title: Eastern equine encephalitis virus: high seroprevalence in horses from Southern Quebec, Canada, 2012.
abstract: Eastern equine encephalitis virus (EEEV) is a highly pathogenic arbovirus that infects humans, horses, and other animals. There has been a significant increase in EEEV activity in southeastern Canada since 2008. Few data are available regarding nonlethal EEEV infections in mammals, and consequently the distribution and pathogenicity spectrum of EEEV infections in these hosts is poorly understood. This cross-sectional study focuses on the evaluation of viral activity in southern Quebec's horses by seroprevalence estimation. A total of 196 horses, 18 months and older, which had never been vaccinated against EEEV and have never traveled outside Canada, were sampled from 92 barns distributed throughout three administrative regions of southern Quebec. Blood samples were taken from each horse and titrated for EEEV antibodies by plaque reduction neutralization test (PRNT). Equine population vaccination coverage was estimated by surveying horse owners and equine practitioners. PRNT results revealed an EEEV seroprevalence up to 8.7%, with 95% confidence limits ranging from 4.4% to 13.0%. Vaccination coverage was estimated to be at least 79%. Our study reveals for the first time in Canada a measure of EEEV seroprevalence in horses. High seroprevalence in unvaccinated animals challenges the perception that EEEV is a highly lethal pathogen in horses. Monitoring high-risk vector-borne infections such as EEEV in animal populations can be an important element of a public health surveillance strategy, population risk assessment and early detection of epidemics.
authors.affiliation: 1 Groupe de recherche en épidémiologie des zoonoses et santé publique, Faculté de médecine vétérinaire, Université de Montréal , Saint-Hyacinthe, Québec, Canada .
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Rocheleau
authors.forename: Julie
authors.initials: J
authors.lastname: Arsenault
authors.forename: L Robbin
authors.initials: LR
authors.lastname: Lindsay
authors.forename: Antonia
authors.initials: A
authors.lastname: DiBernardo
authors.forename: Manisha A
authors.initials: MA
authors.lastname: Kulkarni
authors.forename: Nathalie
authors.initials: N
authors.lastname: Côté
authors.forename: Pascal
authors.initials: P
authors.lastname: Michel
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D003430:Cross-Sectional Studies; D004663:Encephalitis Virus, Eastern Equine / Q000276:immunology / Q000302:isolation & purification*; D004683:Encephalomyelitis, Equine / Q000453:epidemiology* / Q000821:virology; D005240:Feasibility Studies; D005843:Geography; D006734:Horse Diseases / Q000453:epidemiology* / Q000821:virology; D006736:Horses; D006801:Humans; D062486:Public Health Surveillance; D011792:Quebec / Q000453:epidemiology; D016036:Seroepidemiologic Studies; D014611:Vaccination; D015047:Zoonoses
chemical_list: D000914:Antibodies, Viral