. The inputs to the model include a range of quantitative and qualitative estimates of risk factors organised into five risk themes (1) Live fish and egg movements; (2) Exposure via water; (3) On-site processing; (4) Short-distance mechanical transmission; (5) Distance-independent mechanical transmission. The calculated risk score for an individual aquaculture site is a value between zero and one and is intended to indicate the risk of a site relative to the risk of other sites (thereby allowing ranking). The model was applied to evaluate 76 rainbow trout farms in 3 countries (42 from England, 32 from Italy and 2 from Switzerland) with the aim to establish their risk of being infected with VHSV. Risk scores for farms in England and Italy showed great variation, clearly enabling ranking. Scores ranged from 0.002 to 0.254 (mean score 0.080) in England and 0.011 to 0.778 (mean of 0.130) for Italy, reflecting the diversity of infection status of farms in these countries. Requirements for broader application of the model are discussed. Cost efficient farm data collection is important to realise the benefits from a risk-based approach.
authors.affiliation: Centre for Environment, Fisheries and Aquaculture Science (Cefas), Barrack Road, Weymouth, Dorset DT4 8UB, United Kingdom. Electronic address: Birgit.Oidtmann@cefas.co.uk.
authors.forename: Birgit C
authors.initials: BC
authors.lastname: Oidtmann
authors.affiliation: Centre for Environment, Fisheries and Aquaculture Science (Cefas), Barrack Road, Weymouth, Dorset DT4 8UB, United Kingdom; The Ministry for Primary Industries NZ, 25 The Terrace, Wellington 6011, New Zealand.
authors.forename: Fiona M
authors.initials: FM
authors.lastname: Pearce
authors.affiliation: Centre for Environment, Fisheries and Aquaculture Science (Cefas), Barrack Road, Weymouth, Dorset DT4 8UB, United Kingdom.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Thrush
authors.affiliation: Centre for Environment, Fisheries and Aquaculture Science (Cefas), Barrack Road, Weymouth, Dorset DT4 8UB, United Kingdom.
authors.forename: Edmund J
authors.initials: EJ
authors.lastname: Peeler
authors.affiliation: Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università, 10, 35020 Legnaro, PD, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Ceolin
authors.affiliation: Department of Production and Population Health, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield AL9 7TA, United Kingdom.
authors.forename: Katharina D C
authors.initials: KD
authors.lastname: Stärk
authors.affiliation: Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università, 10, 35020 Legnaro, PD, Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Dalla Pozza
authors.affiliation: European Food Safety Authority, Via Carlo Magno 1A, 43126 Parma, Italy.
authors.forename: Ana
authors.initials: A
authors.lastname: Afonso
authors.affiliation: Centre for Fish and Wildlife Health, Vetsuisse-Faculty, University of Bern, Länggassstrasse 122, 3001 Bern, Switzerland.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Diserens
authors.affiliation: Centre for Environment, Fisheries and Aquaculture Science (Cefas), Barrack Road, Weymouth, Dorset DT4 8UB, United Kingdom.
authors.forename: R Allan
authors.initials: RA
authors.lastname: Reese
authors.affiliation: AusVet Animal Health Services, 140 Falls Road, Wentworth Falls, 2782 NSW, Australia.
authors.forename: Angus
authors.initials: A
authors.lastname: Cameron
mesh_terms: D000818:Animals; D017756:Aquaculture; D004196:Disease Outbreaks / Q000662:veterinary*; D005060:Europe / Q000453:epidemiology; D005393:Fish Diseases / Q000453:epidemiology* / Q000635:transmission / Q000821:virology; D005399:Fishes; D031941:Hemorrhagic Septicemia, Viral / Q000453:epidemiology* / Q000635:transmission / Q000821:virology; D008962:Models, Theoretical; D029141:Novirhabdovirus / Q000502:physiology*; D011336:Probability; D018570:Risk Assessment
keywords: Disease; Disease freedom; Fish; Risk factor; Risk-based surveillance; Viral haemorrhagic septicaemia