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 | CDC via AP

ESSEX, Vermont — The Vermont Department of Health said a pool of mosquitoes collected in Essex has tested positive for West Nile virus.

The department said Friday that more than 2,000 mosquito pools — or groups of up to 50 mosquitoes of the same species and location — have been tested this year around Vermont. This is the first one to test positive for the virus, which is spread to humans by the bite of an infected mosquito.

The Health Department said most people do not develop any symptoms, which can include fever, headache, body aches, joint pain, vomiting, diarrhea and skin rash.

West Nile virus has been found in mosquitoes in every county in Vermont in the past. The Health Department said 12 cases have been reported in Vermont residents since 2011.