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Health Department

Health Department

West Nile Virus


Tell me more about West Nile.

West Nile virus was recently introduced to the United States in 1999, when it started causing deaths in birds and illness in humans in New York City. West Nile is classified as a flavivirus, which is in the same family as Hepatitis C, dengue, and yellow fever.

How is West Nile spread?

West Nile is a vector-borne disease, carried by the mosquito. The majority of the mosquito species living in the US are capable of transmitting West Nile. Mostly, West Nile infects birds, especially corvids (crows and jays), and tends to cause severe mortality (death) in birds when it reaches a new area. Humans appear to be incidental hosts; that is, the West Nile disease cycle is complete without humans, and West Nile tends to be transmitted to people by the bird => mosquito => human pathway, rather than a mosquito transmitting the disease between humans.

What are the symptoms of West Nile?

Most people (80%+) infected with West Nile virus will show no symptoms at all, while the majority who do show symptoms will develop West Nile fever. West Nile fever is characterized by non-specific symptoms such as body aches, fatigue, and myalgia (not feeling well). These symptoms can last for as short as several days to as long as several weeks. A small minority will develop West Nile meningitis and encephalitis (WNME), which occurs when the virus infects the brain and surrounding tissues. People suffering from meningitis and/or encephalitis tend to have the following symptoms:

  • High fever
  • Headache
  • Stiff neck
  • Stupor
  • Disorientation
  • Coma
  • Tremors
  • Convlusions
  • Muscle weakness
  • Paralysis

This is most likely to occur in persons over the age of 50.

What are the treatments for West Nile virus?

Currently, there are none. Antiviral agents were found to be ineffective since they did not cross into the brain where the virus was replicating. Treatment for ill persons involves supportive care, such as intravenous fluids and breathing assistance, such as ventilation.

How can I prevent West Nile virus?

There are several steps you can take to reduce the chance you will be bitten by a mosquito and go on to contract West Nile disease.

  • Destroy mosquito habitats by removing all standing water in your yard and around your house. This includes birdbaths, water in tires, pet dishes, and other areas in which water can collect. If the water cannot be removed, change it frequently- at least once a week.
  • Avoid going outside during peak mosquito activity hours, from dusk until dawn.
  • Wear an effective mosquito repellant such as one that contains DEET, which has been proven to reduce the number of mosquito bites. Higher concentrations of repellant should be used for longer lengths of time you will be exposed to mosquitoes. Be sure to follow the manufacturer's directions when using any insect repellant.
  • Wear protective clothing when outside, such as long sleeves, long pants, and socks.

A vaccine for West Nile virus is currently under development, but is not ready yet.

What should I do if I find a dead bird?

Do NOT touch the bird with your bare hands! Call the Monroe County Health Department at (734) 240-7800 to report the bird, and county officials will take care of it or give you instructions for proper disposal.

CDC Info on West Nile virus:


Michigan West Nile virus site:


Other Links on West Nile and Mosquito Control:

Environmental Protection Agency (EPA)

U.S. Geological Survey National Wildlife Health Center

US Geological Survey West Nile Maps

National Pesticide Telecommunications Network

Michigan Mosquito Control Association (MMCA)