Human Cases
Year-to-date: 22 Counties: 8
There were 5 new WNV positive human cases reported in California this week from the following counties: Butte (1), Kern (3), and Tulare (1).
1 WNV-related fatalities have been reported to CDPH this year from 1 jurisdiction: Tulare (1)
22 human cases from 8 counties have tested positive for WNV in 2025.
Dead Birds
Year-to-date: 111 Counties: 16
There were 14 new WNV positive dead birds reported in California this week from the following counties: Fresno (2), Los Angeles (1), Sacramento (4), San Diego (2), San Joaquin (1), Santa Clara (1), Solano (1), Sutter (1), and Yolo (1). These are the first WNV positive dead birds from Sutter and Yolo counties this year.
111 dead birds from 16 counties have tested positive for WNV in 2025.
Mosquito Samples
Year-to-date: 1,912 Counties: 27
There were 200 new WNV positive mosquito samples reported in California this week from the following counties: Butte (4), Fresno (14), Kern (5), Kings (7), Lake (1), Los Angeles (18), Madera (15), Orange (9), Placer (19), Sacramento (5), San Joaquin (19), Santa Clara (2), Solano (8), Stanislaus (26), Sutter (1), Tulare (35), Yolo (11), and Yuba (1). This is the first WNV positive mosquito sample from Santa Clara County this year.
1,912 mosquito samples from 27 counties have tested positive for WNV in 2025.
A mosquito sample may contain up to 50 individual mosquitoes.
Sentinel Chickens
Year-to-date: 25 Counties: 6
There were 5 new WNV positive sentinel chickens reported in California this week from the following counties: Butte (1), Lake (1), Sutter (1), and Yuba (2).
25 sentinel chickens from 6 counties have tested positive for WNV in 2025.
Horses
Year-to-date: 0 Counties:
No horses have tested positive for WNV in 2025.