Competency of Reptiles and Amphibians for Eastern Equine Encephalitis Virus

Abstract

for technical assistance. We are also grateful to Nicole Arrigo for providing us with detailed protocols for EEEV infection and plaque assays.

Detection of Eastern Equine Encephalomyelitis Virus RNA in North American Snakes

“…9 The demonstration that wild-caught snakes contain EEEV virus in circulating blood and that the proportion of animals with circulating viremia is highest in the spring months provides further support to the hypothesis that snakes play an important role in overwintering and early season enzootic amplification of EEEV.…”

“…These data are in concordance with those of previous laboratory studies, which demonstrated that garter snakes (Thamnophis sirtalis) experimentally infected with EEEV held at low temperatures (18 C) were found to maintain circulating viremias for longer periods than did animals held at higher temperatures (25 C or 30 C). 9 It is possible this might be a consequence of the temperature dependence of the ectothermic adaptive immune system. During cooler months, snakes may not be able to raise body temperatures to levels that would enable them to clear infections because the adaptive immune response of ectotherms is more efficient at higher temperatures.…”

“…Recently, it was reported that snakes experimentally infected with EEEV developed circulating levels of viremia that were sufficient to infect mosquitoes and maintained these potentially infectious viral titers for 7-10 days. 9 This period was longer than the period that infectious titers persist in passerine birds, the accepted enzootic hosts for EEEV. Furthermore, viremic snakes, when induced to hibernate, maintained a circulating viremia upon exiting hibernation.…”

“…Furthermore, viremic snakes, when induced to hibernate, maintained a circulating viremia upon exiting hibernation. 9 Snakes also appear to be commonly exposed to EEEV. A recent serosurvey of ectothermic species from a focus of EEEV transmission in Tuskegee National Forest in Alabama showed that more than 35% of the cottonmouths (Agkistrodon piscivorus), the ectothermic species most frequently fed upon by mosquitoes in Tuskegee National Forest, 7 contained antibodies to EEEV.…”

Serosurveillance of Eastern Equine Encephalitis Virus in Amphibians and Reptiles from Alabama, USA

“…1 In addition, the prolonged viremia observed in experimentally infected reptiles relative to what is found in mammals and birds 14,15 may lead to an increased probability of transmission to mosquitoes. Scattered studies indicate that some ectothermic hosts potentially serve as competent reservoirs for arboviruses, [15][16][17][18][19][20] and support their potential role as over-wintering hosts for arboviruses. [20][21][22] Certain mosquito species appear to prefer ectothermic hosts, and some generalist species feed upon ecothermic and endothermic taxa.…”