What You Need to Know About EEE on the South Shore


Dr. Todd Ellerin

Todd Ellerin, MD, Director of Infectious Disease

The calendar may say “September,” but there are still several weeks left to get out and take advantage of the summer weather. However, enjoying the great outdoors during the summer means potential encounters with insects, some of which may carry disease.

In a previous blog post, I discussed certain tick- and mosquito-borne illnesses, particularly Lyme disease and West Nile virus. However, there’s another mosquito-borne illness that seems to end up in the headlines every summer: EEE.

Eastern Equine Encephalitis, more commonly known as EEE, is an inflammation of the brain that is caused by a virus transmitted from mosquitoes to humans. Cases of EEE are rare, but dangerous: EEE is fatal in a third of the patients who develop it, according to the CDC.

Why is EEE in the news?

With summer winding down, you wouldn’t expect to see a mosquito-borne illness back in the headlines. However, a few weeks ago the Massachusetts Department of Public Health announced the first confirmed case of EEE in Massachusetts since 2013, as a man in Plymouth County was diagnosed with the condition. 

That announcement came just a few days after the DPH announced it would conduct localized aerial spraying to mitigate the risk of EEE to the public. The aerial spraying covered or partially covered a number of towns on the South Shore and in surrounding communities that are considered to be at "High" or "Moderate" risk from the virus.

Overall, there have been a total of 7 confirmed human cases of EEE in Massachusetts. 

Meanwhile, the Patriot Ledger reported in late August that two mosquitoes tested positive for the virus in Weymouth, home of South Shore Hospital.

"High" risk towns include Bridgewater, East Bridgewater, Halifax, and Whitman. "Moderate" risk towns include Abington, Braintree, Duxbury, Hanover, Hingham, Kingston, Marshfield, Norwell, and Weymouth. You can find a full list of impacted areas on the DPH website.

The aerial sprayers use an insecticide to target mosquito populations that can’t be easily reached by ground spraying. Don’t worry — the insecticide isn’t harmful to humans.

Going forward, the DPH may perform additional sprayings if necessary, as the risk level is still considered "Critical," “High,” or "Moderate" in dozens of Massachusetts communities. While cases of EEE are rare, it’s always a good idea to play it safe.

What are the symptoms of EEE?

Common symptoms of EEE include fever, headache, nausea, and vomiting. Rapid development of confusion (which can be associated with fever) often occurs as well.

If you are experiencing these symptoms, contact your primary care provider as soon as possible. The prognosis for EEE is extremely guarded.

Fortunately, even with countless mosquito bites every summer, EEE remains extremely rare.

How can you protect yourself from EEE?

While terms like “aerial spraying” and “critical risk levels” may seem intimidating, you can protect yourself from EEE by taking the normal precautions against mosquitoes.

These precautions include:

  • Eliminating breeding grounds Mosquitoes use standing water to breed. Take steps to eliminate sources of standing water (like kiddie pools, birdbaths, and buckets) in your backyard.
  • Applying bug repellent Using bug repellent is always a good idea when going outdoors in the summer, especially if you’ll be outside at dawn or dusk. Be sure to read the label on your bug repellent for information on how often you’ll need to reapply.
  • Mosquito-proofing your home You don’t want to have a mosquito buzzing around your house — especially while you’re sleeping! Check your screens and doors for any tears or openings that could allow mosquitoes inside.


Dr. Todd Ellerin is the Director of Infectious Disease at South Shore Health.