skip navigation , health centers and clinics , search , accessibility statement , Página en español ,
Contra Costa Health Services
contact us

Topics > Healthy Outlook > Find out about West Nile Virus

Find out about West Nile Virus

Published by Contra Costa Times
Posted on Fri, Aug. 18, 2006

By Francie Wise, RN, MPH

MOSQUITOES AND birds infected with the West Nile virus have been found in Contra Costa County. Our residents must take precautions against the disease right now.

Although no human cases of West Nile virus have been reported in our county so far this year, there have been six confirmed human cases in other counties in California.

Most people infected with the virus don't get sick, but in rare cases the disease can be fatal. Even if you survive a severe illness with West Nile virus, you may take months to recover and suffer permanent nervous system damage.

Protect yourself and your family, especially during the mosquito season, which usually lasts from May through October. We have compiled a list of frequently asked questions about West Nile virus:

  • What is West Nile virus?

    It is a virus spread by mosquitoes that can cause infection and illness in people. Last year, Contra Costa County had 11 human West Nile virus cases but no deaths. In 2005, California reported 935 human West Nile virus infections, including 19 deaths.

  • How do people get West Nile virus?

    By the bite of an infected mosquito. Mosquitoes get the virus by feeding on the blood of an infected bird or horse. Not all mosquitoes transmit West Nile virus. It has not been transmitted from person to person.

  • What animals can get West Nile virus?

    Most often birds, and less commonly horses. West Nile virus does not usually make dogs and cats sick. There is no evidence of people getting the virus directly from animals.

  • What are the symptoms of West Nile virus?

    Usually none. Most people infected by West Nile virus don't even know they have it. Those who get sick may experience fever, headache, body aches, skin rash and swollen lymph glands. More severe cases cause high fever, neck stiffness, disorientation, coma, convulsions, muscle weakness, paralysis, brain swelling and, rarely, death.

  • How long after the mosquito bite do West Nile virus symptoms start?

    Usually two to 15 days.

  • Who is at risk of getting West Nile virus?

    Everyone. People older than 50 and infants have the highest risk of getting severely ill.

  • How is West Nile virus treated?

    There is no human vaccine or specific treatment to prevent or cure West Nile virus. A person may be treated to reduce symptoms. In severe cases, hospitalization may be required.

  • What can be done to protect against West Nile virus?

    Use insect repellent containing DEET, picaradin or oil of lemon eucalyptus, according to manufacturer's labels. These repellents are only for humans -- do not use on animals.

    Minimize time spent outdoors at dawn and dusk. Wear long-sleeved shirts and long pants when outdoors.

    Fix holes in windows and door screens.

Help prevent West Nile virus by reducing mosquito populations. Don't let puddles or water stand for more than four days. Empty (and refill) ceramic pots and birdbaths every four days.

Aerate ornamental ponds or stock them with fish that eat mosquito eggs. Or, use a mosquito preventer, which is sold as small doughnuts or granules in many hardware stores.

In Contra Costa, free mosquito fish are available through Contra Costa Mosquito & Vector Control (925-685-9301.) Vector control also sprays in specific problem areas to help prevent mosquito breeding.

Report dead birds, which can carry West Nile virus, by submitting a report online at or calling 877-WNV-BIRD (968-2473).

For more information about West Nile virus, visit Contra Costa Health Services Web site.

Francie Wise is director of communicable disease programs and public health nursing for Contra Costa Health Services.

Contra Costa County home page