Florida Farm & Feed

Encephalitis kills Panhandle horses

From the Tallahassee Democrat

DEMOCRAT SENIOR WRITER
(July 03, 2001)

We thought we had problems with a drought - but a soggy June is proving troublesome as well.

State officials are urging caution for people and horses after a "mini-epidemic" of Eastern Equine Encephalitis among horses in three Panhandle counties.

Twenty-four horses in Holmes, Jackson and Santa Rosa counties (all at least 70 miles west of Tallahassee) have been diagnosed with encephalitis since June 14. As of Monday, all but one of the horses had died.

No person has been infected so far, and the danger to people is relatively low: Florida suffers an average of only one death per year from encephalitis.

But encephalitis is transmitted by mosquitoes. And after a bountiful month of rain - 9 inches above normal in June - the mosquito population of Leon County has exploded.

Which means: Make sure your horses are vaccinated and your repellent is at the ready.

"We're asking people to change their behaviors so they won't be bitten by mosquitoes," said Lisa Conti, a state public health veterinarian. "The chances of being bitten by an infected mosquito are pretty low. But we do ask that people take precautions."

Eastern equine encephalitis is a viral disease that strikes the central nervous system of horses and people. It is spread by mosquitoes that feed on infected birds. It cannot be spread from horse to horse or horse to people.

Horses are the most frequent victims, as they are always outside and available to mosquitoes. There are an estimated 350,000 horses in Florida, with about 5,000 in the affected counties of Holmes, Jackson and Santa Rosa. Leon County has an estimated 2,000 to 3,000 horses.

Though the peak months are April to August, there have been cases of horses contracting encephalitis in all 12 months of the year. The disease strikes 50 to 70 horses in Florida each year - and generally kills 90 percent of the infected horses.

Symptoms of the disease in horses include fever, impaired vision, inability to swallow, "circling" and "head pressing" against stall doors and posts.

Horses can be vaccinated against the disease, with veterinarians or owners making the intra-muscular injection in the neck or hindquarters. The normal vaccination schedule is twice a year, although Florida officials recommend three vaccinations a year because of the state's increased mosquito population.

"Once a horse begins to show clinical signs of the disease, it's almost always fatal," said William Jeter, a diagnostic veterinary manager with the state Department of Agriculture. "I'd call this a 'mini-epidemic' (in the Panhandle). But what's happened over the past two weeks is that people have started vaccinating their horses. So we're hoping the number of cases drops off dramatically."

There have been no reported cases of encephalitis in Leon County, but Tallahassee veterinarian Mike Short said his Eastgate clinic is "getting several calls a day" from horse owners.

"Our clients are definitely concerned," Short said. "If your horse has never been vaccinated, or not vaccinated in the last six months, you should call your veterinarian."

Human victims of encephalitis suffer flu-like symptoms, headaches and stiff necks. The disease can be fatal if not quickly diagnosed and controlled. The last major epidemic in Florida was in 1990, when 223 people were stricken and 11 died.

"This is not usually the time for flu-like symptoms," Conti said. "So if you feel crummy, see your physician and let him or her know if you've been bitten by a mosquito."

Mosquitoes are prevalent in Tallahassee, spawned by the 10 inches of rain dumped June 11 by the remnants of Tropical Storm Allison. Leon County Director of Mosquito Control Gene Baker said his office received 1,200 requests last week for neighborhood spraying, and his six trucks are trying to catch up with all the requests.

Baker suggested the mosquito population "may have crested" but added it would take only another significant rain event to hatch millions more mosquitoes.

"The mosquitoes biting us right now are also laying eggs for the next flood," Baker said. "Even 7 or 8 inches of rain would give us another big brood of mosquitoes."