Human Cases
Year-to-date: 86 Counties: 21
There were 22 new WNV positive human cases reported in California this week from the following counties: Glenn (1), Los Angeles (6), Madera (1), Merced (1), Orange (2), Sacramento (2), San Bernardino (1), San Joaquin (1), Stanislaus (5), and Sutter (2). These are the first WNV positive human cases from Madera, Merced, San Bernardino, Stanislaus, and Sutter counties this year.
6 WNV-related fatalities have been reported to CDPH this year from 5 jurisdictions: Butte (2), Glenn (1), Kings (1), Los Angeles (1), and Sacramento (1).
86 human cases from 21 counties have tested positive for WNV in 2026.
Dead Birds
Year-to-date: 512 Counties: 23
There were 31 new WNV positive dead birds reported in California this week from the following counties: Alameda (1), Contra Costa (1), Los Angeles (14), Madera (1), Sacramento (2), San Bernardino (1), San Diego (4), San Joaquin (2), Santa Clara (4), and Yolo (1).
512 dead birds from 23 counties have tested positive for WNV in 2026.
Mosquito Samples
Year-to-date: 3231 Counties: 29
There were 230 new WNV positive mosquito samples reported in California this week from the following counties: Butte (9), Fresno (2), Kern (4), Los Angeles (72), Madera (17), Merced (18), Orange (29), Placer (1), Riverside (11), Sacramento (3), San Bernardino (18), San Diego (6), San Joaquin (8), Solano (2), Stanislaus (7), Tulare (20), and Yolo (3).
3,231 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: 114 Counties: 9
There were 8 new WNV positive sentinel chickens reported in California this week from the following counties: Los Angeles (5), Shasta (1), and Tulare (2).
114 sentinel chickens from 9 counties have tested positive for WNV in 2026.
Horses
Year-to-date: 10 Counties: 10
There have been 2 new WNV positive horses reported in California this week from Sacramento (1) and Sutter (1) counties. These are the first WNV positive horses from Sacramento and Sutter counties this year.
10 horses from 10 counties have tested positive for WNV in 2026.