To test the hypothesis that hibernating colonial bats serve as an overwintering reservoir host of eastern equine encephalomyelitis (EEE) and certain other arthropod-borne viruses in southern New England, 1128 bats of 4 species were collected from 1966 through 1976. Blood and tissue samples and ectoparasites from these bats were tested in suckling mice, wet chicks, and/or chick-embryo tissue cultures for virus. Rabies, the only virus isolated, was recovered from the brain, salivary glands, and brown fat of an apparently healthy adult male Myotis keenii found hibernating in western Massachusetts.
EEE neutralizing antibody was detected in 1.3% of the adult bats tested. A significant difference was noted between prevalence of antibody in hibernating (0.3%) and nonhibernating (3.4%) bats tested during the first 4 years of this study. One of 26 (3.8%) sera neutralized California encephalitis virus and no neutralizing or hemagglutination-inhibition antibody was detected with western equine encephalomyelitis virus.