Protect Yourself from Eastern Equine Encephalitis (EEE): A Guide to Prevention and Awareness

What is EEE or Eastern Equine Encephalitis?

Eastern Equine Encephalitis (EEE) is a rare but lethal mosquito-borne illness that has gained significant attention due to its severe impact on human health, including the recent death of a healthy 41-year old New Hampshire man. With mortality rates ranging from 30-60%, and survivors often facing significant neurological damage, EEE is the most dangerous of the arboviruses transmitted by mosquitoes in the U.S. to humans, horses, and other animals. Permethrin-treated clothing is an effective method of staying protected.

Eastern Equine Encephalitis (EEE) is a rare and lethal mosquito-borne illness

EEE Impact to Humans and Animals

EEE is primarily maintained in a cycle involving Culiseta melanura mosquitoes, which feed on birds in freshwater hardwood swamps. For humans to contract the virus, specific mosquito species like Aedes, Coquillettidia, and Culex—some of which are common in many parts of the U.S.—need to act as "bridge" vectors, transmitting the virus from infected birds to mammals, including humans and horses.

As residential areas expand into previously undeveloped swamp regions, the likelihood of human contact with these bridge vectors increases. Joe Conlon, Technical Advisor of the American Mosquito Control Association, explains, “As humans continue to move into hardwood swamps, they will come into increased contact with the bridge vectors and potential disease transmission.” He further emphasizes the importance of protection, “Fortunately, there are generally very few cases countrywide yearly; however, it only takes one case and one fatality to remind us that we must protect ourselves.”

Which Mosquitoes Can Transmit EEE?

When compared to other diseases such as West Nile and others, EEE is far less prevalent yet more lethal and potentially incurable. Certain mosquitoes, such as Aedes vexans, one of the most numerous human-biters, lay eggs in ground depressions that can remain viable for years, awaiting rains. Coquillettidia perturbans, which breeds in among cattail swamps is another vector, while Ochlerotatus canadensis, a woodland swamp breeder and Oc. sollicitans, which breeds in saltmarshes, also serve as vectors.

What are the Signs and Symptoms of EEE?

Symptoms of EEE generally occur a few days or up to two weeks after infection. Symptoms can include:

High fever
Headache
Tiredness
Nausea/vomiting
Neck stiffness

According to Boston Children’s Hospital, the symptoms of encephalitis depend on the part of the brain that is inflamed, the amount of inflammation and the person’s age and overall health.

Some of the most common symptoms of encephalitis include:

Seizures
Confusion (disorientation)
Coma

In one-third of cases, encephalitis can be fatal or lead to permanent brain damage.

How to Prevent Getting EEE?

Due to the lack of available treatments for EEE, prevention is essential. The best way to avoid contracting the virus is to prevent mosquito bites. If you avoid being bitten by an infected mosquito, you cannot contract EEE.

Here are some effective preventive measures:

Wear Permethrin-Treated Clothing: Clothing treated with permethrin can help prevent bites from mosquitoes, including those that may carry EEE.
Use Topical Insect Repellents: Always have repellents available when spending time outdoors, especially in areas known for mosquito activity.
Eliminate Standing Water: Mosquitoes breed in standing water, so it’s important to fill in or drain low areas like puddles or ruts in your yard. Ensure that drains, ditches, and culverts are free of debris to facilitate proper drainage.
Maintain Your Yard: Keep grass short and shrubs trimmed to minimize mosquito hiding places. Installing bird or bat houses can also help reduce mosquito populations, as these animals feed on insects.

For more detailed information, refer to the CDC’s Information Page on preventing mosquito bites. Staying informed and taking proactive steps can greatly reduce the risk of EEE and other mosquito-borne diseases.