West Nile Virus Facts

To report sick or dead birds and mammals to the State, click here.

West Nile Encephalitis

Viruses and bacteria can cause encephalitis [an inflammation of the brain] or meningitis [inflammation of the lining of the brain and spinal cord]. Many individuals infected with the virus do not become ill, however, in those who become ill, most infections are mild. In 1999 and 2000, it caused an outbreak of human encephalitis in and around New York City. It is not known how West Nile was introduced in the United States.

Natural Transmission

Infected mosquitoes are the primary source for West Nile Virus. Mosquitoes become infected with West Nile Virus when they feed on infected birds that carry the virus in their blood. Those infected mosquitoes can then transmit West Nile Virus to humans and other animals while biting them to take in blood. West Nile encephalitis is not transmitted from person-to-person.

Signs & Symptoms

Most infections are mild, and symptoms include body aches, skin rash and swollen lymph glands. More severe infection may be marked by headache, high fever, stiff neck, stupor, disorientation, coma, tremors, convulsions, muscle weakness and paralysis. Persons with severe or unusual headaches should seek medical care as soon as possible.

Risk

Everyone is susceptible to West Nile encephalitis or meningitis in areas where virus activity has been identified; however, less than 1% of people who get bitten by an infected mosquito will become severely ill.

Treatment

There is no vaccine for West Nile encephalitis. However, a person with severe disease, intensive supportive therapy is indicated: hospitalization, intravenous fluids, airway management, respiratory support (ventilator) if needed, prevention of secondary infections (pneumonia, urinary tract, etc.), and good nursing care.

How to Prevent Infection

• Empty all sources of standing water such as birdbaths, old tires and toys where water can collect.
• As much as possible, stay inside when mosquito activity is heavy-dawn, dusk and early evening.
• Whenever possible, wear long sleeves and long pants.
• Close gaps and cracks in window screens.
• Use insect repellent containing permethrin or DEET. An effective repellent will contain 35% DEET. The American Academy of Pediatrics recommends products with 10% or lower DEET for children.
• Do not use products with DEET on infants. Apply repellent on exposed skin and clothes. Do not place on child's hands or near mouth.
• Wash repellent off after coming indoors.

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West Nile Virus Hotline Number

American crows are susceptible to West Nile Virus infection. Therefore, crows, ravens and blackbirds found dead less than 48 hours should be reported to the Michigan Department of Community Health’s hotline number at 888-668-0869, or access the State's west nile virus web site at www.michigan.gov/westnilevirus.

*Information provided by the Centers for Disease Control and Prevention

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