Human Cases
Year-to-date: 210 Counties: 23
There were 64 new WNV positive human cases reported in California this week from the following counties: Fresno (2), Kings (2), Los Angeles (42), Merced (1), Orange (9), Placer (1), San Bernardino (1), San Joaquin (3), San Luis Obispo (1), Santa Clara (1), and Yuba (1). These are the first WNV positive human cases from Placer and San Luis Obispo counties this year.
15 WNV-related fatalities have been reported to CDPH this year from 7 jurisdictions: Butte (3), Glenn (2), Kings (1), Los Angeles (3), Orange (2), Sacramento (2), and Yolo (2).
210 human cases from 23 counties have tested positive for WNV in 2026.
Dead Birds
Year-to-date: 657 Counties: 24
There were 34 new WNV positive dead birds reported in California this week from the following counties: Alameda (2), Los Angeles (12), Orange (8), Riverside (1), Sacramento (1), San Bernardino (1), San Diego (3), San Joaquin (3), Santa Clara (1), Ventura (1), and Yolo (1).
657 dead birds from 24 counties have tested positive for WNV in 2026.
Mosquito Samples
Year-to-date: 3730 Counties: 29
There were 186 new WNV positive mosquito samples reported in California this week from the following counties: Alameda (1), Fresno (9), Kern (3), Los Angeles (45), Madera (1), Orange (58), Sacramento (2), San Bernardino (5), San Diego (37), San Joaquin (7), Solano (2), Stanislaus (10), Tulare (4), and Yolo (2).
3,730 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: 143 Counties: 10
There were 2 new WNV positive sentinel chickens reported in California this week from Los Angeles County.
143 sentinel chickens from 10 counties have tested positive for WNV in 2026.
Horses
Year-to-date: 14 Counties: 13
There were 3 new WNV positive horses reported in California last week from the following counties: Amador (1), El Dorado (1), and Shasta (1). These are the first WNV positive horses from El Dorado and Shasta counties this year.
14 horses from 13 counties have tested positive for WNV in 2026.