Human Cases
Year-to-date: 452 Counties: 24
There were 74 new WNV positive human cases reported in California this week from the following counties: Fresno (2), Los Angeles (59), Orange (10), San Joaquin (1), Stanislaus (1), and Tulare (1).
29 WNV-related fatalities have been reported to CDPH this year from 9 jurisdictions: Butte (3), Glenn (2), Kings (1), Los Angeles (10), Orange (7), Sacramento (2), Stanislaus (1), Tuolumne (1), and Yolo (2).
452 human cases from 24 counties have tested positive for WNV in 2026.
Dead Birds
Year-to-date: 753 Counties: 25
There were 19 new WNV positive dead birds reported in California this week from the following counties: Contra Costa (2), Los Angeles (2), San Bernardino (1), San Diego (9), San Mateo (1), Santa Clara (3), and Yuba (1).
753 dead birds from 25 counties have tested positive for WNV in 2026.
Mosquito Samples
Year-to-date: 4075 Counties: 29
There were 70 new WNV positive mosquito samples reported in California this week from the following counties: Butte (1), Los Angeles (41), Orange (15), Riverside (4), Sacramento (1), San Bernardino (1), San Diego (6), and San Joaquin (1).
4,075 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
149 sentinel chickens from 11 counties have tested positive for WNV in 2026.
Horses
Year-to-date: 17 Counties: 14
There have been 2 new WNV positive horses reported in California last week from Sacramento (1) and Siskiyou (1) counties. This is the first indication of WNV from Siskiyou County this year.
17 horses from 14 counties have tested positive for WNV in 2026.