title: Successful control of winter pyrexias caused by equine herpesvirus type 1 in Japanese training centers by achieving high vaccination coverage.
abstract: Equine herpesvirus type 1 (EHV-1) is a major cause of winter pyrexia in racehorses in two training centers (Ritto and Miho) in Japan. Until the epizootic period of 2008-2009, a vaccination program using a killed EHV-1 vaccine targeted only susceptible 3-year-old horses with low antibody levels to EHV-1 antigens. However, because the protective effect was not satisfactory, in 2009-2010 the vaccination program was altered to target all 3-year-old horses. To evaluate the vaccine's efficacy, we investigated the number of horses with pyrexia due to EHV-1 or equine herpesvirus type 4 (EHV-4) infection or both and examined the vaccination coverage in the 3-year-old population and in the whole population before and after changes in the program. The mean (± standard deviation [SD]) estimated numbers of horses infected with EHV-1 or EHV-4 or both, among pyretic horses from 1999-2000 to 2008-2009 were 105 ± 47 at Ritto and 66 ± 44 at Miho. Although the estimated number of infected horses did not change greatly in the first period of the current program, it decreased from the second period, with means (±SD) of 21 ± 12 at Ritto and 14 ± 15 at Miho from 2010-2011 to 2012-2013. Vaccination coverage in the 3-year-old population was 99.4% at Ritto and 99.8% at Miho in the first period, and similar values were maintained thereafter. Coverage in the whole population increased more gradually than that in the 3-year-old population. The results suggest that EHV-1 epizootics can be suppressed by maintaining high vaccination coverage, not only in the 3-year-old population but also in the whole population.
authors.affiliation: Epizootic Research Center, Equine Research Institute, Japan Racing Association, Shimotsuke, Tochigi, Japan bannai@epizoo.equinst.go.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Bannai
authors.affiliation: Racehorse Clinic, Miho Training Center, Japan Racing Association, Miho, Ibaraki, Japan.
authors.forename: Naomi
authors.initials: N
authors.lastname: Mae
authors.affiliation: Sports Science Research Center, Equine Research Institute, Japan Racing Association, Utsunomiya, Tochigi, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Ode
authors.affiliation: Epizootic Research Center, Equine Research Institute, Japan Racing Association, Shimotsuke, Tochigi, Japan.
authors.forename: Manabu
authors.initials: M
authors.lastname: Nemoto
authors.affiliation: Epizootic Research Center, Equine Research Institute, Japan Racing Association, Shimotsuke, Tochigi, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Tsujimura
authors.affiliation: Epizootic Research Center, Equine Research Institute, Japan Racing Association, Shimotsuke, Tochigi, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamanaka
authors.affiliation: Epizootic Research Center, Equine Research Institute, Japan Racing Association, Shimotsuke, Tochigi, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kondo
authors.affiliation: Epizootic Research Center, Equine Research Institute, Japan Racing Association, Shimotsuke, Tochigi, Japan.
authors.forename: Tomio
authors.initials: T
authors.lastname: Matsumura
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D005334:Fever / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary* / Q000821:virology; D006566:Herpesviridae Infections / Q000276:immunology* / Q000517:prevention & control / Q000821:virology; D004861:Herpesvirus 1, Equid / Q000276:immunology*; D023141:Herpesvirus 4, Equid / Q000276:immunology; D022283:Herpesvirus Vaccines / Q000276:immunology; D006734:Horse Diseases / Q000276:immunology* / Q000517:prevention & control / Q000821:virology; D006736:Horses; D007564:Japan; D032541:Mass Vaccination; D014611:Vaccination / Q000706:statistics & numerical data / Q000662:veterinary*; D015164:Vaccines, Inactivated / Q000276:immunology
chemical_list: D000914:Antibodies, Viral; D022283:Herpesvirus Vaccines; D015164:Vaccines, Inactivated