The health department in the city of Portsmouth says a batch of mosquitoes has tested positive for Eastern Equine Encephalitis, a rare disease that can be transmitted to humans.
Health officials say EEE is expected to be found during late summer and fall in local mosquitoes.
Officials say street spraying will continue as planned and treatment of parks, playgrounds and athletic fields started last week. But they say the best prevention is by protecting yourself and family from being bitten by an infected mosquito.
Officials advise using insect repellent and wearing long sleeve shirts and pants, weather permitting.
At least two people in New Hampshire have contracted EEE this summer.
Symptoms include fever, headache, stiff neck and sore throat but severe cases can lead to encephalitis or death.