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West Nile Virus Activity 2020

May contain: animal, bird, and crow

West Nile virus Facts

  1. West Nile virus is the most common mosquito-borne disease that affect residents in Los Angeles County
  2. Public health agencies detect West Nile virus every year in L.A. County. This means the virus is found naturally in our city environments, which means it's endemic.
  3. Our agency uses routine traps to colect samples of mosquitoes. The mosquito samples are tested for a mosquito-borne diseases, such as West Nile virus. In addition, dead birds, which can carry West Nile virus, are submitted for testing.

Our agency reports data related to mosquitoes. Human cases are reported by the L.A. County Department of Public Health and Pasadena Health Department.


2020 West Nile Virus Activity

 Last update: 11/6/20

West Nile Virus Positive Mosquito Samples

A sample is a random collection of 10-50 mosquitoes from a trap

City/CommunityNumber of WNV+ Mosquito SamplesDate of first posting
Baldwin Park29/17
Bassett (Unincorporated L.A. County)78/24
El Monte28/24
La Puente19/4
Monterey Park39/24
Pomona3 8/5
San Gabriel38/28
Temple City110/16
Unincorporated L.A. County area around Fairgrove Nursery110/1
West Covina48/28
West Puente Valley (Unincorporated L.A. County)28/10


West Nile Virus Positive Dead Birds

People report dead birds they observe in their community.

City/CommunityNumber of WNV+ dead birdsDate of first report
La Verne18/17
Monterey Park111/6
West Covina110/12