Understanding Eastern Equine Encephalitis: A Rare but Deadly Mosquito-Borne Disease

Eastern equine encephalitis (EEE) may not be a household name, but this rare viral disease, transmitted by mosquitoes, is one of the most severe and dangerous illnesses you can contract from a bug bite. With its high mortality rate and the potential for devastating neurological damage, EEE is a public health concern that deserves your attention, especially if you live in or near affected regions.

What Is Eastern Equine Encephalitis?

Eastern equine encephalitis, or EEE, is a disease caused by the Eastern equine encephalitis virus (EEEV). The virus is primarily found in the eastern United States, Gulf Coast states, and some parts of the Caribbean, Central America, and South America. It infects both humans and animals, particularly horses—hence the name.

The disease is transmitted through the bite of an infected mosquito. The mosquitoes that carry the virus typically feed on birds, which serve as natural reservoirs for EEEV. However, when these mosquitoes bite mammals like horses or humans, they can transmit the virus, leading to infection.

Transmission Cycle of Eastern Equine Encephalitis Virus (EEEV)
https://www.nejm.org/doi/full/10.1056/NEJMp1914328#f1

The Impact of EEE on Humans

While EEE is rare, it is extremely dangerous. The symptoms typically start within 4 to 10 days after a person is bitten by an infected mosquito. Early signs include fever, chills, headache, and vomiting—symptoms that can be mistaken for the flu. However, as the disease progresses, it can lead to severe neurological symptoms like disorientation, seizures, and coma, due to encephalitis, which is the swelling of the brain.

Unfortunately, EEE is one of the deadliest mosquito-borne diseases in the United States, with a mortality rate of about 30-50% in those who develop encephalitis. Even among survivors, many are left with permanent neurological damage, which can include intellectual impairment, personality changes, seizures, paralysis, and cranial nerve dysfunction.

EEE in Horses

EEE is also a significant concern for horse owners. Horses infected with EEE often display symptoms similar to those seen in humans, such as fever, depression, lack of coordination, and severe neurological issues. Sadly, EEE is nearly always fatal in horses, with most animals succumbing to the illness within a few days of showing symptoms.

Prevention Is Key

There is currently no specific treatment for EEE in humans or animals. This makes prevention crucial. The best way to protect yourself and your loved ones from EEE is to avoid mosquito bites, especially in areas where the virus is known to circulate.

Here are some practical steps you can take:

• Use Insect Repellent: Apply EPA-approved insect repellent that contains ingredients like DEET, picaridin, or oil of lemon eucalyptus when outdoors.

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• Wear Protective Clothing: Long sleeves, pants, and socks can help prevent mosquito bites, particularly during peak mosquito activity times, which are dawn and dusk.

• Secure Your Home: Use screens on windows and doors and consider using air conditioning instead of leaving windows open.

• Eliminate Standing Water: Mosquitoes lay their eggs in standing water, so regularly empty and clean items that collect water, such as bird baths, flower pots, and gutters.

For horse owners, vaccination is the most effective way to prevent EEE. Annual vaccination is recommended, especially in regions where EEE is common. Talk to your veterinarian about the best vaccination schedule for your horses.

Conclusion

Eastern equine encephalitis is a rare but extremely serious disease that can have devastating consequences for both humans and animals. While it may be rare, the high mortality rate and potential for severe neurological damage make it a disease you can’t afford to ignore.

As we continue to enjoy the great outdoors, especially during mosquito season, it’s important to stay informed and take preventive measures to protect yourself, your family, and your animals from EEE. Remember, a single mosquito bite could change everything, so be vigilant and take the necessary precautions.

Stay safe and enjoy the outdoors responsibly!