Eastern equine encephalitis (EEE) is spread by the bite of an infected mosquito. EEE is a rare but severe viral disease spread by infected mosquitoes that can infect people and horses. People of all ages can become infected, but people over the age of 50 and younger than the age of 15 are at a high risk of getting sick.

While most people bitten by an infected mosquito will not develop symptoms, severe cases may begin with the sudden onset of headache, high fever, chills and vomiting. The illness may then progress into disorientation, seizures, encephalitis and coma. Approximately a third of patients who develop EEE die, while many patients who survive EEE experience neurologic impairment. 

There is no commercially available human vaccine for EEE, and the best protection is to prevent mosquito bites.

See "How can I reduce my risk of infection from EEE?" below for more information.

EEEV cycles between the Culiseta melanura mosquitoes and birds. People and horses often become infected by different mosquitoes (known as bridge vectors) that feed on both birds and animals.

EEE is only spread to people and horses through the bite of an infected mosquito. EEE is not spread person-to-person, people to animals, or animals to people. People and horses are considered "dead-end" hosts. This means they do not spread the virus, even though they get sick, to mosquitoes that bite them.

(Image from the Centers for Disease Control and Prevention)

CLICK HERE to learn more about how EEE spreads.

Some people who are infected with EEEV will not develop any symptoms. Symptoms of EEEV infection typically appear 4-10 days after being bitten by an infected mosquito.

The type of symptoms can depend on the age of the person. People over the age of 50 and younger than the age of 15 are at greatest risk for developing severe disease. Severe cases of EEE infection begin with the sudden onset of headache, high fever, chills, and vomiting that may progress into disorientation, seizures, encephalitis (inflammation of the brain), and coma. Approximately a third of patients who develop EEE die, and many of those who survive have mild to severe brain damage.

CLICK HERE To learn more about EEE symptoms.

Health care providers diagnose EEE based on your signs and symptoms, history of living in or traveling to an area where EEEV is known to circulate, history of possible exposure to the mosquitoes that can carry eastern equine encephalitis virus, and laboratory testing of blood or spinal fluid

There are no specific medications to treat EEE. Rest, fluids, and over-the-counter pain medicines may relieve some symptoms. For severe disease, patients often need to be hospitalized to receive supportive treatment, such as intravenous fluids, pain medicine, and nursing care.

(Image from the Centers for Disease Control and Prevention)

The following precautions are recommended to reduce the risk of infection from EEE and other mosquito-borne illnesses:

• Consider wearing long sleeves and tucking pants into socks and shirts into pants when outdoors at dusk or dawn, the time of day when mosquitoes are most active.
• Use insect repellents containing DEET. You can find more information on repellents on the EPA website. Be sure to follow the insect repellent label directions. Children should not handle repellents directly. Instead, adults should apply repellents to their hands first and then gently spread them on the child's exposed skin. Avoid applying directly to children's hands. After returning indoors, wash your child's treated skin and clothing with soap and water or bathe the child.
• Make sure there are screens in the windows and doors of the home. Make sure the screens are free of rips, tears and holes.
• Eliminate all standing water in yards and around the home and property where mosquitoes can breed, including plastic containers, pool covers, wading pools, ceramic pots, clogged drainpipes and wheelbarrows. Also, change water in bird baths twice a week.

CLICK HERE To learn more about mosquito bite prevention.

• Governor Hochul Announces Statewide Action Following Confirmed Case of Eastern Equine Encephalitis | Governor Kathy Hochul (ny.gov)
• 2024-09_eee_declaration.pdf (ny.gov)
• Human Case of Eastern Equine Encephalitis Confirmed In Ulster County (ny.gov)
• Eastern Equine Encephalitis Confirmed In Horses In Multiple New York State Counties (ny.gov)
• Eastern Equine Encephalitis (EEE) (ny.gov)
• About Eastern Equine Encephalitis | Eastern Equine Encephalitis Virus | CDC
• Repellents: Protection against Mosquitoes, Ticks and Other Arthropods (EPA)