title: Estimating the incidence of equine viral arteritis and the sensitivity of its surveillance in the French breeding stock.
abstract: Equine viral arteritis (EVA) may have serious economic impact on the equine industry. For this reason, it is monitored in many countries, especially in breeding stock, to avoid its spread during breeding activities. In France, surveillance is mainly based on serological tests, since mares are not vaccinated, but difficulties in interpreting certain series of results may impair the estimation of the number of outbreaks. In this study, we propose specific rules for identifying seroconversion in order to estimate the number of outbreaks that were detected by the breeding stock surveillance component (BSSC) in France between 2006 and 2013. A consensus among multidisciplinary experts was reached to consider seroconversion as a change in antibody titer from negative to at least 32, or as an eight-fold or greater increase in antibody level. Using these rules, 239 cases and 177 outbreaks were identified. Subsequently, we calculated the BSSC's sensitivity as the ratio of the number of detected outbreaks to the total number of outbreaks that occurred in breeding stock (including unreported outbreaks) estimated using a capture-recapture model. The total number of outbreaks was estimated at 215 (95% credible interval 195-249) and the surveillance sensitivity at 82% (CrI95% 71-91). Our results confirm EVA circulation in French breeding stock, show that neutralizing antibodies can persist up to eight years in naturally infected mares and suggest that certain mares have been reinfected. This study shows that the sensitivity of the BSSC is relatively high and supports its relevance to prevent the disease spreading through mating.
authors.affiliation: National Institute for Agricultural Research (INRA), UR0346 Animal Epidemiology, F-63122 Saint-Genès-Champanelle, France; French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Dozulé Laboratory for Equine Diseases, Epidemiology and Pathological Anatomy Unit, F-14430 Goustranville, France. Electronic address: jean-philippe.amat@anses.fr.
authors.forename: J P
authors.initials: JP
authors.lastname: Amat
authors.affiliation: Royal Veterinary College, Veterinary Epidemiology, Economics and Public Health Group, Hawkshead Lane, North Mymms, Hatfield AL9 7TA, London, United Kingdom. Electronic address: tvergne@rvc.ac.uk.
authors.forename: T
authors.initials: T
authors.lastname: Vergne
authors.affiliation: French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Dozulé Laboratory for Equine Diseases, Epidemiology and Pathological Anatomy Unit, F-14430 Goustranville, France. Electronic address: jackie.tapprest@anses.fr.
authors.forename: J
authors.initials: J
authors.lastname: Tapprest
authors.affiliation: French institute for horse and riding (IFCE), F-27310 Saint-Ouen-de-Thouberville, France. Electronic address: benedicte.ferry@ifce.fr.
authors.forename: B
authors.initials: B
authors.lastname: Ferry
authors.affiliation: ANSES, Dozulé Laboratory for Equine Diseases, Virology Unit, F-14430 Goustranville, France. Electronic address: aymeric.hans@anses.fr.
authors.forename: A
authors.initials: A
authors.lastname: Hans
authors.affiliation: ANSES, Laboratory Affairs Department, 31 Avenue Tony Garnier, F-69007 Lyon, France. Electronic address: pascal.hendrikx@anses.fr.
authors.forename: P
authors.initials: P
authors.lastname: Hendrikx
authors.affiliation: Veterinary School of Maisons-Alfort (ENVA), EpiMAI Unit ENVA-joint ANSES, 7 Avenue du Général de Gaulle, F-94704 Maisons-Alfort, France. Electronic address: bdufour@vet-alfort.fr.
authors.forename: B
authors.initials: B
authors.lastname: Dufour
authors.affiliation: National Institute for Agricultural Research (INRA), UR0346 Animal Epidemiology, F-63122 Saint-Genès-Champanelle, France. Electronic address: agnes.leblond@vetagro-sup.fr.
authors.forename: A
authors.initials: A
authors.lastname: Leblond
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D018174:Arterivirus Infections / Q000097:blood / Q000453:epidemiology / Q000662:veterinary*; D004196:Disease Outbreaks; D007240:Equartevirus; D005260:Female; D005602:France / Q000453:epidemiology; D006734:Horse Diseases / Q000097:blood / Q000453:epidemiology / Q000821:virology*; D006736:Horses; D009500:Neutralization Tests; D016036:Seroepidemiologic Studies
chemical_list: D000914:Antibodies, Viral
keywords: Bayesian inference; Breeding stock; Capture-recapture; Epidemiology; Equine viral arteritis; Seroconversion; Surveillance; Surveillance sensitivity