(Chelsea Update would like to thank Susan Ringler-Cerniglia for the information in this story.)
Washtenaw County Health Department reminds local residents to prevent mosquito bites as mosquitoes collected in Washtenaw County last month have tested positive for West Nile virus (WNV). No human cases have been reported.
But, the best way to prevent infection is to avoid mosquito bites.
“Our local mosquitoes can spread serious illnesses,” says Laura Bauman, MPH, epidemiology program manager with the Washtenaw County Health Department in a press release. “We haven’t had a human case of West Nile in Washtenaw since 2018, but we’re nearing the time of year when human cases are more likely in Michigan. Late summer is a great time to enjoy the outdoors, but please take steps to prevent mosquito bites.”
Most people infected with West Nile do not become ill or only experience mild illness. In rare cases, infections can become serious. The Health Department does not recommend avoiding the outdoors but urges precautions. Use appropriate repellant, wear protective clothing, and avoid areas with mosquito activity when possible.
These WNV-positive samples were identified in Ypsilanti. In previous years, WNV-positive mosquitoes have been identified in areas throughout the county. Additionally, three local birds in southern Washtenaw County have tested positive for WNV so far this summer, providing further evidence that the virus is circulating in our local wildlife.
The Health Department collects and identifies mosquitoes to understand local disease risk and contribute data to the statewide tracking system. This surveillance will continue throughout the summer while mosquitoes are active.
West Nile virus
So far this year, there have been 2 reported cases of human WNV in Michigan. Last year, 24 Michigan residents tested positive for WNV.
Most people infected with West Nile virus have no symptoms of illness, but some may become ill 3 to 15 days after the bite from an infected mosquito. About 1 in 4 people infected will experience mild illness with fever, headache, and body aches, sometimes with a skin rash and swollen lymph glands.
Less than 1% of people who get bitten and become infected with West Nile virus will develop a severe illness like encephalitis or meningitis. The risk of getting West Nile encephalitis is higher in people 50 or older. More severe infection may be marked by convulsions, disorientation, headache, high fever, muscle weakness, stiff neck, or paralysis. In a few cases, mostly among the elderly, death may occur.
Prevention
Avoiding mosquito bites is the best way to prevent mosquito-borne diseases:
Apply insect repellents that contain the active ingredient DEET or other EPA-approved products to exposed skin or clothing. Follow the manufacturer’s directions for use.
Wear light-colored, long-sleeved shirts and long pants when outdoors. Apply insect repellent to clothing to help prevent bites.
Maintain window and door screening to help keep mosquitoes outside.
Empty water from mosquito breeding sites around the home, such as buckets, kiddie pools, and other water-holding containers where mosquitoes can lay eggs.
Resources
Environmental Protection Agency’s Insect Repellent Search Tool
Michigan Department of Health and Human Services www.michigan.gov/emergingdiseases
Michigan Department of Agriculture & Rural Development’s list of licensed pesticide control businesses
Washtenaw County Health Department’s mosquito-related illnesses webpage
