Alabama snakes carry dangerous pathogen
Scientists have suspected for a while that snakes are helping to transmit a deadly pathogen called Eastern equine encephalomyelitis virus (EEEV), which can infect humans. Now a team has found solid evidence: the virus’ genetic material in cottonmouth and copperhead snakes in Alabama.
Mosquitoes transmit EEEV, and the virus has been found from Florida to Michigan. To survive the winters, researchers suggested, EEEV might take refuge in animals such as snakes, which then get bitten by mosquitoes. A previous study found signs that many cottonmouths in Alabama’s Tuskegee National Forest had mounted an immune response to the virus, but it wasn’t clear whether the snakes were infected or had just been exposed.
The authors of the latest study, published in the American Journal of Tropical Medicine and Hygiene, collected blood samples from snakes in Tuskegee National Forest from spring to early fall in 2007-2009. Among cottonmouths that tested positive for antibodies to EEEV — an indication of an immune response — 22 percent contained the virus’ RNA. The team also found EEEV RNA in one copperhead. Infection rates were high in spring and lowest in mid-summer.
The results show that these snakes “have detectable infections,” the authors write. Infections might be worse during the cooler spring months because snakes can launch a stronger immune response when their body temperature is high. — Roberta Kwok | 1 October 2012
Source: Bingham, A.M. et al. 2012. Detection of Eastern equine encephalomyelitis virus RNA in North American snakes. American Journal of Tropical Medicine and Hygiene doi: 10.4269/ajtmh.2012.12-0257.
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