DHHS Identifies Jamestown Canyon Virus And Powassan Virus In New Hampshire

Concord, NH - The New Hampshire Department of Health and Human Services (DHHS) announced that an adult from Kingston, NH tested positive for both Jamestown Canyon virus (JCV) and Powassan virus (POW), 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.

"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. 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.

Powassan virus infection is similar to mosquito-borne viruses like JCV, West Nile virus (WNV), and Eastern equine encephalitis (EEE), but is transmitted to people by infected ticks. POW was identified as a cause of human illness in the late 1950’s. In the last decade, 144 cases of POW have been detected in the United States. This is New Hampshire’s fourth case of POW, also since 2013. In New Hampshire, the blacklegged tick is the most likely to transmit this virus to people. A tick needs to be attached to a person for only 15 minutes to transmit POW. Some people who are infected may experience mild illness or no symptoms. Powassan virus can also infect the central nervous system causing brain inflammation, which may be disabling or fatal.

The Kingston resident had no recent history of travel outside our state and spent a great amount of time outdoors. Residents and visitors to New Hampshire should protect themselves and their family members by:

• using an effective mosquito and tick repellant containing DEET (20-30%), Picaridin, or oil of lemon eucalyptus
• wearing protective clothing, tucking shirts into pants and pants into socks
• removing standing water from around your house so mosquitoes do not have a place to breed
• being mindful of tick habitat keeping grass cut short, and
• performing frequent and daily tick checks with immediate tick removal.
• Vitamin B, ultrasonic devices, incense, and bug zappers have not been shown to be effective in preventing mosquito- or tick-borne diseases.

Other mosquito- and tick-borne illnesses that have been documented in New Hampshire include WNV and EEE from mosquitoes, and Lyme disease, anaplasmosis, babesiosis, and Borrelia miyamotoi from ticks. Biting mosquitoes will continue to be a disease concern until there are two, statewide, hard frosts. Risk of tick bites exists when temperatures are above freezing and ticks are not covered by snow.

People can be infected and 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 infected with JCV, EEE, WNV, and Powassan can develop more serious central nervous system disease, including meningitis or encephalitis. If you or someone you know is experiencing flu-like symptoms, including fever and headache, contact your local medical 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 between 8 AM to 4:30 PM, Monday through Friday. More information can also be found online www.cdc.gov.