Overwintering of Western Equine Encephalomyelitis Virus in Experimentally Infected Garter Snakes and Transmission to Mosquitoes

Abstract

Garter snakes were inoculated in September and November with Western equine encephalomyelitis (WEE) virus and were caused to hibernate under simulated natural conditions. They emerged during March, April, May, and June. After varying periods when no virus was detectable in their blood, virus was detected in concentrations as high as 106.3 > and for a period up to 70 days following emergence of snakes. Normal mosquitoes became infected by feeding on these snakes and after an extrinsic incubation period of approximately 3 weeks transmitted WEE virus to 1-day-old chicks. These data demonstrate that snakes may serve as a natural overwintering mechanism for WEE virus.