The disease surveillance program serves as an early warning system in the detection of mosquito-borne viruses that can infect people and animals.

The District uses the following factors to assess health risk in your community:

  • Higher-than-average daily temperatures
  • Mosquito Population Monitoring – Using traps set up in every community
  • Mosquito Testing for Diseases
  • Dead Birds – A CA state program: Dead birds help determine spread of West Nile virus
  • Sentinel Chickens – Chickens develop antibodies to West Nile virus, which can be detected by testing.

Using these measurements, the District is able to protect your health by responding appropriately to mosquito-borne disease threats.


Yearly Summary (2008-2019)

Note: Human cases reported by Los Angeles County Department of Public Health


Year-to-Date Statistics for 2020

City/Community Date First Detected #WNV Positive Mosquito Sample to Date this Year
Bell Gardens 7/14/2020 1
Bellflower 7/14/2020 2
Burbank 7/14/2020 3
Canoga Park 7/22/2020 2
Commerce 7/30/2020 1
Downey 7/14/2020 3
East Los Angeles 7/30/2020 1
Encino 7/15/2020 4
Hacienda Heights 5/20/2020 2
La Cañada Flintridge 7/28/2020 1
La Mirada 7/15/2020 1
Los Feliz 7/29/2020 1
Lakewood 7/23/2020 1
Montebello 7/29/2020 2
Northridge 7/21/2020 2
North Hills 7/15/2020 2
North Hollywood 6/18/2020 6
Panorama City 7/15/2020 3
Pico Rivera 5/20/2020 6
Porter Ranch 7/21/2020 2
Rowland Heights 7/10/2020 1
Santa Fe Springs 7/15/2020 3
Sherman Oaks 6/11/2020 4
Signal Hill 7/09/2020 1
South Gate 7/28/2020 1
South Park 7/30/2020 1
Studio City 6/18/2020 5
Sunland 7/24/2020 1
Tarzana 7/21/2020 2
Toluca Lake 6/18/2020 4
Valley Glen 6/18/2020 3
Valley Village 6/18/2020 6
Van Nuys 7/02/2020 4
Whittier 7/15/2020 1
Winnetka 7/07/2020 2
Woodland Hills 6/17/2020 1
Total #WNV Positive Mosquito Sample to Date this Year 86

Year-to-Date Statistics for 2020

WNV+ = Number of West Nile virus positive samples confirmed