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Topics > Healthy Outlook > Various Mosquito Repellents Can Help Combat West Nile Virus

Various Mosquito Repellents Can Help Combat West Nile Virus

Published by Contra Costa Times
Posted on Fri, Sep. 08, 2006

By Francie Wise, RN, MPH

WEST NILE VIRUS (WNV) recently claimed the life of an elderly Contra Costa woman, making hers the first confirmed death from the mosquito-borne virus in our county.

Two other human WNV cases in involving Contra Costa residents also have been reported. Fortunately, these people are recovering.

All three cases involve people living in Central Contra Costa County, but we can't be sure about where they were bitten by an infected mosquito, so we have to assume that everyone in the county and the state are at risk for WNV.

There is no vaccine for WNV but we can protect ourselves and our loved ones, especially by wearing insect repellent.

Though the most effective repellents are those made with DEET, the chemical shouldn't be used on infants or pets and some people just can't stand the feel or smell of it.

Other effective repellents include picaradin and oil of lemon eucalyptus, a plant-based repellent. In two recent scientific publications, when oil of lemon eucalyptus was tested against mosquitoes, it provided protection similar to repellents with low concentrations of DEET.

The New England Journal of Medicine published a laboratory study on the effectiveness of different repellents. Some of the results are surprising.

The Centers for Disease Control and Prevention recommends using products that have been shown to work in scientific trials and that contain active ingredients registered with the U.S. Environmental Protection Agency (EPA). Use repellents as directed.

In addition to repellent, use the following tips to help prevent the spread of WNV:

  • Limit the amount of time spent outdoors at dawn and dusk, or at other times when mosquitoes are active particularly during mosquito season from May to October.
  • Wear long-sleeved shirts and long pants when outdoors.
  • Fix holes in screens and make sure they are tightly attached to the doors and windows.
  • Eliminate standing water from collecting on your property. Mosquitoes can breed in any puddle or standing water that lasts for more than four days.
  • If you can't avoid standing water and can't use chlorine, use a commercial mosquito preventer sold in many hardware stores. It comes as granules or in the shape of small doughnuts.
  • Report dead birds, which can carry WNV, online at, or by calling 877-WNV-BIRD (877-968-2473).

For information concerning West Nile virus, call the Contra Costa Health Services Department at 888-959-9911 or visit the Web site at

Wise is director of Communicable Disease Programs and public health nursing for Contra Costa Health Services.

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