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

Macomb County has its first case of West Nile virus in mosquitoes this summer, health officials announced on Thursday. The virus was detected in a single sampling of mosquitoes gathered in Macomb County, officials said. No confirmed human cases of the virus have been reported in Michigan so far.

There have been no cases of human West Nile Virus cases this year in Michigan, but the virus is endemic in Macomb County, meaning it is regularly found in mosquito populations here.