Updated

Updated · WMUR Manchester · Jul 10

Jamestown Canyon Virus Turns Up in 2 New Hampshire Towns, Bringing 2026 Positive Mosquito Sites to 3

Updated

Updated · WMUR Manchester · Jul 10

Jamestown Canyon Virus Turns Up in 2 New Hampshire Towns, Bringing 2026 Positive Mosquito Sites to 3

Q: What subtle flu-like symptoms could signal a rare, mosquito-borne brain infection this summer?

The subtle warning signs are usually mild, flu-like symptoms after a mosquito bite: fever, fatigue, headache, and sometimes cough, sore throat, or a runny nose. With Jamestown Canyon virus, many people have no symptoms at all, but when illness does appear it can start this way within a few days to two weeks after exposure. What makes the virus concerning is that, in rare cases, it can progress to a brain or nervous system infection such as meningitis or encephalitis. Signs that the illness is becoming more serious include a stiff neck, confusion, trouble speaking, loss of coordination, seizures, severe headache, vomiting, or altered consciousness. Those symptoms need prompt medical attention. Health officials in New Hampshire recently detected Jamestown Canyon virus in mosquito batches in Salem and Fremont, after an earlier detection in Exeter. No human or animal cases have been reported there this year, and the overall risk remains low, but the virus is known to circulate in the U.S., especially from late spring through mid-fall. There is no vaccine or specific antiviral treatment, so prevention matters: use EPA-registered insect repellent, wear long sleeves and pants, avoid peak mosquito hours when possible, and remove standing water around homes. Anyone who develops flu-like symptoms after mosquito exposure, especially if neurological symptoms follow, should contact a healthcare provider.

1 articles · Updated · WMUR Manchester · Jul 10

Salem and Fremont mosquito batches collected last week tested positive for Jamestown Canyon virus, New Hampshire health officials said.
The virus can spread to humans; many infections cause no symptoms or mild flu-like illness, but severe cases can lead to meningitis or encephalitis.
No human or animal cases have been identified in New Hampshire so far this year.
Exeter is the only other community where a mosquito batch has tested positive for Jamestown Canyon virus in 2026.