Human Cases
Year-to-date: 252 Counties: 23
There were 42 new WNV positive human cases reported in California this week from the following counties: Fresno (1), Kern (6), Los Angeles (25), Orange (4), San Diego (2), San Luis Obispo (1), Stanislaus (1), Sutter (1), and Yolo (1).
19 WNV-related fatalities have been reported to CDPH this year from 8 jurisdictions: Butte (3), Glenn (2), Kings (1), Los Angeles (4), Orange (4), Sacramento (2), Tuolumne (1), and Yolo (2).
252 human cases from 23 counties have tested positive for WNV in 2026.
Dead Birds
Year-to-date: 702 Counties: 25
There were 45 new WNV positive dead birds reported in California this week from the following counties: Butte (1), Contra Costa (2), Los Angeles (6), Orange (22), Riverside (2), Sacramento (1), San Diego (6), and Santa Clara (5). This is the first WNV positive dead bird from Butte County this year.
702 dead birds from 25 counties have tested positive for WNV in 2026.
Mosquito Samples
Year-to-date: 3839 Counties: 29
There were 109 new WNV positive mosquito samples reported in California this week from the following counties: Fresno (4), Kern (4), Los Angeles (38), Madera (8), Merced (1), Orange (16), Riverside (7), Sacramento (4), San Bernardino (4), San Diego (4), San Joaquin (12), Stanislaus (2), Tulare (3), and Yolo (2).
3,839 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: 149 Counties: 11
There were 6 new WNV positive sentinel chickens reported in California this week from the following counties: Calaveras (2), Contra Costa (1), Los Angeles (1), and Tehama (2). This is the first indication of WNV from Calaveras County this year.
149 sentinel chickens from 11 counties have tested positive for WNV in 2026.
Horses
Year-to-date: 14 Counties: 13
14 horses from 13 counties have tested positive for WNV in 2026.