Human Cases
Year-to-date: 2 Counties: 2
There was 1 new WNV positive human case reported in California this week from Sacramento County. This is the first WNV positive human case from Sacramento County this year.
2 human cases from 2 counties have tested positive for WNV in 2026.
Dead Birds
Year-to-date: 178 Counties: 15
There were 45 new WNV positive dead birds reported in California this week from the following counties: Alameda (5), Fresno (1), Los Angeles (5), Placer (1), Riverside (1), Sacramento (17), San Bernardino (2), San Diego (2), San Mateo (3), Santa Clara (7), and Yolo (1). This is the first WNV positive dead bird from Riverside County this year.
178 dead birds from 15 counties have tested positive for WNV in 2026.
Mosquito Samples
Year-to-date: 433 Counties: 22
There were 172 new WNV positive mosquito samples reported in California this week from the following counties: Alameda (1), Butte (1), Fresno (11), Imperial (3), Kern (7), Kings (6), Los Angeles (9), Madera (49), Merced (2), Orange (34), Placer (3), Riverside (6), Sacramento (15), San Diego (1), San Joaquin (1), Stanislaus (2), Tulare (17), Ventura (1), Yolo (1), and Yuba (2). These are the first WNV positive mosquito samples from Placer, San Diego, Ventura, and Yolo counties this year.
This is the first indication of WNV from Yuba County this year.
433 mosquito samples from 22 counties have tested positive for WNV in 2026.
A mosquito sample may contain up to 50 individual mosquitoes.
Sentinel Chickens
Year-to-date: 0 Counties:
No sentinel chickens have tested positive for WNV in 2026.
Horses
Year-to-date: 1 Counties: 1
1 horse from 1 county has tested positive for WNV in 2026.