The number of cases of Eastern equine encephalitis (EEE) in Florida has risen to 84. The cases have been found in 30 counties. Only 22 of the horses were alive at the time of reporting the disease, but according to officials, many of the horses probably did not live through the days following diagnosis. Bill Jeter, DVM, diagnostic veterinary manager for Florida's Division of Animal Industry, has said that the mortality rate in Florida EEE outbreaks is about 90%.Twenty-four of the horses began showing clinical signs in March. April and May each marked the arrival of 28 new cases. As of June 13, 4 cases have had a June date of onset.Marion County has had the most cases -- tests confirmed that 9 horses in the county had EEE. Gilchrist County has logged 8 cases, followed by Levy with 7, and Alachua and Osceola with 6 each. Other cases are sprinkled throughout counties in north central Florida.Florida had 25 EEE cases reported in 2002.Officials encourage horse owners to vaccinate for EEE, reduce mosquito populations in barn areas, and limit equine exposure to mosquitoes.According to a June 13 Associated Press story in The Post And Courier, a newspaper in Charleston, S.C., Clemson University tests show that EEE has killed four horses in Berkley County during the past several weeks.A donkey in Dorchester County and another horse in Georgetown County have tested positive for the disease. Another case has been confirmed, but details on that animal were not available.Residents believed the neurologic illness was West Nile virus (WNV) before receiving test results. The mortality rate for EEE in horses is higher than that of WNV. The Southeast is having a difficult year fighting EEE.Venaye P. Reece, DVM, Clemson University's equine programs coordinator and the state animal emergency response coordinator, was interviewed for the article. She said that EEE runs in 10-year cycles, and the last peak was in 1991. "We are due one of those spike years," she said.To learn more about EEE and other encephalitides, visit http://www.TheHorse.com.