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West Nile virus activity in San Gabriel Valley

Updates about West Nile virus in the San Gabriel Valley
Last Updated on 09/25/2023 9 AM

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

The San Gabriel Valley Mosquito & Vector Control District has been tracking West Nile virus activity in mosquito populations since 2003. Dead bird data is stored with the California Department of Public Health. You can access the dead bird data HERE.

West Nile virus Facts

  1. West Nile virus is the most common mosquito-borne disease that affects 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 collect samples of mosquitoes. The mosquito samples are tested for mosquito-borne diseases, such as West Nile virus. In addition, dead birds, which can carry West Nile virus, are submitted for testing.

Year-to-Date Statistics for 2023

2023 WNV+ 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 the spread of West Nile virus.

City/CommunityDate of First DetectionPositives
 Arcadia09/13/23 1
Azusa 07/06/23 5
Baldwin Park08/02/232
Bradbury 08/01/233
Charter Oak06/22/236
Duarte  08/15/23 1
East San Gabriel08/01/23
 Irwindale08/08/23 3
La Puente08/30/23 6
La Verne08/01/2312
Monterey Park09/06/231
Rosemead 08/15/232
San Dimas 08/01/239
San Gabriel  09/12/23 5
Sierra Madre 07/11/232
South Pasadena07/25/231
Temple City07/18/232
West Covina07/20/2326
 Total # of Positive Mosquito Samples this Year197

 2023 WNV+ 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/CommunityDate of First DetectionPositives
Covina 06/02/2310
Pomona 9/21/231
San Dimas08/31/231
Temple City  08/15/231
Total # of Positive Dead Birds This Year14

Take a look at mosquito disease activity throughout California using the VectorSurv Map!

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