Maine CDC confirms first human EEE case, voices concern

A joint report with Shelby Hartin
Originally published Nov. 7, 2014

ORONO, Maine — On October 10, the Maine Center for Disease Control and Prevention confirmed the state’s first human case of Eastern equine encephalitis, one of the most severe and deadly mosquito-transmitted diseases in the United States.

The patient, identified as a mature adult of York County, tested positive for the virus on Oct. 9, and is recovering at home, according to a public health alert issued by Dr. Sheila Pinette, director of the Maine CDC.

The patient’s name was not made available.

The rare illness often has no effect on those who contract it, but in severe cases sudden onset of headache, high fever, chills and vomiting can take place, which may progress into disorientation, seizures or coma. With a mortality rate of one-third and significant brain damage being the result in survivors of severe cases, EEE remains a grave threat to public health.

While the virus has been found in mosquitoes, birds and some mammals in Maine, this marks the first time a human case has been confirmed in the state. Maine was among the last New England states to avoid a human case, but now the epidemiology of the disease is coming into question as it appears to be moving northward.

Click here for an interactive map plotting confirmed cases of EEE in New England since 2010.


EEE is spread to humans and other mammals via infected bridge mosquitoes that feed off multiple forms of hosts, such as birds and mammals. Birds often act as primary hosts for the virus once bitten by an infected mosquito. As other mosquitoes feed off infected birds, they too can carry the virus to mammals, including humans, according to the CDC.

Graphic by Shelby Hartin. Images via Wikimedia Commons.
Graphic by Shelby Hartin. Images via Wikimedia Commons.

Only about a third of transmitted viruses manifest into the infection, and of those a third will die. Another third will have lasting neurological effects, and the rest will recover. Some who develop EEE won’t even show symptoms.

The disease has two forms: systemic and encephalitic.

Systemic infection has an abrupt onset and is characterized by flu-like symptoms including chills, fever and a general feeling of being unwell. Systemic infection can last anywhere from one to two weeks if it does not develop into the encephalitic form. The encephalitic form is abrupt in infants, but occurs after several days of systemic infection in older children and adults. Symptoms of encephalitic form include fever, headache, vomiting, diarrhea, convulsions and coma.

Death typically occurs between two to 10 days after onset of symptoms, and those who survive are usually left with mental and physical impairments, from brain dysfunction and intellectual disabilities to personality disorders, seizures and paralysis. Many who develop these impairments die within a few years of development, according to the CDC.

There is no treatment.

Humans are known as dead-end hosts, meaning that they cannot infect any mosquitoes that bite them.

With the first diagnosis of EEE in a Maine resident, the Maine CDC is concerned that numbers will rise in the coming years.

“I think we might identify that the risk is here. It was only a matter of time until we saw a human case,” said Sara Robinson, an epidemiologist with the center’s Infectious Disease Epidemiology Program.

Robinson says the time between early to mid-fall is when the risk of contracting the virus is highest, and that those at the highest risk are usually under the age of 15 or over the age of 50.


CDC concerns over future transmission of the deadly EEE virus bring attention to the state of research efforts being conducted on Maine’s vector-borne diseases.

The University of Maine Cooperative Extension system provides services related to the vector of EEE, the mosquito. The Insect Pests, Ticks and Plant Diseases branch of the extension operates year round and offers diagnostic services to the public, which include plant disease identification, insect and insect injury identification, and nutritional and cultural problem assessment.

Since its inception in 1989, the lab has served over 25,000 citizens of Maine. That number becomes more significant when observing the lab where work is done — a small office barely large enough for one person.

Jim Dill, a pest management specialist at the Cooperative Extension, has done extensive work in this lab with mosquitos that carry EEE. One of his main roles is integrated pest management, which requires him to examine different aspects of management and control of pests and crops in order to reduce the use of pesticides.

James Dill. Alan Bennett, photographer.
James Dill. Alan Bennett, photographer.

Dill’s involvement with EEE began in 2000 after West Nile Virus first made its debut in New York. The abrupt appearance of the virus led to many questions about how the disease erupted and why it hit so quickly.

The Centers for Disease Control and Prevention then reached out to resources in Maine with the capabilities of trapping and testing mosquitoes. One of these resources was UMaine’s cooperative extension. Working with other resources in the state, they were able to trap and test mosquitoes.

Dill explained that the lab tested mosquitoes from southern Maine up through Orono to test for WNV. During the testing process, the lab decided to look for other mosquito-borne diseases and it turned out that EEE was present in the testing pool.

“EEE on occasion had been found in Maine, but just in a few birds. So, in this whole process of testing mosquitoes and testing dead birds, we found that there was EEE here in the state,” Dill said.


