USDA Tracking Equine EEE, WNV Case Numbers

The USDA/APHIS is keeping a running tally of the number of confirmed cases of WNV, EEE, and WEE in the U.S.

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As most parts of the nation are in the midst of the mosquito-borne disease season, the USDA Animal and Plant Health Inspection Service (APHIS) is keeping a running tally of the number of confirmed cases of West Nile virus (WNV), Eastern equine encephalitis (EEE), and Western equine encephalitis (WEE) reported within the United States.

In the tally, which was last updated Sept. 16, APHIS’ National Animal Health Surveillance System (NAHSS) reports that 28 cases of WNV have been confirmed in the U.S. in 2011. Leading the way in case counts are California and Pennsylvania, both of which have five confirmed cases in 2011. Arizona, Indiana, and Texas have all reported two cases of WNV thus far, and one case has been reported in Florida, Georgia, Iowa, Kentucky, Massachusetts, Minnesota, Mississippi, Nevada, New York, Oregon, Virginia, and Wisconsin.

In 2010 NAHSS reported 125 confirmed WNV cases in 28 states. Clinical signs of WNV include flulike conditions where the horse seems mildly anorexic and depressed; fine and coarse muscle and skin fasciculations (twitching); hyperesthesia, or hypersensitivity to touch and sound; changes in mentation (mentality), when horses look like they are daydreaming or "just not with it"; occasional somnolence (drowsiness); propulsive walking (driving or pushing forward, often without control); and "spinal" signs, including asymmetrical weakness. Some horses show asymmetrical or symmetrical ataxia (incoordination on one or both sides, respectively). Equine mortality rate can be as high as 30-40%.

As of Sept. 16, NAHSS reported 23 cases of EEE since the beginning of the year. Nine cases have been confirmed in New York so far, followed by three in Florida and Louisiana. One EEE case has been reported in each of the following states: Minnesota, Mississippi, and North Carolina. At the time of the last NAHSS update, only five cases of EEE had been reported in Wisconsin. However the number of confirmed cases has since risen to 25, bringing the national total thus far to 43 cases

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Written by:

Erica Larson, former news editor for The Horse, holds a degree in journalism with an external specialty in equine science from Michigan State University in East Lansing. A Massachusetts native, she grew up in the saddle and has dabbled in a variety of disciplines including foxhunting, saddle seat, and mounted games. Currently, Erica competes in eventing with her OTTB, Dorado.

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