Three cases of Eastern Equine Encephalitis have been confirmed in Michigan recently and several cases of disease in horses are waiting confirmation. This raises concerns that an outbreak of the disease is beginning. EEE not only affects horses, it can also prove dangerous and even fatal to humans. "We are concerned about this finding of EEE in southwest Michigan and the likelihood of additional cases, so it's imperative people take every precaution possible to prevent mosquito borne disease exposure for themselves and their livestock," said Dr. Steven Halstead, State Veterinarian.
Eastern Equine Encephalitis (EEE) is a mosquito borne disease. The weather this year has been favorable for high populations of mosquitoes. Like West Nile virus, EEE needs a bird host as part of the disease cycle. A mosquito bites an infected bird, then bites a horse or human and transmits the disease. Humans and horses cannot get EEE directly from each other. Many species of wild birds in Michigan are infected with EEE. Most birds are little affected by the disease and become carriers or reservoirs of the disease.
In horses the disease is often fatal or horses have to be destroyed when they suffer from lingering neurological problems. They suffer from incoordination, poor appetite, high fever, depression and disorientation, which may also progress to brain damage and paralysis. There is a vaccine for EEE that can be given to horses and if your horses have not been vaccinated this year you should have it done immediately. If horses get the disease supportive care is all that can be done. Some horses can recover fully from EEE.
In humans EEE may begin with flu like symptoms, fever, headache, muscle pains. That can be the extent of the disease or in some cases the disease progresses to encephalitis, brain swelling, paralysis, and severe neurological damage. Many people will not know they have had EEE. The disease is more likely to be severe in young children and those over 60 or those with compromised immune systems. When the disease progresses to neurological symptoms, the mortality rate is about 33%. Many of the survivors are left with brain damage or severe neurological disabilities.
There is no vaccine to prevent EEE in humans. Michigan Department of Community Health director Janet Olszewski had this to say about the outbreak. "Michigan residents need to know the risks associated with mosquito-borne illnesses, which is why we are encouraging citizens to observe several common sense steps to limit exposure to mosquitoes. One bite from an infected mosquito can lead to a severe - and possibly life-altering - illness. Prevention is the key to protection."
All Michigan residents should wear mosquito repellants when outdoors, and fix screens and doors so mosquitoes are less likely to enter homes. Keep vegetation trimmed around the home. Avoid swampy areas and being outside at dawn and dusk- peak mosquito times. Wear long sleeves and pants if you are in mosquito dense areas. Strong air currents repel mosquitoes and a briskly blowing fan could be used to protect babies too young for repellants on the patio or deck.
Mosquitoes need water to breed, so empty all standing water in trash, flower saucers, birdbaths, animal water containers, and un-chlorinated kiddy pools at least twice a week. Clean plugged gutters and treat ornamental ponds without fish with BT, a naturally occurring disease organism that kills mosquito larvae. It is harmless to people and pets and the briquettes containing it are sold in garden stores. If you have large animal tanks that are seldom emptied add a few tiny goldfish to them. They will eat mosquito larvae. BT briquettes could also be used.
Horses should be vaccinated for EEE yearly. The vaccination for West Nile Virus does not protect against EEE. Its important to get both vaccines, because West Nile can be deadly too. Horses should be treated with insect repellants approved for horses. Unvaccinated horses should be kept inside from dusk until full daylight, or on cloudy, misty days, preferably in a screened stable. Drain standing water from pastures and avoid pasturing horses near swamps or untreated ponds. Keep wild birds out of stables and barns.
Cases of EEE in other animals have been documented but the disease is very rare in species other than birds, horses and humans. All livestock and pets should be treated with animal approved insect repellants when outdoors to lessen the risk.
For more information on the human health impact of EEE, please visit the Centers for Disease Control and Prevention (CDC) web site at:
www.cdc.gov/ncidod/dvbid/arbor/eeefact.htm.
For more information about EEE in horses, consult your local veterinarian or contact MDA's Animal Industry Division at 517-373-1077; or visit the MDA website at: www.michigan.gov/mda.
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