The Standard-Times asked readers what their questions are about the EEE virus, its threat to animals and humans, and the best ways people can protect themselves from it.

In response, we received more than 50 questions, and, after eliminating duplicates, sent them to the state Department of Public Health to be answered. The answers below are grouped  by general topic. All answers are by Dr. Catherine Brown, state epidemiologist with the Bureau of Infectious Disease and Laboratory Sciences at DPH, unless otherwise noted.


Symptoms of EEE

Do the bites look just like any other mosquito bite?

You cannot tell by the bite if the mosquito was carrying EEE or even if it was a species of mosquito that can carry EEE.

What are the symptoms of EEE? What are the signs if you have it?

We don’t know if everyone that gets bitten by an infected mosquito gets EEE. But for those that do, the first symptoms begin 3-10 days after the mosquito bite and start with a high fever, headache and chills. As the virus gets into the brain, the person gets worse and may experience disorientation, seizures, coma and death in about 40 percent of cases.

What is the length of risk period?

The first symptoms begin 3-10 days after the mosquito bite.


Treatment for EEE

Is there any cure or treatment?

EEE is caused by a virus and there are no specific medications to treat this particular virus. Hospitalized patients are given supportive care to help encourage their body’s immune system to help fight off the virus.

Do I have to notify someone if I do get bit by a mosquito, knowing the chances of it could or couldn’t be EEE?

The most important thing to do to prevent EEE is to take steps to avoid mosquito bites. Once you have been bitten, there isn’t any way to tell if it was a mosquito that was carrying EEE or if you will get the disease.

Is it something that can be cured if caught early?

There is no specific treatment for EEE.

Can you be treated and actually live?

EEE is a serious disease and about 40 percent (4 in 10) of patients with the disease will die from it. Many survivors are left with a permanent neurologic impairment. However there are some individuals that recover completely.

Why isn’t there a cure?

We have antibiotics for diseases caused by bacteria but developing antivirals to treat disease caused by viruses is more difficult. Only certain viruses, like influenza or HIV, have medications that can be used to treat them.

If you had it before and you take meds for it, can you catch it again?

People that survive EEE infection are probably immune for the rest of their life.


State response to EEE

Why isn’t Mattapoisett a critical area?

Based on the criteria laid out in the Massachusetts Arbovirus Surveillance and Response Plan, risk levels are assessed using a combination of mosquito testing data, evidence of human or animal cases, historic evidence of risk and presence/absence of appropriate habitat.

Why wasn’t spraying started earlier in the season?

Aerial spraying is only one tool used to combat risk from mosquito-borne disease. The foundation of all risk reduction remains personal protection (mosquito repellent, long sleeves and pants, avoiding outdoor activities between dusk and dawn, repairing window and door screens, and dumping standing water). Most communities in the highest risk areas also belong to local mosquito control projects who perform truck-based ground control of mosquito populations. This type of response occurs early in the season and is often successful in adequately reducing risk. Aerial spraying is used when the cumulative use of all other tools is insufficient to reduce risk and is most effective when used over large areas of high risk, especially including places where there are not enough roads to adequately cover the area.

Is spraying continuing until the threat is gone and how frequently?

The risk from mosquito-borne disease will continue until the first hard frost. However, mosquito spraying efficacy substantially decreases once nighttime temperatures fall below 60 degrees and cannot occur once temperatures fall below 50 degrees. In most years, spraying stops sometime during the first half of September due to weather conditions.

Why isn't there coverage of other states? Do they also have an outbreak?

EEE is a disease that does not occur nationally and is generally restricted to states along the East Coast and a few in the upper Midwest. Of these states Massachusetts has more EEE activity over time than any state other than Florida. However, this year is producing EEE activity in other states and there have been animal and/or human cases in Florida, Delaware, New Jersey, New York, Connecticut, Rhode Island, New Hampshire, Maine, Michigan and Wisconsin.

Why are so few cases resulting in such panic and such a dramatic response by our state with the poisoning and killing of more bees?

Although EEE is a rare disease, it is serious. About 40 percent (4 in 10) patients with the disease will die from it and many survivors are left with a permanent neurologic impairment. Even children can get this disease and the results can be devastating. Unusual mosquito control measures, such as aerial spraying, are applied specifically in areas of increased risk and only when there is evidence that risk is not being sufficiently reduced using a combination of personal protective measures (mosquito repellent, etc.) and ground-based mosquito control measures. The pesticide product that is used is applied in a such a way as to minimize impacts on bees and other insects. Surveillance done following previous aerial sprays has not identified any substantial die-offs of other insect species.


Science behind EEE

The samples that they test, they always say how many were tested positive, but never say out of how many were tested - tested positive.

This is a very interesting question. Mosquito traps can catch tens of thousands of mosquitoes in one night and only a small portion of them are tested. The mosquitoes are sorted by species and then a proportion of the species of concern are tested for virus. Up to 50 mosquitoes are put into one test tube, ground up, and then tested by looking for the genetic material of the virus. As of Monday, Sept. 9, 2019, MDPH had tested 6,846 mosquito samples with each sample containing up to 50 mosquitoes. 400 of those samples had tested positive, meaning at least one mosquito in each sample was carrying the virus.

What is the estimated percentage of mosquito population on SouthCoast carrying the disease...1%? 50%? 90%?

Because there are millions of mosquitoes in the environment and we only test a very small proportion of them (see question above), it is not possible to estimate the proportion of all mosquitoes carrying the EEE virus in an area.

Can dogs get EEE?

There is only one published report of a couple of puppies getting EEE in the southeastern United States. However, our domestic dogs and cats do not seem to be particularly susceptible to the virus. The puppies in question were very young and were housed exclusively outdoors. They probably got sick because they had repeated mosquito exposure and under-developed immune systems due to their age. However, horses, llamas and alpacas are very sensitive to EEE. We have also had some cases in sheep, goats and cows.

What is the impact of spraying on other species, like bats who help contain mosquito populations?

Bats don’t consume as many mosquitoes as you may think. But the question about impact on other species is a good one. There are no wild animal species in Massachusetts that rely solely on mosquitoes for food. Mosquitoes are too small to be very good food sources – too much work for not enough calories. The pesticide product used to kill mosquitoes is a broad spectrum product and can affect other insect species. The product is applied in very small quantities, 1 tablespoon per football field, and is sprayed as a very fine mist. The tiny droplets have to come into contact with the mosquitoes to kill them. The droplets are so small that they are less likely to affect larger insects. In addition, mosquitoes are most active at night which minimizes the number of other species that could be exposed.

Where are all of the EEE mosquito pools?

We have been trying to stop using the term “mosquito pools” because it is misleading. It makes people think that there are pools of water with mosquitoes in them and that is what is being tested. Adult, flying mosquitoes are trapped and tested, only young mosquitoes, known as larva, are found in water. The term pool comes from the fact that we test mosquitoes in groups of 50, this is known as a “pooled sample”.


Prevention and other questions

When will the threat end?

Although risk starts to decrease in mid- to late-September as the mosquito populations begin to decline, some risk will persist until an area has had a hard frost.

Is it safe to kayak, is boating safe?

In areas of the Commonwealth that are at high or critical risk, the recommendation is to avoid outdoor activity between the hours of dusk and dawn. During the day, people who are active outdoors should use mosquito repellent and use long sleeves and pants weather permitting.

How often and when should you apply bug spray?

First, it is very important to select a repellent which has an EPA-registered active ingredient. Consumers should look closely at the label for an EPA symbol. Manufacturers of products with that type of active ingredient have provided data for review by the EPA to prove that their product is both safe and effective. Second, any product that you choose should always be used according to the directions on the label.