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First human cases of West Nile virus for 2017 confirmed in Michigan
Activity is high throughout the State


Aug. 31, 2017

LANSING – The Michigan Department of Health and Human Services today confirmed the state’s first human cases of West Nile virus for 2017.  Four cases of WNV have been confirmed; two residents of Montcalm County, and one each from Oakland and Macomb Counties.  Their illness onsets range from August 6 to 11, and all have been hospitalized with neurologic disease.


“This is an important reminder to stay vigilant and protect against mosquito bites throughout the summer and into the fall,” said Dr. Eden Wells, Chief Medical Executive at the MDHHS.  “All residents should take steps to prevent bites, such as use repellent and take extra care during peak mosquito-biting hours between dusk and dawn.”


Surveillance for mosquito-borne diseases is being conducted by the MDHHS and Departments of Natural Resources and Agriculture and Rural Development.  In 2017, WNV activity appears to be widespread statewide in Michigan. In addition to the four human cases, five Michigan blood donors have had WNV detected in their blood.


To date, 148 birds have tested positive for WNV from 44 of Michigan’s 83 counties.  In addition, 86 WNV positive mosquito pools have been detected in seven Michigan counties. MDARD has reported eight horses that have tested positive for WNV (Clinton, Jackson, Livingston, Missaukee, Mecosta, Midland, Ottawa, and Wexford Counties). Also one horse has tested positive for Eastern Equine encephalitis virus (Wexford County). Vaccination is the best way to protect horses from both WNV and EEE. Horse owners should work with their veterinarian to make sure their horse is properly vaccinated. Finding infected birds, mosquitoes and horses in a community is an indication of risk for human infection.


Most people who become infected with WNV will not develop any symptoms of illness. However, some become sick three to 15 days after exposure. About one-in-five infected persons will have mild illness with fever, and about one in 150 infected people will become severely ill.


Mild illness may include headache, body aches, joint pain, vomiting diarrhea, or rash. Severe symptoms of WNV are associated with encephalitis or meningitis, and may include: stiff neck, stupor, disorientation, coma, tremors, muscle weakness, convulsions and paralysis. People 50 and older are more susceptible to severe WNV disease symptoms.


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


  •     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.

  •     Use nets and/or fans over outdoor eating areas.

  •     Apply insect repellents that contain the active ingredient DEET, or other EPA approved product 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.


For more information and surveillance activity about West Nile virus and other mosquito-borne viruses, visit

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