High case-rate equine herpesvirus-1 abortion outbreak in vaccinated polo mares in Argentina.

摘要

An extensive, high case-rate outbreak of abortion due to equine herpesvirus 1 (EHV-1) that occurred during the 1998 foaling season among 4 groups of vaccinated mares on 2 polo breeding farms and an adjacent equine reproductive centre (ERC) located in the province of Buenos Aires, Argentina, is described. A total of 173 pregnant mares were located on the 3 affected premises. Tissues were collected from 2 aborted fetuses within each of the 4 mare groups for virus isolation. Serum samples were collected from 76 mares from 3 groups to determine the level of EHV1 neutralizing antibodies. Of the 173 mares, 50 (28%) lost their foals as a result of EHV1 infection. A virus exhibiting cytopathic effects typical for a herpesvirus was isolated from tissues ofall examined aborted fetuses. Each of the isolates was identified as EHV 1 by monoclonal antibody serotyping. Serum virus-neutralizing antibody titres in the 76 mares tested ranged from 1:32 to 1:512. Broodmare management and immunization strategies designed to prevent or minimize the likelihood of exposure to EHV 1 and to maximize the mare's immune status to the herpesvirus have been recommended to the affected premises for future breeding and foaling seasons.