Human Cases
Year-to-date: 46 Counties: 14
There were 17 new WNV positive human cases reported in California this week from the following counties: Butte (3), Fresno (3), Glenn (1), Kings (1), Los Angeles (4), Orange (2), Sacramento (1), Tulare (1), and Yuba (1). This is the first WNV positive human case from Yuba County this year.
4 WNV-related fatalities have been reported to CDPH this year from 4 jurisdictions: Butte (1), Fresno (1), Glenn (1), and Kings (1).
46 human cases from 14 counties have tested positive for WNV in 2026.
Dead Birds
Year-to-date: 437 Counties: 22
There were 64 new WNV positive dead birds reported in California this week from the following counties: Alameda (1), Contra Costa (1), Los Angeles (14), Merced (1), Orange (18), Placer (2), Riverside (1), Sacramento (7), San Bernardino (2), San Diego (3), Santa Clara (8), Sonoma (1), Ventura (3), Yolo (1), and Yuba (1). This is the first indication of WNV from Sonoma County this year.
437 dead birds from 22 counties have tested positive for WNV in 2026.
Mosquito Samples
Year-to-date: 2644 Counties: 29
There were 409 new WNV positive mosquito samples reported in California this week from the following counties: Alameda (2), Fresno (14), Kern (11), Kings (1), Los Angeles (66), Madera (44), Merced (6), Orange (90), Placer (20), Riverside (14), Sacramento (14), San Bernardino (9), San Diego (12), San Joaquin (21), Shasta (1), Solano (2), Stanislaus (28), Sutter (3), Tulare (46), Yolo (4), and Yuba (1). This is the first WNV positive mosquito sample from Solano County this year.
2,644 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: 64 Counties: 7
There were 11 new WNV positive sentinel chickens reported in California this week from the following counties: Colusa (3), Shasta (2), Sutter (1), and Tulare (5). This is the first WNV positive sentinel chicken from Shasta County this year.
64 sentinel chickens from 7 counties have tested positive for WNV in 2026.
Horses
Year-to-date: 6 Counties: 6
There was 1 new WNV positive horse reported in California this week from Fresno County. This is the first WNV positive horse from Fresno County this year.
6 horses from 6 counties have tested positive for WNV in 2026.