New Equine EEE, WNV Cases Reported in Mass., Ill.

Officials in Massachusetts and Illinois have reported additional cases of Eastern equine encephalitis (EEE) and West Nile virus (WNV), respectively, in horses residing within their state's borders.

The Massachusetts Department of Public Health (MDPH) reported Oct. 1 that a horse residing in the town of Essex, located in the northeastern part of the commonwealth, tested positive for EEE. This most recently confirmed case is the fifth equine EEE case reported in Massachusetts this year; in 2011 Massachusetts reported just one case of equine EEE.

"Although it is October, mosquitoes continue to be present in our environment until the first hard frost," MDPH State Epidemiologist Al DeMaria, MD, said in a press release.

In Illinois, the Jackson County Health Department confirmed its third equine WNV case in late September, according to a press release from the organization. In total, six Illinois horses have tested positive this year; the state did not report any confirmed WNV cases in 2011.

According to the U.S. Geological Survey disease maps, 430 cases of equine WNV and 171 cases of EEE had been confirmed at last update (Oct. 2). The WNV case total marks the highest since 2007 when 468 cases were confirmed in horses nationwide, and the EEE total is the highest since 2010 when 247 cases were confirmed. The current total will likely rise through the end of mosquito season in warmer climates .

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 make it more difficult for the insects to 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 the 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 the stables to attract mosquitoes to areas away from horses.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.