The Maine Center for Disease Control and Prevention confirmed the state’s first human case of neuroinvasive Eastern equine encephalitis Friday. The rare, mosquito-transmitted disease kills about one-third of the people who contract it, and can leave survivors with brain damage caused by swelling. It previously had been confirmed in other states, including two people this year in neighboring New Hampshire, but until Friday no humans had been reported to have contracted EEE in Maine since the state began testing in 1964.

“It’s not a surprise,” said Dr. Sheila Pinette, director of the Maine Center for Disease Control. “Eastern equine encephalitis has been in the state for a number of years. It was just a matter of time before the cases were going to occur.”

Severe cases that involve inflammation of the brain are reported in five to 10 people nationwide annually, according to the federal Centers for Disease Control and Prevention. Symptoms, which appear four to 10 days after a person is bitten by an infected mosquito, can include the sudden onset of headache, high fever, chills and vomiting. Disorientation, seizures and coma can follow.

Maine’s confirmed case was found in a York County adult over 60 who began feeling sick in late July and had to be hospitalized in August, first in Maine and then in Massachusetts as the disease worsened. The person, whom Pinette would not identify, is back in York County recuperating at home under family members’ care, she said.

“My understanding is the neurological deficiencies are mild,” Pinette said.

Initial tests for EEE were inconclusive when the York County patient was hospitalized on a respirator and under close watch. It can often take weeks for a person’s body to create antibodies for EEE that can be detected in the bloodstream. Medical workers took another blood sample after the person had recovered, and that sample tested positive for EEE antibodies, first in a commercial laboratory on Oct. 1 and then again at Maine’s Health and Environmental Testing Laboratory in Augusta on Thursday, Pinette said.


Since antibiotics are not effective against viruses, and no effective anti-viral drugs to combat EEE have been discovered, treatment for the disease usually relies on giving patients respiratory support and IV fluids while preventing other infections.

The Maine CDC announced in early September that the EEE virus had been detected in 22 mosquito pools in York County and in an emu in Cumberland County. The disease also had been detected in mammals and mosquitoes this year in New Hampshire and Massachusetts.

In previous years, the threat of EEE in other states had caused officials in some towns to restrict outdoor activities after dusk.


The disease is spread when birds bitten by infected mosquitoes fly to another area and are bitten by other mosquitoes, who then spread the disease to other mammals, including humans. The disease is not transmitted person to person, and larger mammals are generally considered dead-end hosts because the concentration of the virus in their bloodstreams is usually insufficient to infect mosquitoes.

There is no vaccine or preventive drug for EEE and the best way to keep from getting it is to reduce exposure to mosquitoes by using repellent and wearing protective clothing when outdoors. A key tactic in fighting the disease is to eliminate the standing water around houses and yards where mosquitoes lay their eggs.


While the virus has only been detected in southern Maine, it is likely much more widespread in the state than that, according to Jim Dill, a pest management specialist with the University of Maine Cooperative Extension in Orono.

Dill said the state has only two biosecure laboratories that can regularly test mosquitoes and birds: the state lab in Augusta and a lab at Maine Medical Center in Portland.

Mosquito trapping and testing isn’t being done in northern Maine, but testing on white-tailed deer confirms that the disease has spread.

“They pretty much found EEE in the deer everywhere in the state,” Dill said.

A Democratic state representative from Old Town, Dill spoke in favor of a bond issue on the statewide ballot in the Nov. 4 election that would fund the creation of a biosecure laboratory to be run by the University of Maine Orono’s Cooperative Extension Service.

Question 2 asks voters: “Do you favor an $8 million bond to support Maine agriculture, facilitate economic growth in natural resource based industries, and monitor human health threats related to ticks, mosquitoes, and bedbugs through the creation of an Animal and Plant Disease and Insect Control laboratory administered by the University of Maine Cooperative Extension?”


Dill said having that lab would allow the state to step up its mosquito testing in addition to the other services the lab would offer.

“If you think of people in Maine, we grew up with mosquitoes. It used to be, it’s just a mosquito, squash it,” Dill said. “It’s not like that anymore.”


EEE infection can cause two types of illness: systemic and encephalitic. The majority of cases are systemic infections, a milder disease that lasts about a week or two with fevers and chills but no nervous system involvement. Systemic infections often pass without hospitalization and usually go unreported, according to the U.S. CDC.

About 4 percent to 6 percent of those infected develop encephalitic EEE, which involves swelling of the brain and kills about one-third of those who contract it.

Another third suffer permanent brain damage and the remainder survive without serious complications, Pinette said.

“The spectrum is extremely broad and varies individually because each person is different,” she said.

The threat of infection drops greatly as the temperature drops with the approach of winter. Mosquitoes become inactive at about 45 degrees and below, Pinette said.

Maine officials will continue mosquito trapping until Wednesday, she said.

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