Health officials: Viruses found in NH mosquitoes, ticks

EXETER — State health officials and pest control experts are reminding area residents to stay vigilant after a Kingston man contracted two viruses transmitted by ticks and mosquitoes.

The state Department of Health and Human Services announced Aug. 8 a man tested positive for both the Jamestown Canyon virus (JCV) and Powassan virus (POW). JCV is transmitted by infected mosquitoes and POW by infected ticks. DHHS officials said the Kingston man had not recently traveled outside the state, but noted he spends a “great” amount of time outdoors.

State Epidemiologist Dr. Benjamin Chan said New Hampshire residents and visitors are at risk from spring until fall of getting infections from mosquitoes and ticks.

"This case highlights the risk from both," Chan said, adding there are a number of other viral and bacterial infections that can be transmitted by mosquitoes and ticks in New Hampshire. "We recommend that residents and visitors continue to take basic steps to prevent mosquito and tick bites in order to stay healthy."

News of the Kingston man was followed Tuesday by an announcement from DHHS of mosquitoes carrying Eastern equine encephalitis (EEE) collected in Pelham. A second announcement came Wednesday by Manchester city officials of two batches of mosquitoes testing positive for EEE, those batches having been collected Aug. 8.

No human cases of EEE have been reported in New Hampshire yet this year. People who get sick from EEE can develop a flu-like illness, including fever, headache, weakness and muscle and joint pains, though a more serious central nervous system infection can develop such as meningitis and encephalitis, or inflammation of the brain.

Chan said the identification of the EEE virus in mosquitoes in New Hampshire is an important reminder that mosquito bites can transmit a number of potentially serious viral infections. He said people need to take steps to prevent mosquito bites, including avoiding being outdoors at dawn and dusk when mosquitoes are most active. He advised wearing protective clothing, using an effective mosquito repellent on exposed skin and removing standing water from around the home where mosquitoes reproduce.

JCV is a mosquito-borne pathogen that circulates widely in North America primarily between deer and mosquito species but can infect humans. Officials said this was the state’s seventh case of JCV but the first reported since 2013. Illnesses caused by JCV are typically mild but the virus can also cause moderate to severe central nervous system damage.

“All the mosquito-borne pathogens, EEE, Jamestown Canyon and the West Nile virus, all present similar flu-like symptoms with fever, chills, general weakness," Chan said. "They can all lead to nervous system infections."

Chan said part of the reason the state is seeing more of these other viruses is because they are testing more. He said blood specimens with EEE sent to the Centers for Disease Control and Prevention have been shown to have JCV sample as well.

“That’s consistent with other states that have done more testing," Chan said.

He said POW can also present symptoms similar to the mosquito-borne infections. In the last decade, 144 cases of POW have been identified in the United States and last week’s discovery marked the state’s fourth case since 2013, DHHS officials said. Some people infected may experience mild illness or no symptoms, however, POW can infect the nervous system causing brain inflammation and could be fatal or result in long-term nervous system damage, Chan said.

To combat the risk of tick-borne illnesses, Chan recommended individuals and families perform daily tick checks on themselves and their pets.

“We’re still learning about how these viruses present,” he said. “There are no specific treatments or a way to prevent infections and complications other than preventing bites.”

Sarah MacGregor, president of Dragon Mosquito of Brentwood said the weeks as summer transitions to fall present the highest risk of contracting vector-borne viruses. Her company is contracted to spray mosquito-killing insecticides in nearly two-dozen New Hampshire communities, including Brentwood, Hampton, North Hampton, Stratham and Seabrook.

MacGregor recommended area residents limit outdoor activities when possible but when outside, they should be wearing long pants and long sleeves and using insect repellent. She said pathogens build up in the insect and bird population over the summer, then spill over to the human population late in the summer.

“The risk is not over until the first freezing event," MacGregor said. "I don’t breathe a sigh of relief until there’s snow on the ground.”

Chan said communities that collect mosquito samples help inform public health officials on the prevalence of infected insects in an individual community.

“It helps communities inform the level of risk,” he said. “Just because we identify a mosquito sample with EEE, it doesn’t mean people will come down with infections.”