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Home > Community Services > Public Health Programs > West Nile Virus Information

West Nile Virus Information and Resources


       PDF  West Nile Virus Response Plan for the National Capital Region (2003)


On behalf of the Metropolitan Washington Council of Governments (COG) Health Officers Committee, welcome to the COG West Nile Virus (WNV) Web site. The purpose of this Web site is to increase awareness and provide access to resources (local, state, and national) on WNV for residents of the Washington metropolitan area. In addition, this Web site will provide information about what is being done locally on West Nile Virus.

The General Information section provides an overview of WNV, symptoms and treatment of WNV, steps that the public can take to keep their families and community safe, and where to call if a dead bird is found in your area. To keep the public informed about what steps local health officials are taking regarding WNV, there is a link to the COG West Nile Virus Response Plan.

If you would like to know how to contact your local health department, please visit the Local Information page. Each health jurisdiction represented by COG has provided a telephone number or web site where you can find out what is being done in your area regarding WNV.

On the Educational Information page, there are links to the Centers for Disease Controland Prevention (CDC), to local information for your county, and links to agencies (state and federal) that may answer your questions about pesticides. The CDC answers questions to a variety of topics, such as Prevention of WNV, WNV and Birds, etc.

The Additional Resources page lists federal and academic institutions that provide additional information about WNV and related topics.

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Q:  What is West Nile Virus infection? 
A:  The West Nile Virus infection is one that is spread by the bite of infected mosquitoes. It usually causes a mild illness, but may also cause encephalitis (inflammation of the brain) or meningitis (inflammation of the lining of the brain and spinal cord). This virus is named after the West Nile region of Uganda where the virus was first isolated in 1937. It caused an outbreak in New York in 1999.

Q:  Who gets West Nile virus infection? 
A:  Anyone can get West Nile Virus infection if bitten by an infected mosquito; however, even in areas where transmission of West Nile Virus is known to be occurring only a small proportion of mosquitoes are likely to be infected, much less than 1%. Even if an infected mosquito bites a person, the chance of developing serious illness is approximately less than 1%. Persons who have weakened immune systems and the elderly are at greater risk of developing a more severe form of the illness.

Q:  How is West Nile Virus spread? 
A:  Infected mosquitoes spread West Nile Virus. Biting a bird that carries the virus infects a mosquito. West Nile Virus is not spread from one person to another or directly from birds to humans.

Q:  Do all mosquitoes bite humans? 
A:  No, only adult female mosquitoes bite humans. Male mosquitoes feed on plant juices only. Most female mosquitoes feed on humans, birds and other animals to get sufficient blood to develop eggs.

Q:  Do all mosquitoes transmit the West Nile Virus
A:  While there are many species of mosquitoes, the adult Culex pipiens mosquito (the common house mosquito) is the one most commonly associated with the West Nile virus.

Q:  Why are some people bitten more than others? 
A:  There are many factors. Cologne, perfumes and scented body lotions can attract mosquitoes. Dark colored clothing is also more attractive to mosquitoes. During evenings, nighttime and dawn, mosquitoes are most active in searching for blood, so people outdoors during that time are more likely to be bitten. Finally, everyone's body is different, and some people produce odors more enticing for mosquitoes.

Q:  Where do mosquitoes live? 
A:  The Culex pipiens mosquito (the common house mosquito) lays its eggs in standing water around the home. Weeds, tall grass, and bushes provide an outdoor home for the adult Culex pipiens mosquito.

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Q:  I have gotten a mosquito bite. Should I be tested for West Nile Virus infection?
A:  No, most mosquitoes are not infected with West Nile Virus. See a physician if you develop the symptoms below.

Q:  What are the symptoms of West Nile Virus infection? 
A:  The disease may be mild or serious. Mild illness includes fever and muscle aches, swollen lymph glands and sometimes a skin rash. In the elderly, infection may spread to the nervous system or bloodstream and cause sudden fever, intense headache, and stiff neck and confusion, possibly resulting in encephalitis or meningitis. Healthy children and adults may not have any symptoms.

Q:  How soon after exposure do symptoms appear?
A:  The symptoms generally appear about 3 to 6 days after exposure but may appear as soon as 1 day after exposure or as late as 7 or more days.

Q:  Does past infection with West Nile Virus make a person immune?
A:  Yes, a person who gets West Nile Virus probably cannot get it again.

Q:  What is the treatment for West Nile Virus infection?
A:  There is no specific treatment. Supportive therapy will be used in more severe cases. Most people recover from this illness.

Q:  Is there a vaccine for West Nile Virus?
A:  There is no vaccine.

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Controlling mosquitoes or eliminating mosquito-breeding sites around the home can prevent West Nile infection.

1.  Avoid getting mosquito bites by using insect repellants and by wearing protective clothing.

2.  Another way to control mosquitoes is to remove standing water where mosquitoes breed.

  • Remove or change water twice a week in anything that collects water around your home. This includes cans, birdbaths, pet dishes, toys, tires, flower pots, pools.
  • Clean clogged roof gutters and downspout screens regularly.
  • Turn over wheelbarrows, canoes and plastic wading pools when not in use.
  • Dispose of discarded tires properly.
  • Drill drainage holes in tires used for playground equipment.
  • Eliminate standing water on flat roofs. Do not leave trashcan lids upside down.
  • Do not allow water to collect in the bottom of trashcans.
  • Adjust tarps over grills, firewood piles, boats and swimming pools to eliminate standing water.
  • Re-grade drainage areas and clean out debris in ditches to eliminate standing water in low spots.
  • Clean and chlorinate swimming pools.
  • Aerate garden ponds.
  • Fix leaky water faucets and eliminate condensation puddles around air conditioners.
  • Store pet food and water bowls indoors when not in use.

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Dead birds act as a sentinel and dead bird surveillance is one of the components of Integrated Pest Management for West Nile virus. The District of Columbia and Maryland have determined that West Nile virus is now endemic in their jurisdictions and are no longer studying dead birds. If you find a dead bird in the District or Maryland, please dispose of the bird yourself (See Appendix E in the West Nile Virus Response Plane for the National Capital Region for protocol).

In 2003, Virginia will continue to monitor, and in some cases test, dead birds reported to local health departments. Only selected crows, blue jays and raptors (i.e. hawks, falcons or owls) will be tested for mosquito-borne viruses, because they are the best early signs of virus activity in an area. However, once a certain number of positive birds are identified in a locality, testing may cease except for special circumstances.

In Virginia, contact your local health department to determine whether the bird should be submitted for laboratory testing, or visit the Virginia Department of Health Web site for more information.

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