West Nile Virus has been confirmed for the first time this summer among mosquitoes in Macomb County, health officials said.

DENVER ( KDVR) — The first trace of the West Nile virus this season was found in Denver through a positive mosquito sample. On Thursday, the Denver Department of Public Health & Environment announced that the virus was found through routine mosquito sample testing. This marks the first detection of the season for the city.

Most West Nile cases in Colorado happen between July and September, though mosquitoes can live until the first snow or hard freeze.