West Nile virus (WNV) Activity
Year-to-Date Statistics for 2026
Updated 05/04/2026
2026 WNV+ Mosquito Samples
A sample is a collection of mosquitoes from a mosquito monitoring trap. Positive mosquito samples from routine and randomized trapping provide insight into the spread of West Nile virus.
No detections at this time.
2026 WNV+ Dead Birds
Residents report dead birds through the California Department of Public Health (CDPH) Dead Bird Surveillance program. The District tests the dead birds for West Nile virus when it meets testing criteria. Positive dead birds also provide insight to West Nile virus activity.
| City | Date of First Confirmed Detection | # of WNV+ Birds |
|---|---|---|
| Newark | 05/01/2026 | 1 |
| Total # of WNV Positive Birds this year | 1 |
West Nile Virus Activity (WNV+) in Alameda County
Visit the full VectorSurv site to learn more about mosquito and disease activity throughout California.
West Nile Virus Activity in Alameda County: Past 10-Year Overview
| 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 | 2026 | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Birds | 17 | 2 | 20 | 0 | 8 | 3 | 0 | 82 | 53 | 6 | 1 |
| Mosquitoes | 2 | 0 | 15 | 0 | 0 | 0 | 0 | 22 | 19 | 0 | 0 |
| Humans | 0 | 1 | 0 | 0 | 0 | 0 | 1 | 2 | 0 | 0 | 0 |
Learn more about West Nile virus Activity in California and the United States
To take a look at West Nile virus activity throughout California, visit the California Department of Public Health (CDPH) West Nile virus website (westnile.gov).
To take a look at West Nile virus activity throughout the United States, visit the U.S. Centers for Diseases Control and Prevention (CDC) West Nile virus website (cdc.gov/west-nile-virus/).
Past West Nile virus Activity in Alameda County