New Hampshire resident dies after testing positive for mosquito-borne encephalitis virus

A New Hampshire resident who tested positive for the mosquito-borne infection eastern equine encephalitis virus has died, health authorities in the state said.

The Hampstead resident’s infection was the first in the state in a decade, the New Hampshire Department of Health and Human Services said Tuesday. The resident, whom the department only identified as an adult, had been hospitalized due to severe central nervous system symptoms, the department said.

About a third of people who develop encephalitis from the virus die from the infections, and survivors can suffer lifelong mental and physical disabilities. There is no vaccine or antiviral treatment available. There are typically about 11 human cases of eastern equine encephalitis in the U.S. per year, according to the U.S. Centers for Disease Control and Prevention.

There were three cases of the virus in humans in New Hampshire in 2014, and two of those resulted in fatalities. The health department said the virus, which is rare but serious, has also been detected in one horse and several mosquito batches in New Hampshire this summer.

The virus has also appeared in neighboring states this summer, with cases in humans in Massachusetts and Vermont, the New Hampshire health department said. The virus can cause flu-like symptoms and can also lead to severe neurological disease along with inflammation of the brain and membranes around the spinal cord.

“We believe there is an elevated risk for EEEV infections this year in New England given the positive mosquito samples identified. The risk will continue into the fall until there is a hard frost that kills the mosquitos. Everybody should take steps to prevent mosquito bites when they are outdoors,” said state epidemiologist Dr. Benjamin Chan.