First Human West Nile Virus Case Found In Michigan

MICHIGAN — Michigan officials have confirmed the first human West Nile Virus infection in 2018 after a blood donor tested positive for the mosquito-borne virus in Sanilac County, located in Michigan's thumb region.

“This is an important reminder to stay vigilant and protect against mosquito bites throughout the summer and into the fall,” said Dr. Eden Wells, Michigan Department of Health and Human Services chief medical executive. “Residents should use insect repellent, drain standing water around the home and take extra care during peak mosquito-biting hours between dusk and dawn.”

Blood donations are screened for West Nile prior to distribution, to ensure that the blood supply is safe from the virus. Blood donations that test positive for West Nile virus are discarded and not used for transfusions.

According to officials, the donor is not reporting any illness. Most people who become infected with West Nile virus will not develop any symptoms. However, some become sick three to 15 days after exposure.

About one in five infected persons will have mild illness which may include fever, headache, body aches, joint pain, vomiting diarrhea or rash. About one in 150 infected people will become severely ill. Severe symptoms of WNV are associated with encephalitis or meningitis, and may include a stiff neck, stupor, disorientation, coma, tremors, muscle weakness, convulsions and paralysis. People 60 and older are more susceptible to severe WNV disease symptoms.

Bites from Culex pipiens, or the northern house mosquito, are the primary cause of the West Nile Virus human infections in Michigan. The mosquitoes become infected with West Nile Virus when they bite an infected bird. Hot weather is favorable for mosquitoes, shortening the time for them to develop from egg to adult, and small pools of stagnant water provide the perfect habitat for Culex mosquitoes to lay eggs.

To date, 20 birds and 24 mosquito pools have tested positive for West Nile in Michigan. Visit Michigan.gov/westnilevirus to find maps of current West Nile Virus activity in Michigan by county.

Residents can stay healthy by using simple, effective strategies to protect themselves and their families. The following steps are recommended to avoid West Nile Virus and other mosquito-borne diseases:

• Apply insect repellents that contain the active ingredient DEET, or other EPA-approved products to exposed skin or clothing, and always following 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, unused kiddie pools, old tires or similar sites where mosquitoes lay eggs.

For more information and surveillance activity about West Nile virus and other mosquito-borne viruses, visit Michigan.gov/westnilevirus.

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