Possible overwintering reservoirs and experimental epidemiology of western equine encephalitis virus

The experimental and field evidence presented in this thesis relative to the possibility that snakes are important in the over-wintering mechanism of WEE virus in nature are as follows: 1. Virus titers in snakes were found to be sufficiently high to infect a significant percentage of mosquitoes feeding on them. The ID50 for a mosquito was found to be approximately 10(5.2)PFU/ml. 2. The duration of viremia in these animals was considerably longer, even at room temperature, than has been found in most other animals. 3. Under the conditions of the experiments, two infective mosquitoes were sufficient to infect certain snakes. 4. Virus was isolated from at least one snake captured in nature during the spring, when recent infection by C. tarsalis was impossible. 5. Possible evidence for a cycling phenomena of WEE virus in the blood of snakes kept at room temperature was discussed. In preliminary studies involving experimental infection of bats with WEE virus it was not found that under hibernating conditions, one species of bat, P. townsendii, would maintain WEE virus in the circulating blood for at least 36 days and in tissues for a least 45 days.