State health officials have confirmed the fifth case of the Jamestown Canyon virus in New Hampshire this year.

State health officials said an adult in Newport has tested positive for the Jamestown Canyon virus, the fifth case of the mosquito-borne disease reported in New Hampshire this year.

The person was hospitalized with left side weakness, unresponsiveness and multiple seizures and remains hospitalized, health officials said.

Jamestown Canyon virus (JCV) is transmitted through the bite of an infected mosquito. According to state health officials, this is New Hampshire’s 14th case of the virus since it was first reported in the Granite State in 2013.

There are no vaccines to prevent JCV and treatment consists of supportive care.

“Although Jamestown Canyon virus is still a rare disease, we are seeing more infections in NH, which is concerning,” said Dr. Benjamin Chan, NH State Epidemiologist. “Similar to other diseases in New Hampshire that are spread through mosquito bites, like West Nile virus and eastern equine encephalitis, infection with JCV can cause a severe neurologic disease. The risk for mosquito-transmitted infections is present from when snow melts in the spring until there is a mosquito killing frost in the fall.”

The “arbo-viral risk level” for Newport — defined as the risk of transmission of infections to people from mosquitoes — is now considered high.

The risk level for surrounding towns of Cornish, Croydon, Sunapee, Goshen, Unity and Claremont will increase to moderate, health officials said.

Risk levels will be adjusted to reflect the end of season risk for 2020, and for awareness of continued risk in the 2021 mosquito season, health officials said.

Early symptoms of JCV include fever, muscle aches, headaches and fatigue.

People infected with JCV or other mosquito-borne illnesses like West Nile virus and eastern equine encephalitis can develop a more serious central nervous system disease like meningitis or encephalitis, health officials said.

Many illnesses caused by JCV are mild, but moderate-to-severe central nervous system involvement requiring hospitalization have been reported, including fatal infections. In New Hampshire, human cases of JCV have been recorded as early as mid-May and as late as early November.

Anyone with questions about vector-borne illnesses can call the DPHS Bureau of Infectious Disease Control at (603) 271-4496 from 8 a.m. to 4:30 p.m. Monday through Friday. More information can also be found online at and


Friday, November 27, 2020