Eastern Equine Encephalitis
Dr. Amy Movius
Tuesday, September 29, 2009
Eastern Equine Encephalitis (EEE) is a very rare, but serious, viral disease that has killed several horses in Maine this fall. “Triple E”, as it is sometimes called, can be very dangerous and even deadly in humans as well. The Eastern Equine Encephalitis Virus (EEEV) was first seen in Maine in 2005 when it was found in some mosquitoes, birds, and horses. Then, in the fall of 2008, a man in Cumberland County died of this disease.
This fall, the EEEV has killed horses in 5 different counties of Maine. This is significant as horses are infected the same way humans are – from being bitten by an infected mosquito. The “reservoir” for EEEV is actually in songbirds. Mosquitoes, especially those found around hardwood wetlands and costal areas, can pick up the virus from birds and then infect humans (and horses). It is seen most often in late summer and early fall. Humans and horses infected with EEEV are not themselves infectious to anyone else. The increase of this disease in horses means that the virus is, unfortunately, alive and well in Maine in 2009.
Most people who become infected with EEEV will have a mild flu or no obvious illness at all. For some individuals, however, encephalitis develops. Encephalitis occurs when there is inflammation around the brain. Symptoms can include fever, headache, behavior changes and progress to coma and death. Residents of wetland areas endemic for EEEV are at risk for contracting the infection, and persons over 50 and less than 15 years of age are more prone to developing serious disease. Sadly, 1/3 of people who develop encephalitis will die and of those who survive, many have permanent brain damage.
Currently, there is no effective treatment for EEE and no vaccine for humans. The key to staying safe is prevention!
1. Always use an insect repellent when outdoors. DEET, picaridin, IR3535, and oil & lemon eucalyptus products are effective and should be applied to skin and clothes. Clothing may also be treated with permethrin, which will stay effective through several wash cycles.
2. Cover up outdoors with long sleeves/pants. Use nets to cover infant carriers.
3. *Limit or reschedule outdoor group evening activities, such as school athletic events. Participants and spectators should use insect repellents. All of these activities should end at least 1 hour before sunset if the temperature is greater than 50 degrees. This is because mosquito bites are most frequent at dusk and dawn.
4. Clean up standing water around your yard; repair any window screens that need it.
Maine is full of wetlands and mosquitoes, and this virus is expected to be a problem next year as well. We need to use and develop defensive strategies now to protect ourselves while we continue to enjoy our beautiful state.
Reference: Maine Center for Disease Control and Prevention