DHHS Identifies Season’s First Positive Test for Jamestown Canyon Virus in Mosquito Batch in Keene

Concord, NH – The New Hampshire Department of Health and Human Services (DHHS) has identified the first batch of mosquitoes in 2023 to test positive for Jamestown Canyon Virus (JCV). The batch was collected in Keene on June 6, 2023. 

JVC is an arboviral disease, which means it is transmitted by the bite of an infected mosquito. Reports of JCV in humans have increased in North America over the last several years as awareness of and testing for it have increased. Since the first report of the disease in the State in 2013, New Hampshire has identified 19 cases of JCV. There are no vaccines to prevent JCV and treatment consists of supportive care.

"This finding of the first identification of Jamestown Canyon Virus in New Hampshire serves as a reminder that when enjoying the outdoors, mosquito bite prevention is key in safely enjoying the outdoors,” said Deputy State Epidemiologist Dr. Elizabeth Talbot. “As soon as mosquitoes emerge in the spring, residents and visitors can take steps to protect their health and their family’s health, including using an effective insect repellant, wearing protective clothing, and minimizing outdoor exposure at dawn and dusk, when mosquitoes are most active.”

The arboviral risk level for Keene will be increased to from baseline (no current activity detected) to low. The arboviral risk level indicates the risk that a mosquito will transmit these infections to a person. 

In addition to JCV, the risk for infection in NH by Eastern Equine Encephalitis (EEE) and West Nile Virus (WNV) may increase through the summer and fall until mosquitoes are no longer biting. Residents and visitors of New Hampshire should continue to protect themselves and their family members. Prevention guidelines are included below.

For all mosquito-borne diseases present in New Hampshire, an infected person may not develop any symptoms or only develop very mild symptoms. Early symptoms can include flu-like illness, including fever, muscle aches, headaches, and fatigue. People may progress to more serious central nervous system diseases, including meningitis or encephalitis. Individuals experiencing flu-like symptoms, including fever and headache, are encouraged to contact a healthcare provider.

Anyone with questions about vector-borne illnesses can call the DHHS Division of Public Health Services’ Bureau of Infectious Disease Control at (603) 271-4496 from 8 AM to 4:30 PM, Monday through Friday. For more information, visit the Mosquito-borne Illnesses page and www.cdc.gov. 

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Prevention Guidelines for Mosquito and Tick Diseases

NH Department of Health and Human Services, Division of Public Health Services

1. Eliminate habitat and breeding locations.

• ​​​​​​​Mosquitoes
  • Mosquitoes lay their eggs in standing water. Remove outdoor items that hold water (old tires, cans, plastic containers, ceramic pots).
  • Drill holes in the bottom of outdoor recycling containers, clean roof gutters and ensure proper drainage.
  • If not in use, empty and/or cover swimming pools, wading pools and hot tubs. 
  • Turn over wheelbarrows and change water in birdbaths at least twice weekly.
• Ticks
  • Minimizing areas where hosts for the ticks, such as rodents and deer, can congregate to eat, sleep or feed.

2. Be aware of where mosquitoes and ticks live.

• Weeds, tall grass, and bushes provide an outdoor home for mosquitoes and ticks alike.

3. Protect yourself from bites.

• Make sure that doors and windows have tight-fitting screens. Repair or replace all screens in your home that have tears or holes. 
• Resting mosquitoes can often be flushed from indoor resting sites by using sweeping motions under beds, behind bedside tables etc. and once in flight, exterminated prior to sleeping at night.
• When outside, wear protective clothing such as socks, long-sleeved shirts, and long pants (preferably tucked in socks). Light-colored clothing helps you spot ticks.
• Consider avoiding outdoor activities in the early morning and evening, when mosquitoes are most likely to be biting. 
• Avoid tick-infested areas. If in tick-infested areas, walk in the center of trails to avoid contact with overgrown grass, brush, and leaf litter at trail edges.
• Wear insect repellents, such as one containing 30% or less DEET (N,N-diethyl-methyl-meta-toluamide), Picaridin, para-menthane-diol, IR3535, or 2-undecanone or oil of lemon eucalyptus. Treat clothing with permethrin, which is odorless when dry.
• Vitamin B, ultrasonic devices, incense, and bug zappers have not been shown to be effective in preventing mosquito bites. 
• Shower as soon as possible after spending time outdoors. 
• Check for ticks daily, on you and your pets. Ticks can hide under the armpits, behind the knees, in the hair, and in the groin. 
• Wash and dry clothing after being outdoors. Tumble clothes in a dryer on high heat for 10 minutes to kill ticks on dry clothing. If the clothes are damp, additional time may be needed. 
• Early removal of ticks can reduce the risk of infection. Inspect all body surfaces carefully, and remove attached ticks with tweezers. Monitor your health closely after a tick bite and be alert for symptoms of illness. Contact your physician to discuss testing and treatment.