September 1, 2014 at 10:16 am

No human cases of West Nile in Michigan yet

East Lansing— West Nile virus, an annual health threat for more than a decade, so far hasn’t been detected in Michigan residents, likely because of a cool summer, an expert says.

The state recorded 202 cases, including 17 deaths, just two years ago. But 2014 is turning out to be virus-free, at least among humans, according to the Department of Community Health.

There were 36 cases last year, including two deaths.

“We should anticipate very few if any human cases in Michigan,” said Ned Walker, an entomologist at Michigan State University. “We always have a few by the end of any summer, but we are not in outbreak conditions right now. Rather, the opposite.”

The Macomb County Health Department on Aug. 21 said in a news release it had detected the virus in mosquitoes in Fraser, the first positive sample this year. It cautioned residents to avoid mosquito bites and to reduce mosquito breeding grounds.

A snowy winter and wet spring might lead to more mosquitoes, the carrier of West Nile. But that doesn’t automatically translate into a greater risk for getting the virus.

Walker said the virus needs hot weather to become potent. Since June, the National Weather Service reports only three days of 90 degrees or higher at Detroit Metropolitan Airport, through Friday.

Mosquitoes pick up the virus from infected birds and then pass it to people. The elderly and people with a weak immune system are considered to be at greatest risk for death.

“Fortunately, most people infected with WNV will have no symptoms,” the U.S. Centers for Disease Control and Prevention said on its website. “About one in five people who are infected will develop a fever with other symptoms. Less than 1 percent of infected people develop a serious, sometimes fatal, neurologic illness.”

Michigan was the only state in the Midwest without a human case, through Aug. 26, the CDC reported. At least 12 people in the U.S. have died this year.

The Detroit News contributed.