The number of Eastern equine encephalitis (EEE) cases in Florida had risen to 70 as of May 30, further substantiating an earlier suspicion that 2003 will be a tough year for fighting the disease. Florida’s case count for all of 2002 was 25 horses.

The disease is caused by a virus found in wild birds, and it’s transmitted to horses and humans via the bite of an infected mosquito. Horses do not develop high enough levels of the virus in their blood to be contagious to other humans or animals.

Vaccination histories are unknown for at least 28 of the 70 cases, and at least 31 had not been vaccinated for EEE within the past six months or at all. Sixteen of the 70 horses were recovering when the cases were logged; the other 54 horses died or were euthanized. According to Bill Jeter, DVM, diagnostic veterinary manager for Florida’s Division of Animal Industry, “The sixteen cases that were reported were alive at the time the horses were seen by the veterinarians, and if we do a follow-up on these cases, I am sure that some of them would not have survived, as the horses would have died or have been euthanized a day or two later.” A 90% mortality rate is associated with EEE in Florida.

The counties hit hardest are in the north central part of the state, including: Alachua (five cases), Bradford (four), Gilchrist (eight), Levy (seven), Marion (eight), Osceola (six), and Union (four). Most of the cases in Florida have had April onset dates (28), closely followed by March (24). Eighteen of the horses began showing clinical signs of EEE in May