HAYWARD, CA March 20, 2025

The Alameda County Mosquito Abatement District is reporting a dead bird that tested positive for West Nile virus. This is the County's first indication of West Nile virus this year.  The dead bird was collected from Castro Valley, near the Castro Valley Community Park and tested at the District laboratory on March 18, 2025 and confirmed on March 20th, 2025.

The District is increasing mosquito monitoring and larval control efforts throughout the area where the West Nile virus positive bird was discovered. Every effort is being made to locate areas of standing water where mosquitoes may breed including but not limited to catchbasins, stormdrain systems, and unmaintained swimming pools. If you or anyone you know has an unmaintained swimming pool please inform the District so the proper treatment can be made.

"With spring here, we’ll start seeing more mosquitoes across the state," says ACMAD Lab Director Eric Haas-Stapleton, PhD. "The rain and sunshine we’ve had over the last three months create ideal conditions for mosquitoes to grow in standing water. One of the first signs that West Nile virus is spreading in an area is the presence of dead birds, and we appreciate the public’s help in reporting them. If you see a dead bird, no matter where, please contact the California Dead Bird Hotline either by phone or online at https://westnile.ca.gov/report.php. The best way to reduce the risk of West Nile virus is to prevent mosquitoes from developing in the first place. Residents can help by draining, treating, or covering any containers that hold water—or by reaching out to our district if there is standing water in their neighborhood."

Reduce the risk of contracting mosquito-borne diseases by

following these guidelines:

* DUMP/DRAIN standing water on your property, since mosquitoes need water to develop.

* DAWN/DUSK is when mosquito activity peaks, so limit outdoor activities during this time.

* DEFEND yourself from mosquito bites by wearing long pants and long-sleeved shirts and apply insect repellent containing EPA-registered active ingredients such as DEET, Picaridin, IR3535, or Oil of lemon eucalyptus.

* DOOR/window screens should be in good repair with no tears or holes.

West Nile virus is transmitted to people and animals through the bite of an infected mosquito. Approximately one in five people who are infected with West Nile virus will develop symptoms such as fever, headache, body aches, joint pains, vomiting, or rash. Less than one percent will develop a serious neurological illness such as encephalitis or meningitis. There is no cure for West Nile virus.  Adults over 50 years old and people with compromised immune systems are at increased risk of serious complications. Anyone who develops symptoms should seek medical care immediately.

Horses are very susceptible to West Nile virus and vaccines are available. Horse owners are advised to contact their veterinarians regarding timely vaccinations.

For information about mosquitoes, West Nile virus, or to request any of the District services visit www.mosquitoes.org or call (510) 783-7744. Residents can also request mosquitofish for their fish ponds, horse troughs, or neglected swimming pools at the District office located in Hayward at 23187 Connecticut St. For information concerning West Nile virus symptoms, prevention or testing please contact the Alameda County Public Health Department at (510) 267-8001.

About Alameda County Mosquito Abatement District

Alameda County Mosquito Abatement District is committed to improving the health and comfort of Alameda County residents by controlling mosquitoes and limiting the transmission of mosquito-borne diseases. Learn more about our work at www.mosquitoes.org

Media Contact:

Name: Judith Pierce

Title: Public Education Officer

Phone: 510-783-7744

Email address: judith@mosquitoes.org