Laboratory transmission of eastern equine encephalomyelitis virus to chickens by chicken mites (Acari: Dermanyssidae).

Pools of adult female chicken mites, Dermanyssus gallinae (De Geer), were allowed to feed on chicks that had been inoculated with eastern equine encephalomyelitis (EEE) virus and that had a viremia level of 10(6.2)-10(6.6) plaque-forming units per milliliter of blood. Virus remained detectable by plaque assay in samples of these mites for 30 d after the infectious blood meal. Virus was not recovered from any of 151 progeny of virus-exposed female mites. Mites that had fed on viremic chicks were allowed to feed on naive chicks 3, 7, 11, 15, or 30 d later. EEE virus was transmitted to chicks by these mites on days 3 (one transmission in four trials) and 7 (one transmission in four trials). Both transmissions were confirmed by the presence of virus in chick blood 24-72 h after mites had fed, and by plaque-reduction neutralization assays of 21-d convalescent chick sera against the original viral strain.