Ten cases of Eastern equine encephalitis (EEE) and one case of West Nile virus (WNV) have been confirmed by serological testing as of April 3 in eight Florida counties, according to Leroy Coffman, DVM, Florida’s state veterinarian and director of the Division of Animal Industry. This is the first reported case of WNV in Florida this year, and possibly the first in the United States this year.

Nine of the cases of EEE--six are confirmed dead--and the case of WNV were in horses, and there has been one additional case of EEE in an emu. Six suspected equine cases of EEE are pending confirmation; only one of the six horses is alive as of this writing. The affected counties include Lake, Polk, Marion, Gilcrest, Bradford, Putnam, Suwanee, and Lafayette counties. The WNV case was confirmed in an unvaccinated 10-month-old Quarter Horse in Levy County. The horse first started showing clinical signs on March 27 and died a few days later.

The confirmed EEE cases come less than two weeks after the first case of EEE was confirmed in a 3-year-old Lake County Quarter Horse filly. The filly died the week of March 12 after being diagnosed and treated by a local veterinarian. The filly had previously been vaccinated for EEE, but had not had a booster shot in over a year, according to a press release issued by the Florida Department of Agriculture and Consumer Services (DOACS).

Coffman said that cases of EEE in Florida are typically in horses that have not been vaccinated and/or boostered. “We do get cases of West Nile virus that have been vaccinated, but as a general rule, 100% usually come back to normal--they have a better response to treatment,” he said. He recommends that Florida horses be vaccinated for EEE and WNV every four months since mosquito exposure is year-round.

Charles Bronson, commissioner of the DOACS, is emphasizing that horse owners have all horses vaccinated against EEE, as well as West Nile virus (WNV), including all booster shots. Earlier in the year, Bronson had predicted a heavier than normal mosquito season for this year.

“After nearly four years of drought, Florida has received plenty of rain during the past 18 months,” Bronson said. “And the heavy rain that the state has experienced in the last several weeks, coupled with warm, almost summer-like weather in many parts of Florida, are a prescription for a tough and early mosquito season.”

According to Coffman, EEE is a year-round disease in Florida. However, he said this latest cluster of cases is not a good sign. In 2002, Florida reported 25 cases of EEE and 499 cases of WNV in horses. “This cluster (of EEE) is not typical unless we’re going to have a bad year,” he said. “It does not bode well. It looks like the Eastern (equine encephalitis) year is starting to get rolling worse than we would have hoped. The good thing is that vaccination can help that. It certainly can have a very significant impact. People shouldn’t panic however. They should practice vigilance and take precautions.”

The Kissimmee Diagnostic State Laboratory has reported that the number of case submissions for arbovirus (viruses spread by insects) testing have increased significantly in the past few weeks.

The DOACS and Coffman recommend the following precautions beyond vaccinating horses to minimize the number of mosquitoes and the risk for mosquito-borne diseases such as EEE and WNV:

• Use insect repellants to protect against bites;
• Remove standing water such as water in old tires, pet bowls, kiddie pools, birdbaths, flower pots, etc.
• Avoid outdoor activities at dawn and dusk when mosquitoes are most active;
• Wear long sleeves and long pants when it is necessary to be out during dawn and dusk, in addition to using repellant;
• Use fans in buildings (mosquitoes are poor fliers in wind);
• Cover horses with fly sheets; and
• Feed animals away from stagnant water.

In addition, the public is asked to report dead birds to the Florida Fish and Wildlife Conservation Commission’s web site at www.wld.fwc.state.fl.us/bird.

For more information on EEE, go to the Eastern Equine Encephalitis section
For more information on WNV, go to the West Nile virus section.

About the Author

Sarah Evers Conrad

Sarah Evers Conrad has a bachelor’s of arts in journalism and equine science from Western Kentucky University. As a lifelong horse lover and equestrian, Conrad started her career at The Horse: Your Guide to Equine Health Care magazine. She has also worked for the United States Equestrian Federation as the managing editor of Equestrian magazine and director of e-communications and served as content manager/travel writer for a Caribbean travel agency. When she isn’t freelancing, Conrad spends her free time enjoying her family, reading, practicing photography, traveling, crocheting, and being around animals in her Lexington, Kentucky, home.

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