Human Cases
Year-to-date: 65 Counties: 16
There were 19 new WNV positive human cases reported in California this week from the following counties: Butte (2), Glenn (1), Kings (1), Los Angeles (6), Orange (1), Riverside (1), Sacramento (5), Tuolumne (1), and Yolo (1). This is the first WNV positive human case from Riverside County this year.
This is the first indication of WNV from Tuolumne County this year.
5 WNV-related fatalities have been reported to CDPH this year from 4 jurisdictions: Butte (2), Glenn (1), Kings (1), and Sacramento (1).
65 human cases from 16 counties have tested positive for WNV in 2026.
Dead Birds
Year-to-date: 481 Counties: 23
There were 44 new WNV positive dead birds reported in California this week from the following counties: Alameda (1), El Dorado (1), Los Angeles (10), Orange (16), Placer (1), Riverside (1), Sacramento (2), San Bernardino (1), San Diego (3), Santa Clara (3), and Yolo (5). This is the first indication of WNV from El Dorado County this year.
481 dead birds from 23 counties have tested positive for WNV in 2026.
Mosquito Samples
Year-to-date: 3001 Counties: 29
There were 357 new WNV positive mosquito samples reported in California this week from the following counties: Alameda (2), Butte (2), Fresno (9), Imperial (1), Kern (11), Lake (1), Los Angeles (72), Madera (21), Merced (23), Orange (107), Placer (8), Riverside (1), Sacramento (4), San Bernardino (6), San Joaquin (22), Shasta (5), Solano (4), Stanislaus (23), Sutter (1), Tulare (27), and Yolo (7).
3,001 mosquito samples from 29 counties have tested positive for WNV in 2026.
A mosquito sample may contain up to 50 individual mosquitoes.
Sentinel Chickens
Year-to-date: 106 Counties: 9
There were 42 new WNV positive sentinel chickens reported in California this week from the following counties: Butte (8), Lake (1), Los Angeles (22), Sutter (7), and Tehama (4). This is the first WNV positive sentinel chicken from Lake County this year.
This is the first indication of WNV from Tehama County this year.
106 sentinel chickens from 9 counties have tested positive for WNV in 2026.
Horses
Year-to-date: 8 Counties: 8
There have been 2 new WNV positive horses reported in California this week from Contra Costa (1) and Stanislaus (1) counties. These are the first WNV positive horses from Contra Costa and Stanislaus counties this year.
8 horses from 8 counties have tested positive for WNV in 2026.