Two Mosquito Pools Found Positive for Jamestown Canyon Virus

Onondaga County Health Commissioner Dr. Indu Gupta announced today that lab results show the presence of the Jamestown Canyon virus in two mosquito pools, one from a trap located on Midler Avenue in Syracuse, and another located in Onondaga Lake Park in Liverpool. This is the first finding of the virus in mosquitoes in Onondaga County since 2014. There have been no known human cases in Onondaga County.

This finding is a result of the Health Department’s mosquito surveillance and control program which collects and tests mosquitoes for viruses. The program also uses larvicides (insecticides) to control mosquito breeding in standing bodies of water. While this virus is rare, the Health Department will report any future findings as part of their weekly mosquito pool testing.

Dr. Gupta explained that, “Jamestown Canyon virus is spread to people by infected mosquitoes. Many people have no symptoms and do not get sick, but some have symptoms such as fever, headache, fatigue, cough and sore throat. Very rarely it can develop into encephalitis. The best way to reduce your risk of infection is by avoiding mosquito bites.”

Personal Protection Measures
The Health Department reminds residents that there are steps everyone should take to protect themselves from mosquito bites during outdoor activities:

  • Wear shoes, light-colored socks, long pants, and a long-sleeved shirt. Tuck in your shirt and tuck pant legs into boots or socks.
  • Consider using insect repellents containing DEET, Picaridin, IR3535, oil of lemon eucalyptus, and other products that have been approved by the Environmental Protection Agency (EPA). Use this EPA search tool to help you choose the repellent product that is right for you, and follow the manufacturer’s instructions on proper use for safety and effectiveness. Insect repellents should be applied only to intact skin or over clothing. Do NOT apply DEET or Picaridin directly onto children’s skin (apply to your own hands and then put it on the child). Repellent should not be used on babies younger than 2 months old.
  • Treat clothing and gear with products containing 0.5% permethrin. Permethrin can be used to treat boots, clothing, and camping gear and remain protective through several washings. Alternatively, you can buy permethrin-treated clothing and gear.

Mosquito-Proof Your Home
It is also important to mosquito-proof your home by replacing or repairing broken screens and getting rid of standing water where mosquitoes breed. Keep your property free of standing water by cleaning clogged rain gutters; turning over wheelbarrows and wading pools when not in use; changing water in birdbaths every four days; properly maintaining swimming pools, outdoor saunas, and hot tubs; draining water from pool covers; and, using landscaping to eliminate low spots where standing water accumulates.

Signs and Symptoms
According to the CDC, there were 4 cases of Jamestown Canyon virus disease reported in New York State from 2010 to 2019. Although many people infected with Jamestown Canyon virus do not have symptoms, the virus can cause severe disease.

  • For people with symptoms, the time from mosquito bite to feeling sick ranges from a few days to 2 weeks.
  • Initial symptoms can include fever, fatigue, and headache. Some people also have respiratory symptoms such as cough, sore throat, or runny nose.
  • Jamestown Canyon virus can cause severe disease, including infection of the brain (encephalitis) or the membranes around the brain and spinal cord (meningitis).
  • Symptoms of encephalitis or meningitis include stiff neck, confusion, loss of coordination, difficulty speaking, or seizures.
  • About half of patients reported with Jamestown Canyon virus disease are hospitalized.
  • Deaths associated with Jamestown Canyon virus infection are rare.

Contact your healthcare provider if you have recently been bitten by a mosquito and are experiencing flu-like symptoms.

More Information and Resources
For more information about Jamestown Canyon virus and mosquito-borne illnesses, contact the Onondaga County Health Department, Division of Environmental Health at 315.435.1649 or visit: