Human Cases
Year-to-date: 147 Counties: 21
There were 25 new WNV positive human cases reported in California this week from the following counties: Butte (2), Fresno (4), Glenn (1), Kern (3), Kings (3), Los Angeles (2), Orange (3), Sacramento (1), San Bernardino (1), Stanislaus (3), Sutter (1), and Yolo (1).
10 WNV-related fatalities have been reported to CDPH this year from 5 jurisdictions: Butte (3), Glenn (2), Kings (1), Sacramento (2), and Yolo (2).
147 human cases from 21 counties have tested positive for WNV in 2026.
Dead Birds
Year-to-date: 623 Counties: 24
There were 48 new WNV positive dead birds reported in California this week from the following counties: Contra Costa (1), Los Angeles (22), Orange (10), Placer (1), Riverside (2), Sacramento (2), San Bernardino (2), San Diego (3), Santa Clara (2), Stanislaus (1), and Yolo (2). This is the first WNV positive dead bird from Stanislaus County this year.
623 dead birds from 24 counties have tested positive for WNV in 2026.
Mosquito Samples
Year-to-date: 3544 Counties: 29
There were 120 new WNV positive mosquito samples reported in California this week from the following counties: Kern (5), Los Angeles (38), Madera (4), Merced (1), Orange (19), Placer (2), Riverside (5), Sacramento (4), San Bernardino (6), San Diego (2), San Joaquin (12), Santa Clara (2), Shasta (1), Stanislaus (3), Tulare (15), and Yolo (1).
3,544 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: 141 Counties: 10
There were 3 new WNV positive sentinel chickens reported in California this week from the following counties: Colusa (1), Los Angeles (1), and Shasta (1).
141 sentinel chickens from 10 counties have tested positive for WNV in 2026.
Horses
Year-to-date: 14 Counties: 13
There were 3 new WNV positive horses reported in California this week from the following counties: Amador (1), El Dorado (1), and Shasta (1). These are the first WNV positive horses from El Dorado and Shasta counties this year.
14 horses from 13 counties have tested positive for WNV in 2026.