Thursday, August 15, 2013

Amherst Health Department

Summer 2013

Eastern Equine Encephalitis (EEE)

Frequently Asked Questions

August 13, 2013

1. What is Eastern equine encephalitis?

Eastern equine encephalitis, or EEE, is a virus that causes severe inflammation of the nervous system including the brain.  The disease occurs in humans and other animals, but is only transmitted by getting bitten by a certain type of mosquito; a human cannot get it from another person or animal.

2. Why the increased concern this summer regarding EEE compared to other years?

This summer a sample of mosquitoes collected in Amherst tested positive for the EEE virus.  Also, two horses on the Amherst – Belchertown border tested positive.  Although no humans have tested positive, this indicates an elevated risk to people.  EEE is a rare disease, but last summer there were 7 human cases and 8 animal cases in MA.

3. Who can get the disease and what are the symptoms?

 People of all ages are at risk for infection with the EEE virus, but people over age 50 and younger than age 15 are at greatest risk for developing severe disease.  Most people bitten by an infected mosquito will not develop any symptoms.  Severe cases of EEE infection begin with the sudden onset of headache, high fever, chills, and vomiting.  The illness may then progress into disorientation, seizures, encephalitis (inflammation of the brain) and coma.  Approximately a third of patients who develop EEE die.  It takes 4-10 days after the bite of an infected mosquito to develop symptoms of EEE.  There is no specific treatment for EEE. Antibiotics are not effective against viruses.

4. Can my dog or cat get EEE? How do I protect them?

Yes, dogs and cats can get the illness, but it is very rare.  Horses, llamas, deer and alpacas are susceptible.  So are birds such as ostriches, emus and pheasants and quail. There is a vaccine that is approved only for horses. The timing is important so speak with your veterinarian to schedule. Do not use insect repellents made for humans on your dog or cat.  They have different metabolism and the products can be toxic.

5.  Is there an EEE vaccine for humans? How do I protect myself from getting EEE?

There is no human vaccine for EEE.  The best way to protect yourself is to keep mosquitoes from biting you.  Reduce the chances of mosquito exposure by avoiding peak mosquito times between dusk and dawn and prevent mosquito bites by using repellent and wearing clothing to cover skin.  Please read insect repellent directions thoroughly to assure safe and effective use.

6. Why is the happening in our area?

Massachusetts has 51 types of mosquitoes, but not all carry disease.  Amherst has swamps that have red maple and cedar trees.  This is the habitat of the mosquito that keeps EEE circulating.  A different mosquito transmits West Nile Virus. This mosquito breeds in standing water such as what is found in urban environments such as around the house, in a bird bath, or catch basin where runoff water is found from a street.

7. The town’s risk level was raised. What does this mean?

The Massachusetts Department of Public Health decides when to raise the risk level for a city or town in the Commonwealth. They make this determination due to a number of factors that include looking at mosquito collection data, human clinical cases and veterinary reports.

     A risk level of High means the conditions are likely to lead to infection of a person with EEE are occurring in the area. This means people should adjust outdoor activity to avoid peak mosquito hours from dusk to dawn and avoid nighttime activities near freshwater swamps where EEE activity is most likely.

8. Is the town going to cancel or reschedule activities that are held after dusk?  Sporting events, for example?

Yes. At this time town sporting events will be rescheduled to finish before dusk. This decision is made based on the fact that mosquitoes are attracted to sweat and their habitats are near all of our playing fields.  Likewise, activities such as sitting on grass to watch a movie will be cancelled. This will continue until the first frost. 

5. Is the town suggesting residents stay inside after dusk?

No. We are advising that people consider what type of activity they are participating in and where.  Exercising at dusk in grassy areas has a higher risk for mosquito bites than a walk on pavement wearing long sleeves and pants.  If you choose to engage in activities after dusk, we hope you will take precautions to keep you and other members of your group safe by minimizing exposed skin, using repellents if you choose and being aware of the environment around you.

For more information:

 MA Department of Public Health web page at:

 Town of Amherst web page at:

 Amherst Health Department at 413-259-3077