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West Nile Virus

West Nile virus is a disease caused by the bites of infected mosquitoes and spreads during warm weather months when mosquitoes are most active. The mosquitoes that can carry West Nile virus are found throughout Los Angeles County. In Los Angeles County, mosquito season peaks May through November.

Everyone is at risk of West Nile virus infection, but people at most risk of serious illness are people over 50 and those with existing medical conditions. West Nile virus can also infect animals like birds and horses.

It is important that LA County residents take actions to protect themselves from West Nile virus.

How to Prevent West Nile Infection

Avoid getting mosquito bites

  • Use bug spray that is Environmental Protection Agency (EPA) approved and contains DEET, Picaridin or IR3535 as ingredients
  • Wear long-sleeved shirts and long pants or clothing specially treated to avoid mosquito bites.
  • Stay indoors when possible during evening to early morning hours (dusk to dawn) when the mosquitoes that spread West Nile virus are most active.

Get rid of places where mosquitoes lay eggs

  • Dump and drain water from potted plants, pet water bowls, bird baths, and other places where water collects.
  • Mosquitoes can breed in very small amounts of water, even bottle caps. Check for and remove all items where water collects.
  • Mosquitoes lay their eggs in standing water and can complete the cycle from egg to adult in just 5 days.

Keep mosquitoes out of your home

  • Make sure any open windows or doors have screens to keep mosquitos out.
  • Repair or replace screens that have tears or holes.

Public Health is Working for You

Due to the rising concern about West Nile virus, Public Health has been quick to respond by:

  • Investigating possible cases of West Nile virus infection in our communities.
  • Updating our website and sharing information and education on West Nile virus with residents.
  • Reaching out to medical providers to increase awareness of West Nile virus infection.
  • Working closely with vector control agencies.

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Public Health has made reasonable efforts to provide accurate translation. However, no computerized translation is perfect and is not intended to replace traditional translation methods. If questions arise concerning the accuracy of the information, please refer to the English edition of the website, which is the official version.
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