CONCORD, N.H. — The New Hampshire Department of Health and Human Services announced that an adult from Kingston tested positive for both Jamestown Canyon virus (JCV) and Powassan virus (POW).

This is the first time these vector-borne diseases have been identified in the state in 2019.

JCV is transmitted by infected mosquitoes and POW is transmitted by infected ticks. There are no vaccines to prevent JCV or POW and treatment consists of supportive care.

The Kingston resident had no recent history of travel outside our state and spent a great amount of time outdoors.

State officials warn people to be careful and take precautions when enjoying the outdoors this summer.

"From spring until fall, New Hampshire residents and visitors are at risk for a number of different infections from the bite of mosquitoes and ticks, and this case highlights the risk from both," said Dr. Benjamin Chan, state epidemiologist. “In addition to Jamestown Canyon virus and Powassan virus, there are a number of other viral and bacterial infections that can be transmitted by mosquitoes and ticks in New Hampshire, and we recommend that residents and visitors continue to take basic steps to prevent mosquito and tick bites in order to stay healthy.”

Jamestown Canyon virus is a mosquito-borne pathogen that circulates widely in North America primarily between deer and a variety of mosquito species, but it can also infect humans, according to the DHHS. First reported in the early 1970s, reports in humans are rare but have been increasing over the last several years.

This is New Hampshire’s seventh case of JCV since the first report of the disease in 2013. Most reported illnesses caused by JCV have been mild, but moderate-to-severe central nervous system involvement has been reported, according to the DHHS.

The Powassan virus infection is similar to mosquito-borne viruses like JCV, West Nile virus and Eastern equine encephalitis, but is transmitted to people by infected ticks, according to the DHHS. POW was identified as a cause of human illness in the late 1950s. In the last decade, 144 cases of POW have been detected in the United States, according to the DHHS.

This is New Hampshire’s fourth case of POW, also since 2013. In New Hampshire, the black-legged tick is the most likely to transmit this virus to people. Some people who are infected may experience mild illness or no symptoms while others can suffer brain inflammation that could be disabling or even fatal, according to the DHHS. 

Residents and visitors to New Hampshire should protect themselves and their family members by using effective mosquito and tick repellant containing DEET, Picaridin or oil of lemon eucalyptus; wearing protective clothing; removing standing water from around the house; being mindful of tick habitat by keeping grass cut short, and performing frequent and daily tick checks with immediate tick removal.

Anyone with questions can call the DHHS Division of Public Health Services Bureau of Infectious Disease Control at 603-271-4496 or visit and

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