Human Cases
Year-to-date: 2 Counties: 2
There was 1 new WNV positive human case reported in California last 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: 205 Counties: 18
There were 27 new WNV positive dead birds reported in California this week from the following counties: Alameda (2), Contra Costa (1), Fresno (1), Los Angeles (2), Napa (1), Orange (1), Placer (1), Sacramento (5), San Bernardino (1), San Joaquin (2), San Mateo (1), Santa Clara (7), Solano (1), and Ventura (1). This is the first WNV positive dead bird from Orange County this year.
This is the first indication of WNV from Napa and Solano counties this year.
205 dead birds from 18 counties have tested positive for WNV in 2026.
Mosquito Samples
Year-to-date: 670 Counties: 23
There were 237 new WNV positive mosquito samples reported in California this week from the following counties: Butte (2), Fresno (13), Kern (6), Kings (12), Los Angeles (28), Madera (57), Orange (31), Placer (6), Riverside (4), Sacramento (9), San Bernardino (15), San Joaquin (15), Stanislaus (3), Sutter (3), Tulare (30), and Yolo (3). This is the first indication of WNV from Sutter County this year.
670 mosquito samples from 23 counties have tested positive for WNV in 2026.
A mosquito sample may contain up to 50 individual mosquitoes.
Sentinel Chickens
Year-to-date: 2 Counties: 1
There were 2 new WNV positive sentinel chickens reported in California this week from Los Angeles County. This is the first WNV positive sentinel chicken from Los Angeles County this year.
2 sentinel chickens from 1 county 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.