EEE: What You Should Know

The number of mosquitoes infested with Eastern equine encephalitis (EEE) in Massachusetts is the highest it has been in three decades, a "top health official" told The Boston Globe.

The summer's second round of aerial spraying is scheduled to take place in the coming days.

What is EEE?

EEE is a disease caused by a virus.

According to the Massachusetts Department of Public Health (MDPH), EEE is very rare:

Since the virus was first identified in Massachusetts in 1938, fewer than 100 cases have occurred. Over 60 percent of those cases have been from Plymouth and Norfolk counties.

Public health officials are responsible for collecting and testing mosquitoes for disease, including EEE, throughout the summer season. When the disease is found, "public health officials issue warnings to the public."

Most of the time, regional mosquito control workers will drain standing water or kill larvae developing in mosquito habitats to help combat the spread.

If the risk becomes "too great," state agencies consider whether or not to spray towns with insecticides by airplane.

How does it spread?

The virus infects birds that live in freshwater swamps and is spread from bird to bird by infected mosquitoes. If a mosquito infected with the virus bites a horse or human, the animal or person can become sick.

Although humans and several other types of mammals, particularly horses and llamas, can become infected, they do not spread disease.

A list of common disease-carrying mosquitoes in Massachusetts can be found here.

How serious is EEE?

Mass DPH:

EEE can cause severe illness in any age group; however people under the age of 15 are at particular risk. The death rate for humans who get EEE is high, and survivors often suffer severe neurological damage.

Why is it such a risk now?

The risk of getting EEE is typically highest annually from late July through early September.

However, more mosquitoes survived this past winter due to the unseasonably warm temperatures in New England. More mosquitoes around during the summer means more potential carriers of EEE.

What symptoms should you look out for?

The first symptoms of EEE that occur are flu-like: they include a fever (often 103 degrees to 106 degrees Fahrenheit), stiff neck, headache and a lack of energy — all of which occur three to 10 days after a bite from an infected mosquito.

Inflammation and swelling of the brain, called encephalitis, is the most dangerous complication. Some patients who have contracted EEE fell into a coma within a week.

What should you do to prevent it?

MDPH and the Massachusetts Department of Health and Human Services have listed a handful of suggestions to prevent yourself from contracting EEE:

    • Avoid outside areas with notoriously high mosquito activity.
    • Schedule outdoor events and stay indoors between dusk and dawn, when mosquitoes are most active.
    • When you are outdoors, wear long pants, a long-sleeved shirt and socks.
    • Use mosquito repellent — some can cause allergic reactions or are dangerous for children.
    • Install and repair screens to keep mosquitoes out of your home.
    • Remove areas of standing water around your home, twice weekly.

To eliminate standing water:
    • Look around outside your house for containers and other things that might collect water and turn them over, regularly empty them, or dispose of them.
    • Drill holes in the bottom of recycling containers that are left outdoors so that water can drain out.
    • Clean clogged roof gutters; remove leaves and debris that may prevent drainage of rainwater.
    • Turn over plastic wading pools and wheelbarrows when not in use.
    • Change the water in birdbaths every few days; aerate ornamental ponds or stock them with fish.
    • Keep swimming pools clean and properly chlorinated; remove standing water from pool covers.
    • Use landscaping to eliminate standing water that collects on your property.


  • Use mosquito nets on baby carriages and playpens.

  • Report any stagnant water on private property to the board of health.

  • Avoid overnight camping near freshwater swamps.

  • Arrange neighborhood cleanups to destroy mosquito breeding sites.


Helpful Links:

Contact information for Local Mosquito Control Districts:

  • Berkshire County Mosquito Control Project -
  • Bristol County Mosquito Control Project -
  • Central Massachusetts Mosquito Control Project -
  • Cape Cod Mosquito Control Project -
  • East Middlesex County Mosquito Control Project -
  • Norfolk County Mosquito Control Project -
  • Northeast Mosquito Control Project -
  • Plymouth County Mosquito Control Project -
  • Suffolk County Mosquito Control Project -

This program aired on August 8, 2012. The audio for this program is not available.


More from WBUR

Listen Live