FAQs: Frequently Asked Questions

A person can reduce their risk of WNV infection by:

1. Staying indoors at dawn and dusk when mosquitoes are most active.
2. Using a repellent containing the active ingredients DEET, Picaridin, oil of lemon eucalyptus, or IR3535 before going outdoors.
3. Dumping or draining water that has been standing for more than three days, including neglected swimming pools, birdbaths, pet dishes, tire swings, and flower planters. These items provide a perfect place for mosquitos to lay their eggs, which increases the risk of being infected with WNV.
4. Repairing broken or torn screens on windows and doors to keep mosquitoes from entering your home.

Infected mosquitoes. Most often, WNV is spread by the bite of an infected mosquito. Mosquitoes are WNV carriers ("vectors") that become infected when they feed on infected birds. Infected mosquitoes can then spread WNV to humans and other animals when they bite.

West Nile virus (WNV) is a mosquito-borne disease that was originally found in Africa. In 1999, it was detected in the eastern United States; since then the virus has spread throughout the United States and is well established in most states, including California.