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DHHS Identifies Positive Test Result for West Nile Virus: First Positive Mosquito Batch of the Season
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Bureau of Infectious Disease Control
Publish Date:
September 16, 2015

Concord, NH – The New Hampshire Department of Health and Human Services (DHHS) is announcing that a batch of mosquitoes has tested positive for West Nile Virus (WNV) recently from the city of Manchester. This is the first mosquito batch found to be positive so far this year and the first positive test result of the season. DHHS is collaborating with the City of Manchester Health Department on notification around this recent detection.

WNV, along with Eastern Equine Encephalitis (EEE), are arboviruses that are transmitted from the bite of an infected mosquito. WNV was first identified in New Hampshire in August of 2000. The Public Health Lab has tested 3,048 mosquito batches, two animals, and 46 people so far this season for WNV and EEE. There have been no positive tests for EEE yet this year. Last year, 1 mosquito batch tested positive for WNV in New Hampshire and there were 18 positive batches for EEE. No animals tested positive for WNV last year but there were three EEE positive animals. Three humans were determined to have been infected with EEE last year as well, with two fatalities, but there were no people found infected with WNV.

"This is the first positive mosquito test result in New Hampshire this season," said NH State Epidemiologist Dr. Benjamin Chan, "NH residents and visitors need to make sure they take precautions to prevent being bitten by mosquitoes as we head into the fall, the most risky time of year for mosquito-borne illnesses like WNV and EEE."

Residents and visitors to New Hampshire should protect themselves and their family members by using an effective mosquito repellant that contains 30% DEET, wearing long sleeves and pants at dawn and dusk when mosquitoes are most active, and removing standing water from around your home so mosquitoes do not have a place to breed. Repellents with picaridin, IR3535 and some oil of lemon eucalyptus and para-menthane-diol products also provide protection against mosquito bites.

Symptoms of the WNV usually appear within a week after being bitten by an infected mosquito, although many people can be infected and not develop any symptoms, or only develop very mild symptoms. Symptoms can include flu-like illness including fever, muscle aches, headaches, and fatigue. A very small percentage of individuals infected with WNV can go on to 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 WNV/EEE can call 1-866-273-6453 between 8 AM to 4:30 PM, Monday through Friday. Other information about EEE and West Nile virus are available on the DHHS website at and on the Centers for Disease Control and Prevention website at

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New Hampshire Department of Health and Human Services
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