First-ever Sign of West Nile Virus Activity in Spokane County

This afternoon the Spokane Regional Health District was notified by the Washington State Department of Health (DOH), that a dead magpie sent to DOH's lab for testing on September 2, 2009, was positive for West Nile Virus (WNV). The bird was reported by a citizen in the West Plains area, and is the first animal that has tested positive for WNV in Spokane County.

"The good news is that we are almost at the end of mosquito season," said Dr. Joel McCullough, Health Officer for the Spokane Regional Health District. "However it is still important now for people to protect themselves from mosquito bites, to reduce their chance of getting West Nile disease."

Most people who are bitten by an infected mosquito develop no symptoms or mild symptoms, but West Nile infection can cause encephalitis (inflammation of the brain) or meningitis (inflammation of the lining of the spinal cord and brain). People over age 50 have the highest risk for serious illness.

With mosquitoes shown to carry West Nile Virus present in many areas in our region, the Spokane Regional Health District has been urging people to reduce their chances of being bitten.

To avoid mosquito bites:

  • Wear long sleeved shirts and long pants
  • Staying indoors around dawn and dusk when mosquitoes are most active
  • Make sure that door and window screens are in good working condition
  • Use a mosquito repellent when outdoors in areas where mosquitoes are active – always follow label instructions when using mosquito repellents
  • Reduce mosquito breeding sites around your home. Turn over old buckets or cans, empty water from old tires and frequently change water in birdbaths, pet dishes and water troughs to eliminate the small puddles of water in which many mosquito species develop.

West Nile virus is primarily a bird and mosquito disease. Mosquitoes become infected by feeding on infected birds, and then pass the virus to uninfected birds.  Humans, horses or other animals can become infected by mosquitoes but cannot pass on the infection to back to mosquitoes. Crows, ravens, magpies and jays are especially susceptible to dying from the virus.

Mosquito Repellents:
Repellents are available in various forms and concentrations; they can be applied directly to the skin, to clothing, or found in pre-treated clothing.

  • DEET (chemical name, N,N-diethyl-meta-toluamide or N,N-diethly-3-methyl-benzamide) is the active ingredient found in many insect repellent products. It is used to repel biting pests such as mosquitoes and ticks. Products containing DEET currently are available in a variety of liquids, lotions, sprays. Formulations registered for direct application to human skin contain from 4 to 100 percent DEET, although percentages higher than 50% do not increase the length of protection. DEET formulations as high as 50% are recommended for both adults and children over 2 months of age. Protect infants less than 2 months of age by using a carrier draped with mosquito netting with an elastic edge for a tight fit.
  • Picaridin is a colorless, nearly odorless liquid active ingredient that is used as an insect repellant against biting flies, mosquitoes, chiggers, and ticks. Products contain a range of 5 to 20 percent of the active ingredient. Picaridin-containing repellent needs to be applied more frequently than DEET.
  • Oil of Lemon Eucalyptus Is an extract from the leaves and twigs of Eucalyptus cittriodora that repels mosquitoes and deer ticks. Products contain a range of 30 to 40 active ingredient. Labels on products containing oil of lemon eucalyptus specify that they should not to be used on children under the age of three years.
  • IR3535 is used as an insect repellent against mosquitoes, deer ticks, and biting flies.

Area Repellents and Repellents Used on Clothing

  • Permethrin Permethrin products  are used on clothing, shoes, bed nets, and camping gear. Permethrin-impregnated clothing such as pre-treated shoes, socks, and pants repel and kill ticks, mosquitoes, and other insects and retain this effect after repeated laundering. Permethrin is also found in treated tents, tarps, bed nets, sleeping bags, and mattresses.

Length of protection from mosquito bites offered by any product varies with the amount of active ingredient, ambient temperature, amount of physical activity/perspiration, water exposure, and other factors. For long duration protection use a long lasting formula and re-apply as necessary, according to label instructions.  

EPA recommends the following precautions when using insect repellents:

  • Apply repellents only to exposed skin and/or clothing (as directed on the product label.) Do not use repellents under clothing.
  • Never use repellents over cuts, wounds or irritated skin.
  • Do not apply to eyes or mouth, and apply sparingly around ears. When using sprays, do not spray directly on face-spray on hands first and then apply to face.
  • Do not allow children to handle the product. When using on children, apply to your own hands first and then put it on the child. You may not want to apply to children's hands.
  • Use just enough repellent to cover exposed skin and/or clothing. Heavy application and saturation are generally unnecessary for effectiveness. If biting insects do not respond to a thin film of repellent, then apply a bit more.
  • After returning indoors, wash treated skin with soap and water or bathe. This is particularly important when repellents are used repeatedly in a day or on consecutive days. Also, wash treated clothing before wearing it again. (This precaution may vary with different repellents-check the product label.)
  • If you or your child get a rash or other bad reaction from an insect repellent, stop using the repellent, wash the repellent off with mild soap and water, and call a local poison control center for further guidance. If you go to a doctor because of the repellent, take the repellent with you to show the doctor.

Other than those listed above, EPA does not recommend any additional precautions for using registered repellents on pregnant or lactating women, or on children.

For additional information, call 324-1560 ext. 7.