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West Nile Virus Alert Levels

West Nile Virus Activity in Clark County

Current Alert Level:

WNv Alert Level Definitions

Alert level

Description

No risk of human outbreak

Off season. No significant mosquito activity.

Remote risk of human outbreak

No West Nile virus activity (no birds, mosquitoes, horses, or people have tested positive for West Nile virus) in the state, Clark County, or bordering counties. Conditions are not conducive for mosquitoes to breed.

Low risk of human outbreak

Environmental conditions are ideal for mosquitoes and West Nile virus is detected in mosquitoes and dead birds in Clark County.

High risk of human outbreak

Environmental conditions are ideal for mosquitoes and West Nile virus is detected in mosquitoes and dead birds in Clark County. One or more equine (horse) cases has been identified and/or one or more human cases have been diagnosed in Clark County.

Human outbreak in progress

Multiple confirmed human cases with conditions favoring continued transmission to people, including persistent high infection rates in mosquitoes.

Frequently Asked Questions

  • How do I report dead birds?

    Washington state’s Online Dead Bird Reporting System for West Nile Virus (WNV) surveillance has been discontinued. Research has shown that testing local mosquito populations is the best way to detect the presence of WNV. The Clark County Mosquito Control District will continue to actively monitor and test local mosquito populations.

    We wish to thank community members who have diligently reported dead birds over the past years. Your partnership and dedication are much appreciated.

    Other state agencies monitor dead birds for avian influenza throughout the year. For questions or reporting, please contact:

  • How is West Nile virus spread?

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

  • How is West Nile virus 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 are the symptoms of West Nile virus?

    Most people infected with West Nile virus have no symptoms. 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 percent 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 typically appear three to 15 days after the mosquito bite. People age 50 and older are more likely to develop severe symptoms from West Nile virus.

  • What can be done to prevent West Nile virus infection?

    Currently there is 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.

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