A pool of mosquitoes caught in a trap in the town of Sullivan has tested positive for Jamestown Canyon virus (JCV), according to Madison County Public Health.
While there have been no human cases reported in Madison County, local officials are urging residents to take precautions.
JCV can spread to people from the bite of an infected mosquito. But the virus does not spread from person to person.
Many people infected with JCV do not develop symptoms, but some do get sick and, in rare cases, infection can lead to encephalitis (inflammation of the brain) or meningitis (inflammation of the spinal cord).
Between 2011 and 2024, there were 336 reported human cases in the United States with 12 deaths, according to the Centers for Disease Control and Prevention. There were five human cases in New York during that time period, including one in Madison County in 2013.
JCV has turned up in mosquito pools in Madison County before: in one pool in 2024, 2023, 2014 and 2015; in two pools in 2022; and in 14 pools in 2017, according to county health department records.
There have been no human cases in Oneida or Herkimer counties. The virus did turn up in “non-human activity” in Oneida County last year, which could mean a mosquito pool or an animal case, according to the CDC.
Other mosquito-borne illnesses
Oneida and Madison counties, like a number of other counties in the state, conduct mosquito surveillance every summer, sending traps placed in likely areas to the New York State Department of Health Wadsworth Laboratory for analysis.
The primary targets of this surveillance are West Nile Virus and the Eastern Equine Encephalitis virus, both of which are more common in New York than the Jamestown Canyon Virus.
Last year a horse tested positive for West Nile Virus in Herkimer County. And horses in both Oneida and Madison counties tested positive for EEE.
Across the U.S., 60,992 human cases of West Nile were reported with 3,134 between 1999 and 2024, according to the CDC. Those numbers include 1,291 cases in New York, one of which was in Herkimer County, according to the CDC.
There were 215 human cases of EEE across the country between 2003 and 2024, including 84 deaths, according to the CDC. Of those cases, 10 were in New York, but none in Oneida, Madison or Herkimer counties.
Last year New Yorkers were also diagnosed with chikungunya, dengue fever and malaria, all mosquito-borne illnesses, but all those cases were associated with travel.
Flanders virus, Potosi virus, cache virus and Highland J virus have also been detected in mosquito pools in Madison County in recent years.
Jamestown Canyon symptoms
When people do get symptoms of Jamestown Canyon virus, symptom usually occur within a few days to two weeks. Symptoms may start with a fever, fatigue, and headache.
Respiratory symptoms may develop, including a sore throat, runny nose and cough. And meningitis and encephalitis can, rarely, occur.
Symptoms of encephalitis or meningitis include a stiff neck, confusion, loss of coordination, difficulty speaking or seizures. Some people who develop severe disease may need to be hospitalized; most recover from the virus.
Prevention
The best way to prevent Jamestown Canyon virus or any other illness carried by mosquitoes is to avoid getting bitten.
To protect from mosquito bites, Madison County Public Health advises residents to do the following:
Madison County Public Health also advises doing the following to reduce the areas for mosquitoes to breed:
Mosquitoes need as little as a bottle cap of water to lay their eggs and do not travel very far from where they are born.
This article originally appeared on Observer-Dispatch: Jamestown Canyon virus detected in Madison County mosquito pool
Reporting by Casey Pritchard and Amy Neff Roth, Utica Observer Dispatch / Observer-Dispatch
USA TODAY Network via Reuters Connect
