Newsdate: Tuesday February 14, 2023 - 11:00 am
Location: BOONE, Iowa
An undervaccinated, 4-year-old Miniature Horse in St. Johns County, Florida, has been euthanized after contracting Eastern equine encephalitis (EEE). The horse presented with lethargy, inappetence, dysphagia, incoordination and hind-limb weakness on February 2.
Infectious disease transmitted by mosquito to bird to horse or human
Eastern equine encephalitis is caused by the Eastern equine encephalitis virus, for which wild birds are a natural reservoir and is transmitted by mosquitoes that feed on EEE-infected birds.
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EEE was confirmed on February 13. The horse lived in St. Johns County and has been euthanized. This is the second confirmed case of EEE in Florida for 2023.
The first confirmed case of EEE for Florida in 2023 occurred in Lake County, Florida. A 14 year-old Quarter Horse mare showed clinical signs of EEE on 1/29/2023. After the accute onset of neurologic symptoms, the mare was euthanized.
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.
EEE occurs in a wide variety of songbirds, including the blue jay, chickadee, cardinal, tufted titmouse and catbird. Mosquitoes that inhabit marshes and wooded wetlands, named Culiseta melanura,transmit the virus from bird to bird and also to horses and people.
Horses get Eastern Equine Encephalitis when they are bitten by a mosquito carrying the EEE virus. During years of outbreaks, mosquito species other than Culiseta melanura become involved in the transmission cycle. EEE cases in horses usually begin to appear in mid- to late-summer and increase in the fall.
Transmission of EEE from birds to horses usually occurs when the mosquito population is high. Horses are usually the first animals to become infected because they are normally housed in rural areas and have a greater exposure to mosquitoes.
About EDCC Health Watch
EDCC Health Watch is an Equine Network marketing program that utilizes information from the Equine Disease Communication Center (EDCC) to create and disseminate verified equine disease reports. The EDCC is an independent nonprofit organization that is supported by industry donations in order to provide open access to infectious disease information.
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