Eastern equine encephalitis virus infection in an American pygmy goat

Eastern equine encephalitis virus (EEEV; family Togaviridae, taxon species Alphavirus eastern) is a mosquito-borne alphavirus that is endemic to the Western Hemisphere and well established in freshwater hardwood swamps. EEEV is environmentally maintained through a mosquito-and-avian cycle, primarily by Culiseta melanura mosquitoes. Transmission to mammals, which are considered dead-end hosts, is well known and seasonal through C. melanura or other bridging mosquito vectors. EEE is well described in horses and humans, with relatively few reports in ruminants. Information regarding infection and disease localization, and particularly disease in the caprine species, is even more sparse. Here, we describe a case of naturally occurring EEEV infection and disease in a 4.5-y-old American pygmy goat wether with neurologic abnormalities, confirmed postmortem by reverse-transcription real-time PCR testing and indirect immunohistochemistry. The histologic alterations were confined to the CNS and were moderate-to-marked, multifocal, lymphocytic polioencephalomyelitis and meningitis, with satellitosis, neuronal necrosis, neuronophagia, and glial nodules.