HAYWARD, CA - 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 active virus transmission in 2021. The dead bird was collected from Pleasanton, CA and tested at the District laboratory on September 27, 2021. Dead birds play an important role in the District's ability to monitor West Nile virus activity in Alameda County. Public reporting of dead birds is vital to our surveillance program. 

The District is increasing mosquito monitoring and larval control efforts throughout the area where the positive West Nile virus dead 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 swimming pools. Anything that can hold water for more than 4 days such as buckets, tires, and fountains can breed mosquitoes. 

“With the change of season, residents may assume mosquitoes are no longer a threat, but this is usually the time of year when we see an increase in West Nile virus in our county, “ says General Manager Ryan Clausnitzer. “With light showers in the mornings followed by warm weather in the afternoons, mosquitoes still have plenty of opportunities to breed and flourish. We wish to remind residents to do their part by removing standing water from their property and protect themselves from mosquito bites by wearing repellent and long and loose clothing. While we are not detecting high numbers of mosquitoes in the area where the bird was found, there is an increased risk of West Nile virus with every mosquito bite.”

As of September 27, 2021 California has had 192 dead birds, 2,126 mosquito samples, and 57 humans test positive for West Nile virus.  

Reduce the risk of contracting mosquito-borne diseases by following these guidelines:

DUMP/DRAIN standing water on your property because that is where mosquitoes develop.

• DAWN/DUSK is when mosquito activity peaks, 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. There is no cure for West Nile virus. 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. 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. For information concerning West Nile virus symptoms, prevention or testing please contact the Alameda County Public Health Department at (510) 267-8001.