West Nile Virus

When dealing with West Nile virus, prevention is your best bet. Avoiding mosquito bites reduces your risk of getting this disease, along with others that mosquitoes can carry. Take the commonsense steps below to reduce your risk:

  • avoid mosquito bites and use insect repellent;
  • clean out standing water from the places where you work and play;
  • Follow the four "D's" listed below;
  • work with your local mosquito control to stop mosquito development.


1. Defending Yourself Against Mosquitoes - The 4 D's

Drain standing water around the house weekly since it's where mosquitoes lay eggs, including: tires, cans, flowerpots, clogged rain gutters, rain barrels, toys, puddles and even unused fountains.

Dusk & Dawn
Dusk and dawn are when mosquitoes that carry the virus are most active, so limit outdoor activities or take precautions to prevent mosquito bites.

Deet is an effective ingredient to look for in insect repellents.  Always follow label instructions carefully.

Dress in long sleeves and pants during dawn and dusk or in areas where mosquitoes are active.

2. Avoid Mosquito Bites

Apply Insect Repellent Containing DEET (Look for: N,N-diethyl-meta-toluamide )
Apply to exposed skin when you go outdoors. Even a short time being outdoors can be long enough to get a mosquito bite. For details on when and how to apply repellent, see Mosquito Repellent.

Clothing Can Help Reduce Mosquito Bites
When possible, wear long-sleeves, long pants and socks when outdoors. Mosquitoes may bite through thin double layers of clothing are even better.

Get double protection: wear long sleeves during peak mosquito biting hours, and spray DEET repellent directly onto your clothes.

Be Aware of Peak Mosquito Hours
The hours from dusk to dawn are peak mosquito biting times for many species of mosquitoes. Take extra care to use repellent and protective clothing during evening and early morning hours. Consider avoiding outdoor activities during these times.

2. Mosquito-Proof Your Home

Drain Standing Water (View Home)
Mosquitoes lay their eggs in standing water. Limit the number of places around your home for mosquitoes to develop by getting rid of items that hold water.

Install or Repair Screens
Some mosquitoes like to come indoors. Keep them outside by having well-fitting screens on both windows and doors. Offer to help neighbors whose screens might be in bad shape.  

3. Help Your Community

Report Dead Birds to Local Authorities
Dead birds may be a sign that West Nile virus is circulating between birds and the mosquitoes in an area. Over 225 species of birds are known to have been infected with West Nile virus, though not all infected birds will die. It's important to remember that birds die from many other causes besides West Nile virus.

By reporting dead birds to toll free hotline 1-877-968-2473. You can play an important role in monitoring West Nile virus. Check the Identify and Report Dead Birds page to find information about reporting dead birds in your area.

Mosquito Control Programs
To find your local mosquito control agency click here. The Mosquito and Vector Control Association of California (MVCAC) holds a wealth of knowledge on control and surveillance in California. More questions about mosquito control? A source for information about pesticides and repellents is the National Pesticide Information Center, which also operates a toll-free information line: 1-800-858-7378 (check their Web site for hours).

Clean Up
Mosquito breeding sites can be anywhere. Neighborhood clean up days can be organized by civic or youth organizations to pick up containers from vacant lots and parks, and to encourage people to keep their yards free of standing water. Mosquitoes don't care about fences, so it's important to control breeding sites throughout the neighborhood.

More Info


West Nile Virus and
Dead Bird Hotline

(877) 968-BIRD (2473)

or online at westnile.ca.gov