Wisconsin Ag Connection - West Nile Virus Detected in Ruffed Grouse

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West Nile Virus Detected in Ruffed Grouse
Wisconsin Ag Connection - 01/17/2019

West Nile virus was detected in three of 16 ruffed grouse that were found sick or dead and submitted by the public to the Wisconsin Department of Natural Resource for testing this past fall.

The agency says there is no evidence to confirm that WNV or any other factor is having population-level impacts on ruffed grouse in Wisconsin. Ruffed grouse populations are known to rise and fall over a nine- to 11-year cycle, so declines are not unexpected, though the 2017 decline occurred before the cycle would typically predict.

Of these 16 birds, ten were negative for any viral infection, three were positive for Eastern Equine Encephalitis virus, one was positive for WNV and two were positive for both EEEV and WNV. Of the six birds that tested positive for EEEV or WNV, three showed signs of clinical disease, which may or may not have eventually resulted in death.

These results are preliminary, and 238 hunter-harvested grouse samples remain to be tested from the first year of a three-year study of WNV in ruffed grouse across Wisconsin, Minnesota and Michigan.

Both WNV and EEEV are mosquito-borne viruses that can affect humans, horses and certain species of birds.

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