Eastern Equine Encephalitis Reported in Michigan, Summer 2020

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There has been a reported case of Easter Equine Encephalitis in Claire County.  The affected horse was an unvaccinated 2 year old filly.  In 2019, Michigan experienced the largest EEE outbreak in state history with 50 animals and 10 humans being diagnosed.  Michigan Large Animal Associates continues to advocate for proper vaccination of equine animals to reduce the risk and spread of this disease.

Eastern Equine Encephalitis can not be spread horse-to-horse or horse-to-human, it is only spread through the bite of an infected insect.  The Clinical signs develop rapidly, usually 3-5 days from infection and unvaccinated horses are especially sensitive with fatality rates are >90% .

Protection is provided through vaccination annually in the spring with a vaccine containing EEE and WEE components.  Often these are combined with tetanus and West Nile Virus.  These vaccines have proven to be very effective in preventing disease and can be boostered on a 4-6 month basis should an outbreak occur in our region.  Young or unvaccinated horses should receive a first vaccine and have a second booster vaccine 3 to 4 weeks later.  Further protection can be provided by using an equine approved insect repellent, removing sources of standing water on your property, and/or placing a fan in your horse’s stall during peak mosquito activity.

Symptoms of EEE include:


Behavior changes such as sleepiness, excitability and or aggression


Weak or staggering gait

The inability to stand

Please call our office if you think your horse is experiencing any of the above symptoms or if you want to check their vaccination status.

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