But, after nine years of trapping and testing, funding started to run dry and cases were on the rise — 15 horses were killed by the disease in 2009, a flock of 30 farm-raised pheasants in Lebanon died in 2012, and last year the virus led to the deaths of two horses in Maine.

Since 2009, testing has been focused primarily on more densely populated areas, but only south of Portland. The cooperative extension still has the tools to trap mosquitoes, but focus and funds have shifted to tick research.

Dill explained that knowledge of this disease and how it spreads is limited and that more research is needed to grasp the epidemiology of the disease.

“This is a big enough problem that there were two or three bills in front of legislature last year dealing with the problem.”

Some of these bills included LD1808, titled “An Act To Protect the Public from Mosquito-borne Diseases.” This bill establishes that the Department of Health and Human Services is the lead agency in the State for monitoring for mosquito-borne diseases. It also authorizes the Commissioner of Health and Human Services to declare a mosquito-borne disease a public health threat, among other things.

In addition, LDs 1567, 1568 and 1569 addressed mosquito-control activities, like aircraft spraying, in response to mosquito-borne disease public health threats.

The Nov. 4 ballot also addressed the need for further research in these areas with Question 2, which asked if voters would choose to allocate $8 million in bonds to assist Maine agriculture and protect Maine farms through the creation of an animal and plant disease and insect control facility administered by the University of Maine Cooperative Extension Service.

Funds from Question 2 will expand Maine’s efforts to research deadly vector-borne illnesses north of Augusta. Currently, the only two labs that can regularly test mosquitoes and birds are at Maine Medical Center in Portland and the state lab in Augusta, Dill said. This is important for the state because the Maine CDC does not conduct research, according to Sara Robinson, although — while unable to give a dollar amount — she acknowledged that Maine CDC has money going toward surveillance funding to track infected mosquito pools.

EEE has been detected in 22 mosquito testing pools in York County and an emu in Cumberland County that later died from the virus. Seven mosquito pools collected on Sept. 30 also tested positive for EEE, according to the Maine CDC.

These results, however, only cover a portion of the state.

Dill confirmed that EEE has been found in deer throughout Maine, and chances are high that mosquitoes carry the disease across the state as well. Without necessary funding to confirm suspicions, EEE and its effects remain largely unknown in most of Maine.



The question then remains — what should one do to prevent the spread of this deadly illness? The first step is awareness, which is often lacking in those who are most susceptible to contracting EEE, like athletes.

As the only university in the state to host Division I level athletes, UMaine is home to a myriad of them, from soccer players to runners and everything in between. Although much of their time is spent outdoors, many are unaware of the dangers mosquitoes pose to their health.

As a runner on the cross country team at UMaine, Carolyn Stocker’s job is to be outside, braving the elements and the bugs. Her prevention methods? Nonexistent.

“I usually run outside every day of the week. I actually am really bad about protecting myself from mosquitoes and usually don’t use bug spray because of the smell and fumes. I am somewhat aware of the dangers of mosquitoes but not 100 percent sure of the specifics,” she said.

Stocker added that she was used to being bitten, as were her teammates. The same can be said for players on the UMaine soccer team.

“The soccer fields here at UMaine are surrounded by woods, which are highly populated with mosquitoes,” said Alexandra Abrahams, a UMaine student and member of the women’s soccer team.

“All throughout the summer whenever we’re practicing, girls are getting bitten all the time by mosquitos and I’m sure they’d be terrified as well to know that they could die from those mosquitoes biting them,” she added.

Athletes like Stocker and Abrahams, who are at the highest risk of infection from dangerous mosquito-borne illnesses, bring to light the fact that because there is no treatment, prevention is the only option.

Sara Robinson offered some tips for prevention success.
Wearing repellants is the best thing one can do to prevent contracting the virus, she said. Five repellants are approved by the U.S. Environmental Protection Agency for use in repelling mosquitoes, including those that may carry EEE. They are DEET, picaridin, IR3535 and oil of lemon eucalyptus – which are approved for use on skin – and permethrin, which is approved for use on clothing only.

Many brands of insect repellants use these compounds in their formulations, and a complete list can be found using the search tool on the EPA’s website.

Robinson further suggested that hikers and campers check screens or mosquito nets on tents for any signs of wear, damage and holes, and make sure they are in good condition. “That’s going to keep mosquitoes out,” she said.

Hikers and campers can invest in bed netting that will provide further protection, as well as wear long sleeves and pants if the weather provides. The CDC also recommends draining artificial sources of standing water where mosquitoes can thrive, such as flower pots and small, inflatable pools.

“For this time of year, it’s basically preventing getting bitten,” Robinson said. “If they can’t get to your skin they aren’t going to be able to bite you.”

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: