West Nile Virus Prevention

West Nile Virus (WNV) is an illness carried by mosquitoes and passed on to people. It can make people ill with flu like symptoms and can even lead to death in some cases. Everyone needs to be aware of mosquitoes and keep them away.

Prevention: Practice the 7 Ds

  • DRAIN any standing water that may produce mosquitoes, including unmaintained swimming pools.
  • DAWN and DUSK are times to avoid being outdoors. These are the times when mosquitoes are most active.
  • DRESS appropriately by wearing long sleeves and pants when outside.
  • DEFEND yourself against mosquitoes by using an effective insect repellent such as DEET, Picaridin or Oil of Lemon Eucalyptus. Follow label directions.
  • DOOR and window screens should be in good working condition to prevent mosquitoes from entering your home.
  • DISTRICT personnel are available to address any mosquito problems you may be experiencing by calling (530) 342-7350.

What can you do if you see a mosquito problem or stagnant water problem?

To report mosquito problems or standing water, call: Butte County Mosquito & Vector Control District at (530) 342-7350 or (530) 533-6038. Learn more at www.bcmvcd.com. Also, ask about availability of free mosquito-eating fish for ornamental pools, ponds or stagnant swimming pools that cannot be immediately cleaned.

What can you do if you find a dead bird?

The California Department of Health asks the public to help in detecting the spread of WNV by reporting dead birds online at www.westnile.ca.gov. Those without Internet access can call 1-877-WNV-BIRD (1-877-968-2473). Reporting also helps the state determine where more mosquito control is needed, as mosquitoes acquire the virus from birds. Report birds that have been dead less than 48 hours. If someone does not get back to you within 24 hours, dispose of the dead bird, but do not handle dead birds with bare hands. Although there is no evidence that West Nile virus can be acquired by handling dead birds, it is best to use a shovel to put the bird in a plastic bag, put the bag in the trash and wash your hands.

How is WNV transmitted?

West Nile Virus is transmitted to humans and animals through a mosquito bite. Mosquitoes become infected when they bite and feed on infected birds. WNV is not transmitted by person-to-person contact. The California Department of Health Systems said there's evidence that WNV can be acquired via a blood transfusion or organ transplant from an infected donor, and from breastfeeding or during pregnancy from mother to baby, although it said this is unlikely.

What can happen if you become infected with WNV?

No symptoms for most people. Most individuals (about 80 percent) who are infected with WNV will not experience any illness.

Mild symptoms for some people. Others (about 20 percent), will have only mild symptoms, such as fever, headache, body aches, nausea and vomiting and sometimes swollen lymph glands or a skin rash on the chest, stomach or back, according to the California Department of Health Systems (CDHS). Symptoms can last a few days, though even healthy people have been sick for several weeks.

Serious symptoms for few people. WNV can be severe in the elderly and individuals with weakened immune systems. About 1 in 150 people develop serious symptoms, according to the CDHS. Severe symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis; these symptoms may last several weeks, and neurological effects may be permanent.

In California in 2015 there were a total of 783 WNV cases in humans, with 53 deaths, according to the CDHS. In Butte County, 25 people were reported to have WNV in 2005, up from seven the year prior.

How soon do infected people get sick?

If people develop symptoms, it typically happens between three and 14 days after they are bitten by the infected mosquito, according to westnile.ca.gov.

How is WNV infection treated?

There is no specific treatment for WNV infection. In cases with milder symptoms, the symptoms pass on their own. In more severe cases, people usually need to go to the hospital where they can receive supportive treatment including intravenous fluids, help with breathing and nursing care, according to the CDHS.

Is there a vaccination against WNV?

There is no vaccine to prevent WNV in humans. However, there is a vaccine for horses.


For recorded information on West Nile Virus, call the Enloe West Nile Virus Hotline at (530) 332-7017, or refer to these additional resources:

Local Mosquito & Vector Control District Offices:

  • Butte County Mosquito & Vector Control: (530) 533-6038 or www.bcmvcd.com
  • Durham Mosquito Abatement District: (530) 345-2875
  • Oroville Mosquito Abatement District: (530) 534-8383

Horse owners:

Call your local veterinarian or try this site for further reading and resources: westnile.ca.gov/veterinarian


  • video-img

    Drs. Voelker and Lobosky honored with 2014 Physician Legacy Award

  • video-img

    Drs. Voelker and Lobosky honored with 2014 Physician Legacy Award

  • video-img

    Drs. Voelker and Lobosky honored with 2014 Physician Legacy Award

  • video-img

    Drs. Voelker and Lobosky honored with 2014 Physician Legacy Award

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