September 25, 2018 – West Nile Virus (WNV) is a disease that is transmitted by the bites from infected mosquitoes. WNV first appeared in California in 2003 and infections occur most often in the summer and early fall when mosquitoes are active. As of September 21, 2018, the California Department of Public Health (CDPH) had received reports of 100 human cases this season which is lower than the 174 cases reported at this point last year; however, WNV activity is fairly widespread in California and the state has seen a recent rise in human cases. Even as we move into fall, residents should continue to take precautions against mosquito bites.

For most people, the risk of serious illness is low; however, some people (less than one percent) can develop a serious neurologic illness such as meningitis or encephalitis (brain inflammation). People 50 years of age or older have the greatest risk of complications.

To reduce the risk of being infected, residents are encouraged to:

  • Remain indoors at dawn and dusk when mosquitos are most active, or
  • Wear long sleeves and pants during dusk and dawn.
  • Defend yourself by using an effective insect repellent and following the label directions.
  • Remove water standing for more than 3 days from bird baths, pet dishes, flower pots, outdoor stored automotive tires or neglected swimming pools.
  • Keep door and window screens in good working condition.

California’s WNV website ( includes the latest information on WNV activity in the state. Californians are encouraged to report all dead birds through the website. Dead birds can also be reported by calling toll-free 1-877-WNV-BIRD (968-2473).