KALAMAZOO, Mich. (WOOD) — There has been a second detection of West Nile virus in a group of female mosquitoes in Kalamazoo County, the Kalamazoo County Health & Community Services Department’s Environmental Health Division said.

Michigan has tested 3,500 mosquito pools this year; 43 of them have had positive tests for West Nile virus. Kalamazoo County’s first positive test was in July.

According to the U.S. Centers for Disease Control and Prevention, West Nile virus is the leading cause of mosquito-borne disease in the U.S. While some infected with the disease may not show any signs of sickness, about one in five people develop mild flu-like symptoms.

“Positive results from routine mosquito surveillance remind us that the threat for these diseases is very much real and that preventative measures should be taken seriously,” Kalamazoo County Environmental Health Manager Lucus Pols said in a press release.

No people in Michigan have tested positive for West Nile this year, state data from Aug. 18 shows, but two in the Detroit area have contracted the mosquito-borne Jamestown Canyon virus. In Bay and Barry counties, three mosquito pools have tested positive for Eastern Equine Encephalitis, another mosquito-borne illness.

You can protect yourself from West Nile and other illnesses by using insect repellents, protective clothing, staying indoors when mosquitos are most active, and dumping standing water around your home.

The Environmental Health Division will continue mosquito surveillance and testing until the end of September.