Nationwide WNV, EEE Totals Steady as Winter Approaches

Nationwide WNV, EEE Totals Steady as Winter Approaches

Vaccinating horses against WNV and EEE coupled with mosquito control are the most important ways to minimize an animal's chances of becoming infected.

Photo: Anne M. Eberhardt/The Horse

A recent update from the USDA Animal and Plant Health Inspection Service (APHIS) indicates that the nationwide case totals of equine West Nile virus (WNV) and Eastern equine encephalitis (EEE) are beginning to steady.

According to a Dec. 12 update, 338 cases of WNV and 181 EEE cases have been reported across the country since the start of the year. In early November, the agency reported 296 WNV cases and 177 EEE in the United States since Jan. 1.

Horses in at least 40 states have been confirmed positive for WNV so far this year. The APHIS report indicates that Texas (57), Oklahoma (41), and Montana (27) have reported the most equine WNV cases thus far. According to APHIS data, Texas also led the nation in confirmed cases in 2012, with 120 reported that year, and Oklahoma confirmed 42 cases last year. Montana only confirmed six cases in 2012.

Some of the states with the most equine WNV cases in 2012 have reported decidedly fewer cases thus far in 2013. Louisiana, which reported 62 cases in 2012, has only reported four cases so far this year; Pennsylvania, which had 47 cases last year, has reported two cases since the start of the year, while Indiana has only reported a single case thus far in 2013, down from 30 last year.

Meanwhile, horses in at least 22 states have tested positive for EEE thus far in 2013, the APHIS data indicates. South Carolina (49), Florida (34), and Mississippi (12) have reported the most cases so far this year. Last year Florida reported 34 cases, South Carolina reported 14, and Mississippi had 32 cases.

As with WNV, some states are having much quieter years in 2013. Louisiana, which had the most EEE cases in 2012 with 55, has only reported eight this year. But other states are having more active EEE seasons in 2013: Georgia reported 10 cases last year but has already confirmed 24 since the start of the year, while Arkansas, which had a single case in 2012, has already reported eight this year.

Last year, a total of 627 equine WNV cases were confirmed in horses nationwide, while 209 EEE cases were reported.

Vaccinating horses against WNV and EEE coupled with mosquito control are the most important ways to minimize an animal's chances of becoming infected. In the northern regions of the United States, most veterinarians recommend vaccinating horses in the spring prior to peak mosquito levels. In the south, where mosquito populations are present year-round, veterinarians might recommend more frequent vaccination.

Minimizing mosquito populations near your horses by eliminating mosquito breeding and resting areas will reduce the chances these insects bite and infect horses and the people who care for them.

For example, reduce or eliminate sources of stagnant or standing water, remove muck from areas near the horses, stable horses during peak mosquito periods (i.e., dawn and dusk), use equine-approved mosquito repellants, place fans inside barns or stalls to maintain air movement, keep weeds and grass trimmed, and avoid using incandescent bulbs inside stables at night. Instead, place incandescent bulbs away from stables to attract mosquitoes to areas away from horses.

About the Author

Erica Larson, News Editor

Erica Larson, news editor, 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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