West Nile Virus in California
As of September 2026, California has 6 West Nile Virus alerts in the past 30 days (6 confirmed cases).
Risk Level
🟠 Elevated
Multiple cases — enhanced biosecurity recommended
Cases (30 days)
6
Total Cases
27
Counties Affected
19
Most recent West Nile Virus alert in California: Sep 17, 2026
West Nile Virus Alerts in California
Amador, California
Sep 17, 2026 · active
1
confirmed
Shasta, California
Sep 16, 2026 · active
1
confirmed
El Dorado, California
Sep 14, 2026 · active
1
confirmed
Amador, California
Sep 11, 2026 · active
1
confirmed
Sacramento, California
Sep 5, 2026 · active
1
confirmed
Sutter, California
Sep 5, 2026 · active
1
confirmed
Contra Costa, California
Aug 28, 2026 · active
1
confirmed
Stanislaus, California
Aug 25, 2026 · active
1
confirmed
Fresno, California
Aug 17, 2026 · active
1
confirmed
Placer, California
Aug 10, 2026 · active
1
confirmed
Merced, California
Aug 6, 2026 · active
1
confirmed
Kings, California
Jul 31, 2026 · active
1
confirmed
Sacramento, California
Jul 29, 2026 · active
1
confirmed
San Luis Obispo, California
Jun 16, 2026 · active
1
confirmed
Sacramento, California
Sep 30, 2025 · active
1
confirmed
Sacramento, California
Sep 30, 2025 · active
1
confirmed
Yolo, California
Sep 24, 2025 · active
1
confirmed
Stanislaus, California
Sep 18, 2025 · active
1
confirmed
Contra Costa, California
Sep 17, 2025 · active
1
confirmed
Santa Barbara, California
Sep 2, 2025 · active
1
confirmed
Tehama, California
Oct 11, 2024 · active
1
confirmed
Los Angeles, California
Sep 9, 2024 · active
1
confirmed
San Diego, California
Aug 26, 2024 · active
1
confirmed
San Joaquin, California
Aug 14, 2024 · active
1
confirmed
Sacramento, California
Aug 3, 2024 · active
1
confirmed
Showing the 25 most recent of 27 total alerts.
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