Eastern Equine Encephalitis Detected in Three States


Health officials in New Jersey, Michigan, and Massachusetts are warning of mosquitos carrying Eastern equine encephalitis (EEE), a potentially deadly virus characterized by chills, fever, malaise, arthralgia, and myalgia.

Health officials in New Jersey, Michigan, and Massachusetts are warning of mosquitoes carrying Eastern equine encephalitis (EEE), a virus that can potentially cause brain swelling leading to death.

The virus has approximately a 30% mortality rate, and many survivors continue to have neurological problems. Spread by infected mosquitoes, the incubation period ranges from 4 to 10 days, and infection can result in either systemic or encephalitic illness. Symptoms for systemic infection include an abrupt onset of chills, fever, malaise, arthralgia, and myalgia. Symptoms for encephalitic patients include fever, headache, irritability, restlessness, drowsiness, anorexia, vomiting, diarrhea, cyanosis, convulsions, and coma.1

Only a few cases are reported each year. The highest number of reported cases in the last decade was in 2012, with 15 reported cases. While there is a vaccine for horses, no human vaccine against EEE currently exists.1

The New Jersey Department of Health confirmed the summer's first case of EEE in August, and urged residents to take precautions against mosquitoes. The statement also urged clinicians to consider patients with compatible symptoms and contact their local health department for testing. Laboratory testing for EEE is currently only available at the State Public Health and Environmental Laboratories.2

As of the statement's release on August 16, EEE was detected in 22 mosquito samples and in 3 horses in the southern and eastern regions of the state.2

The Michigan Department of Health quickly released their own statement regarding residents with the virus. According to their statement, 3 cases of EEE are suspected in residents of Kalamazoo and Berrien counties, in southwest Michigan.3

"These cases, along with confirmed cases in horses and deer in the state, stress the importance of taking precautions against mosquito bites," said Dr. Mary Grace Stobierski, MDHHS state public health veterinarian, in the Michigan Department of Health's statement.3

As of the statement's release on August 26, 6 cases of EEE have been confirmed in horses across three southwestern counties. None of those animals were vaccinated against the virus and all have since died.3

Massachusetts has also seen more EEE activity than normal, with four reported infections4and one death this month as a result of the virus.5The state has issued an informational alert on their website, which said increased activity of mosquitoes at dusk makes those outside at that time more likely to contract the virus.

All of the states issued similar suggestions to avoid mosquito bites and lower risk of contracting the virus. Using insect repellent, wearing protective clothing, and installing screens on doors and windows can also reduce risk of contraction.


  1. Symptoms & Treatment | Eastern Equine Encephalitis | CDC. Centers for Disease Control and Prevention. https://www.cdc.gov/easternequineencephalitis/tech/symptoms.html.
  2. J Fleming. Department of Health Confirms This Summer's First Human Case of Eastern Equine Encephalitis. Department of Health | News | Department of Health Confirms This Summer's First Human Case of Eastern Equine Encephalitis. https://www.nj.gov/health/news/2019/approved/20190816a.shtml. Published August 16, 2019.
  3. MDHHS. MDHHS - Cases of mosquito-borne disease suspected in Michigan residents, Eastern Equine Encephalitis continues to be a threat in Southwest Michigan. https://www.michigan.gov/mdhhs/0,5885,7-339--505643--,00.html. Published August 26, 2019.
  4. EEE in Massachusetts. Mass.gov. https://www.mass.gov/guides/eee-in-massachusetts.
  5. Tufts Medical Center | Wellforce
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