CONCORD — Over the past week, the New Hampshire Department of Health and Human Services has announced three disease-causing viruses that they have found to be active in the state, two carried by mosquitoes and the other by ticks.

On Tuesday, the department announced it had identified the first batches of mosquitoes to test positive for Eastern Equine Encephalitis this season.

The batches were found in the town of Pelham, and DHHS is working in partnership with health officers there and in surrounding towns to notify residents.

EEE is one of three mosquito-transmitted diseases present in New Hampshire, including West Nile Virus and Jamestown Canyon virus, and was first identified in the state in August 2004. Fifteen human infections have been reported since that time in the state. The last human cases of EEE in N.H. (three) were in 2014. There have been no EEE infections identified yet this season in humans or animals.

On Aug. 9, DHHS announced an adult from Kingston tested positive for both Jamestown Canyon virus and Powassan virus. Jamestown Canyon is transmitted by infected mosquitoes and Powassan by infected ticks. There are no vaccines to prevent either disease.

State Epidemiologist Dr. Benjamin Chan said both reports highlight the risks of infection and the importance of taking preventative steps.

“People need to take steps to prevent mosquito bites, including avoiding being outdoors at dawn and dusk when mosquitoes are most active, wearing protective clothing, using an effective mosquito repellant on exposed skin, and removing standing water from around the home where mosquitoes reproduce,” he said.

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 Jamestown Canyon virus since the first report of the disease in 2013. Most reported illnesses caused by Jamestown Canyon virus have been mild, but moderate-to-severe central nervous system involvement has been reported.

Powassan virus infection is similar to mosquito-borne viruses like Jamestown Canyon virus, West Nile virus, and Eastern equine encephalitis, but is transmitted to people by infected ticks.

Powassan was identified as a cause of human illness in the late 1950s. In the past decade, 144 cases of Powassan have been detected in the United States. This is New Hampshire’s fourth case since 2013.

In New Hampshire, the black-legged 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.

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 percent), 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.

• 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 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 and joint pain, headaches, weakness and fatigue.

People infected with JCV, EEE, WNV, and Powassan can develop more serious central nervous system disease, including meningitis or encephalitis (inflammation of the brain).

EEE typically causes a more serious disease than WNV and carries a high mortality rate for those who contract the serious encephalitic form of the illness. Symptoms of EEE virus usually appear four to 10 days after being bitten by a mosquito carrying the EEE virus. There is no specific treatment for the disease.

Powassan virus can also infect the central nervous system and can be disabling or fatal.

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 a.m. and 4:30 p.m., Monday through Friday. More information can also be found online

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