West Nile virus found in metro-Detroit mosquitoes

West Nile reported near Detroit

DETROIT - Health technicians in both Wayne and Macomb counties said Tuesday they’d found recent samples of mosquitoes infected with the West Nile virus.

Oakland County health officials said they turned up infected mosquitoes last month.

And the counties' health experts said now's the time to beware of the bugs' bite because prevalence of the virus peaks each year in Michigan from late July through September.

Although cases in humans usually pass unnoticed by those who contract it, the disease can be fatal in elderly persons and others with weak immune systems, said William Ridella, health officer and director of Macomb County Health Department.

Mosquitoes infected with the virus transmit it to humans when they bite, Ridella said. The discovery of infected insects is “a reminder that West Nile is in our area,” he said Tuesday. 

Michiganders should use mosquito repellents, and look for the active ingredient DEET; wear long sleeves and long pants if they’re spending much time outdoors, and be aware that mosquitoes are most active at dawn and dusk, Ridella said.

“We trap mosquitoes in the more populated areas of the county, mainly south of M-59, and two of our traps over the weekend came back positive with West Nile virus,” he said. Ridella declined to say in what communities the infected mosquitoes were found, to avoid unnecessarily alarming residents there, he said.

West Nile virus first turned up in southeast Michigan about 15 years ago, “and the best advice is just take the proper preventive measures,” Ridella said. Prevention includes getting rid of standing water – “anything from old buckets and barrels to planters and old tires” — to prevent mosquitoes from breeding, he said.

“And make sure your doors and screens are in good condition," so the insects can’t get in, he said. Last year, Michigan had 43 cases of the West Nile virus identified in humans, and the disease was blamed for three deaths, according to the Michigan Department of Health and Human Services.

On Tuesday, Wayne County technicians found "our first positive mosquito" infected with the virus, Carol Austerberry, the county's deputy health director, said in an e-mail.

In Oakland County, technicians found a sample of infected mosquitoes in early July, said Tony Drautz, administrator of the Environmental Health Section in the Oakland County Health Division.

Adults should be cautious when applying repellents to young children, as the chemicals "may irritate the eyes and mouth," Drautz said Tuesday. 

The division’s website has this about symptoms:

  • Serious cases. About one in 150 people infected with the West Nile virus will develop severe illness. Symptoms include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. Symptoms may last several weeks, but neurological effects can be permanent. 
  • Mild cases. Up to 20% of infected humans may exhibit fever, headache, body aches, nausea, vomiting, and sometimes swollen lymph glands or a skin rash on the chest, stomach and back. Symptoms usually last only a few days, although some people fall ill for several weeks.
  • No symptoms. About 80% of those infected with the virus display no symptoms.

According to the U.S. Centers for Disease Control and Prevention, a mosquito becomes infected with the West Nile virus if its bites a bird infected with the virus. The virus can infect horses and other mammals as well as humans and birds, the agency’s website says.

Contact Bill Laitner: blaitner@freepress.com

© 2017 Detroit Free Press


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