Human Cases
Year-to-date: 11 Counties: 7
There were 6 new WNV positive human cases reported in California this week from the following counties: Butte (2), Kings (1), Santa Clara (1), and Tulare (2). These are the first WNV positive human cases from Butte and Santa Clara counties this year.
11 human cases from 7 counties have tested positive for WNV in 2026.
Dead Birds
Year-to-date: 288 Counties: 20
There were 37 new WNV positive dead birds reported in California this week from the following counties: Alameda (3), Los Angeles (13), Sacramento (5), San Bernardino (1), San Diego (4), San Mateo (2), Santa Clara (5), Solano (1), Yolo (2), and Yuba (1).
288 dead birds from 20 counties have tested positive for WNV in 2026.
Mosquito Samples
Year-to-date: 1464 Counties: 27
There were 464 new WNV positive mosquito samples reported in California this week from the following counties: Butte (8), Fresno (11), Glenn (1), Kern (23), Kings (26), Lake (1), Los Angeles (55), Madera (73), Orange (131), Placer (22), Riverside (5), Sacramento (12), San Bernardino (21), San Diego (2), San Joaquin (12), Santa Clara (2), Shasta (1), Stanislaus (11), Sutter (5), Tulare (25), and Yolo (17). This is the first WNV positive mosquito sample from Santa Clara County this year.
This is the first indication of WNV from Glenn County this year.
1,464 mosquito samples from 27 counties have tested positive for WNV in 2026.
A mosquito sample may contain up to 50 individual mosquitoes.
Sentinel Chickens
Year-to-date: 12 Counties: 5
There were 10 new WNV positive sentinel chickens reported in California this week from the following counties: Butte (4), Los Angeles (2), Sutter (2), Tulare (1), and Yuba (1). These are the first WNV positive sentinel chickens from Butte, Sutter, Tulare, and Yuba counties this year.
12 sentinel chickens from 5 counties have tested positive for WNV in 2026.
Horses
Year-to-date: 3 Counties: 3
There have been 2 new WNV positive horses reported in California this week from Kings (1) and San Joaquin (1) counties. These are the first WNV positive horses from Kings and San Joaquin counties this year.
3 horses from 3 counties have tested positive for WNV in 2026.