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West Nile Virus Activity 2022

Updates about West Nile virus in the San Gabriel Valley

This page updated 11/1/22

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.

May contain: animal, bird, and crow

2022 West Nile Virus Activity

West Nile Virus Positive Mosquito Samples

A sample is a random collection of 10-50 mosquitoes from a trap. Positive mosquito samples from routine and randomized trapping provide insight into of the spread of West Nile virus.

City/CommunityNumber of WNV+ Mosquito SamplesDate of first report
Alhambra118/1
Altadena (LA County)2 9/12
Arcadia147/1
Azusa29/12
Baldwin Park88/15
Bradbury38/26
Claremont28/26
Covina78/22
Duarte58/15
East San Gabriel (LA County)97/11
El Monte117/1
Industry29/19
Irwindale27/11
La Puente48/8
Monrovia78/15
Monterey Park68/1
Pasadena146/20
Pomona58/26
Rosemead78/26
San Dimas110/24
San Gabriel47/1
Sierra Madre38/1
South Monrovia Island (LA County)28/8
South Pasadena117/1
Temple City68/1
Walnut58/15
West Covina68/22
West Valinda/Bassett (LA County)147/25
TOTAL165--

West Nile Virus Positive Dead Birds

People report dead birds they observe in their community. Positive dead birds are an indication West Nile virus is widespread in the region.

City/CommunityNumber of WNV+ dead birdsDate of first report
Alhambra39/6
Claremont29/19
Monrovia18/26
Pomona19/6
South Pasadena18/1
Temple City19/19
West Covina29/12
TOTAL11--

Wonder how your community compares to the rest of Southern California?

Click HERE for an interactive map. Explore your neighborhood!