Home / Health / JCV Detected in NH Mosquitoes: Health Alert
JCV Detected in NH Mosquitoes: Health Alert
3 Aug
Summary
- Jamestown Canyon Virus found in mosquito batches in six NH towns.
- No human JCV cases identified in New Hampshire this year.
- Less than 30 towns in NH sponsor mosquito trapping programs.
Jamestown Canyon Virus (JCV) has been identified in mosquito samples from six communities in New Hampshire, with recent detections in Derry and Hampton. This follows earlier positive tests in Salem, Exeter, and Kingston. As of August 3, 2026, no human cases of JCV have been reported in New Hampshire this year.
JCV is transmitted to humans through the bites of infected mosquitoes. Symptoms can range from fever and headache to more severe neurological conditions like encephalitis. Currently, there are no vaccines or treatments available for the virus. While found nationwide, most human cases occur in the upper Midwest from late spring through fall.
In 2026, New Hampshire has tested 20 individuals for mosquito-borne infections, none of whom have tested positive for JCV or West Nile Virus. Last year, one human case was recorded, and in 2024, three cases were reported, though one was likely contracted out of state. Less than 30 towns, primarily in the Seacoast area, sponsor mosquito trapping programs, with others including Manchester, Nashua, Derry, and Londonderry also participating.
