This 2003 photo provided by the Centers for Disease Control and Prevention shows a mosquito acquiring a blood meal from a human host. Credit: James Gathany | Centers for Disease Control and Prevention via AP

CONCORD, New Hampshire — The New Hampshire Department of Health and Human Services has identified the first batch of mosquitoes this year to test positive for West Nile Virus.

The department said the batch was collected in Manchester on Aug. 21.

DHHS is working with the city of Manchester Health Department to notify Manchester residents and those in the surrounding towns of the positive West Nile Virus test.

State Epidemiologist Benjamin Chan said until there’s a statewide mosquito-killing frost, the risk of infection by mosquito-borne viruses will increase.

West Nile Virus was first identified in New Hampshire in 2000. Symptoms usually appear within a week after being bitten and can include flu-like illness, including fever, muscle aches, headaches, and fatigue. Many people may not develop any symptoms, or only develop very mild symptoms.