25 Confirmed Cases of EEE in Florida Counties

Rachel Lacey, DVM, equine programs manager for the Florida Department of Agriculture and Consumer Services, confirmed on Aug. 12 that 25 Florida equids have tested positive this year for Eastern equine encephalomyelitis (EEE). The number is within the “normal” range, she said. In 2018 Florida officials confirmed 64 cases.

Officials have not confirmed several suspected cases due to the veterinarians’ or owners’ inability to obtain a blood serum or brain tissue sample for laboratory polymerase chain reaction (PCR) testing.

“The American Association of Equine Practitioners recommends vaccinating for EEE every four to six months in high-risk areas such as Florida,” Lacey said. “The vaccine is very effective if given properly. There are many elements to consider when choosing a vaccination protocol for your horse, such as the age and overall health of the individual and environmental and circumstantial risk factors. This is why we highly recommend that owners work closely with their veterinarians to determine the plan that best suits their needs.”

Eastern equine encephalomyelitis is caused by the Eastern equine encephalitis virus, for which wild birds are a natural reservoir. Mosquitoes that feed on EEE-infected birds can transmit the virus to humans, horses, and other birds. Horses do not develop high enough levels of these viruses in their blood to be contagious to other animals or humans. Because of the high mortality rate in horses and humans, EEE is regarded as one of the most serious mosquito-borne diseases in the United States.

Tips for preventing mosquito-borne diseases include:

  • Avoid mosquito bites: Use insect repellent when outdoors, especially from dusk to dawn.
  • Look for EPA-labeled products containing active ingredients such as DEET, picaridin (KBR3023), or oil of lemon eucalyptus (p-menthane 3,8-diol).
  • Apply more repellent, according to label instructions, if mosquitoes start to bite.
  • Mosquito-proof homes: Fix or install window and door screens, and cover or eliminate empty containers with standing water where mosquitoes can lay eggs.
  • Protect your horses: Veterinarians recommend commercially available licensed vaccines against EEE for all horses in the U.S. Horses should be vaccinated at least annually (recommendations vary in high-risk areas). It’s not too late this year to vaccinate your horses.
  • Use approved insect repellents to protect horses.
  • If possible, put horses in stables, stalls, or barns during the prime mosquito exposure hours of dusk and dawn.
  • Eliminate standing water, drain water troughs, and empty buckets at least weekly.
  • Stock water tanks with fish that consume mosquito larvae (contact your local mosquito control for assistance), or use mosquito “dunks” (solid “donuts” of Bacillus thuringiensis israelensis [BTi], which are nontoxic to horses) available at hardware stores.