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Diseases and conditions
West Nile virus

What is the current status of West Nile Virus in Clark County?

Frequently asked questions

- What is West Nile virus?
- How is it spread?
- What are the symptoms?
- How is it treated?
- What can be done to prevent infection?

Protect yourself and your family:
- How can I protect myself from West Nile virus?
- How can I prevent mosquito bites?
- How do I report dead birds?

Health care providers, hospitals, laboratories and veterinarians

What is West Nile virus?
West Nile Virus is a mosquito-borne virus first found in the United State in 1999 when it caused illness in New York City. It is commonly found in West Asia, Africa, and the Middle East. The virus can infect people, certain types of birds, mosquitoes, horses and other animals. Only certain species of mosquito carry the virus.

How is it spread?
West Nile Virus is spread by the bite of an infected mosquito. Mosquitoes become infected when they feed on infected birds. After 10 to 14 days, the infected mosquito can transmit West Nile Virus to people and animals through its bite. West Nile virus is not spread from person-to-person or animal-to-person contact. Routine screening of blood donations for West Nile Virus since 2003 has greatly reduced the risk of West Nile Virus infection through transfused blood.

What are the symptoms?
Most people infected with West Nile Virus have no symptoms at all. About 20 percent develop symptoms that include fever, fatigue, headache, and muscle or joint pains. These symptoms can last a few days to several weeks. Less than 1% of infected people will develop a more serious illness with symptoms that include headache, high fever, stiff neck, disorientation, convulsions, tremors and muscle weakness. Severe cases of the virus may lead to paralysis, coma or death.

Symptoms normally appear 3 to 15 days after the mosquito bite. People age 50 and older are more likely to develop severe symptoms from West Nile Virus.

How is it treated?
There is no specific treatment for West Nile Virus infection. In more serious cases, treatment may involve hospitalization where patients can receive intravenous fluids, respiratory support, prevention of secondary infections and nursing care.

What can be done to prevent infection?
Because there is currently no vaccine to protect humans from West Nile Virus, the best defense against the disease is to control mosquito populations, monitor for the presence of the virus, and prevent mosquito bites.

Protect yourself and your family

Don't give mosquitoes a place to breed - Mosquitoes lay their eggs in slow-moving or standing water. A small puddle of water can breed thousands of mosquitoes each week. From April to October, when mosquitoes are most active, take steps to prevent mosquitoes from breeding:

  • Remove sources of standing water, such as old tires, empty containers, pots, plastic ground covers, and anything else that holds water.
  • Change water in bird baths, ponds, pet dishes, and animal troughs twice a week.
  • Repair leaking faucets and sprinklers.
  • Clean clogged gutters.
  • Cover trash containers so they don't accumulate water.
  • Properly maintain and treat your pool and pond. Be sure pool covers do not hold pockets of water. Ornamental, self-contained ponds may be treated with larvicide to reduce mosquitoes. Follow label instructions and make sure it is for home use.
  • Organize neighborhood cleanup activities to remove sources of standing water.
  • Report areas of standing water by calling Clark County Mosquito Control’s 24-hour reporting line at (360) 397-8430.

Prevent mosquito bites
To reduce the risk of West Nile Virus, take the following safety measures to prevent mosquito bites:

  • Use mosquito repellent when you are outdoors, especially at dawn, dusk and early evening, when mosquitoes are most active. The most effective repellents contain the active ingredients DEET, Picaridin, or oil of lemon eucalyptus. Permethrin is also an effective repellent, but should be applied to clothing only, not directly on the skin.
  • Follow directions when using repellents, especially when applying on children. Don't allow children to apply repellents themselves.  Visit the Centers for Disease Control for more information on mosquito repellents.
  • Install or repair screens on windows and doors so mosquitoes can't get inside.
  • If possible, stay indoors during peak mosquito hours. But if being outside is irresistible on a warm summer evening, wear loose-fitting protective clothing such as long-sleeved shirts, long pants, shoes and socks, and hats, especially when going into woods or wetland. If heat makes extra clothing uncomfortable, be sure to use repellent.
  • Place mosquito netting over infant carriers when outdoors.

Reporting dead birds
Reporting dead birds is important to monitoring West Nile virus and Avian Influenza diseases. West Nile virus has not been detected in Southwest Washington. CDC maintains a list of reported human cases of the disease. As a result of the continued spread of West Nile virus, Public Health and the Mosquito Control District have increased their efforts to monitor and prevent West Nile virus.

No Avian Influenza has been detected in birds anywhere in North America, though state biologists are monitoring for this. If you find a single dead waterfowl or shorebird, or five or more dead birds of another kind, please report it to Public Health. We will notify the Washington Department of Fish and Wildlife. They will evaluate whether or not the birds should be collected for testing.

  • Report a dead bird - Contact us or by calling Public Health at (360) 397-8482.

Only some crows, jays or raptors will be selected for West Nile Virus testing. If you have found a crow, jay or raptor and the bird is fresh and undamaged, please keep the bird for possible West Nile Virus testing. We will contact you within 24 hours to arrange testing. If you are not contacted within 24 hours, please dispose of the bird in your household garbage.

  • Handling dead birds
    • Do not handle dead birds with your bare hands. Use, gloves, a shovel or a plastic bag over your hand to pick up a dead bird.
    • Double-wrap the bird in two plastic bags and store it in a cool place, a refrigerator or freezer is ideal.
    • Do not bring dead birds to Public Health unless you have been directed to do so by Public Health staff.

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