The Silicon Valley Voice

Power To Your Voice

Positive West Nile Virus Mosquitoes Found in Portions of Sunnyvale and Santa Clara

The County of Santa Clara Vector Control District has confirmed the presence of positive West Nile virus mosquitoes in areas of Sunnyvale and Santa Clara (ZIP Codes 94085, 94086, 94087 and 95051). Weather permitting, this area in Santa Clara and Sunnyvale will be treated to reduce adult mosquito populations with the use of truck-mounted equipment on Monday, July 11, starting around 10 p.m. and concluding a few hours later.

The Vector Control District has a dedicated surveillance program to detect the presence of diseases like West Nile virus (WNV), St. Louis encephalitis and western equine encephalitis, all of which are transmitted through the bite of infected mosquitoes. The data collected through surveillance is used to predict locations that are more likely to have these disease-transmitting mosquitoes. When positive West Nile virus mosquitoes are detected, the District initiates an adult mosquito control treatment to reduce the mosquito population in the area, which reduces the risk of a WNV human infection.

The District has been conducting truck-mounted treatments regularly since 2003 to successfully reduce WNV-transmitting mosquito populations. The District will be adhering to requirements and recommendations from the County of Santa Clara Public Health Department for COVID-19.


Distribution of door hangers notifying the affected Santa Clara and Sunnyvale neighborhoods of the scheduled West Nile virus mosquitoes treatment began Tuesday, July 5. Additional notice is being sent directly to the public in the treatment ZIP codes through AlertSCC and to those who subscribe to Nextdoor neighborhood networks. General notice is being provided on various social media platforms –including Facebook, Instagram and Twitter (@SCCVCD) – and to those subscribed to the District’s mosquito treatment notifications.

Vector Control staff will be available to answer any questions from the public, Monday–Friday, on the dedicated West Nile Virus Hotline at (408) 282-3114, from 7:30 a.m. to 4:00 p.m. Questions can also be submitted by email to

Details of Treatment Area

Treatment date: Monday, July 11, around 10 p.m., for approximately three hours

Supervisorial Districts: Districts 3 and 4

Cities: Sunnyvale and Santa Clara

Centered at: Ajax Drive and Joshua Way

Bordered by:

  • North – N. Fair Oaks Avenue, De Guigne Drive, Willow Avenue, San Zeno Way, Morse Avenue, N. Sunnyvale Avenue, N. Frances Street, and Aries Way
  • East – Steward Drive, E. Arques Avenue, E. Maude Avenue, E. Taylor Avenue, and Olson Way
  • South – S. Taaffe Street, Azure Street, Sunnyvale-Saratoga Road, Manet Drive, Rembrandt Drive, Ponderosa Avenue, Poplar Avenue, Henderson Avenue, Sugarpine Avenue, Timberpine Avenue, and Willow Avenue
  • West – W. California Avenue, Azure Street, Crescent Avenue, Remington Drive, Chopin Drive, Maria Lane, Rosa Avenue, Lily Avenue, Reed Avenue, Nettle Place, Paintbrush Drive, and Willow Avenue
  • ZIP Codes affected: Parts of 94085, 94086, 94087 and 95051

You can find an interactive map of the affected area here.

There is no need to relocate during the treatment. Mosquito treatments pose minimal risk to people, pets, animals, and the environment when applied by a licensed vector control professional following label instructions. Those who would like to take extra precautions can keep family and pets inside during the treatment, with windows and doors shut during the duration of the control treatment (approximately three hours). By sunrise, the insecticide will quickly break down with the sunlight. Since the District applies insecticides at Ultra-Low Volume (ULV), individuals aren’t likely to breathe or touch anything that has enough insecticide on it to be harmful. Those with chemical sensitivities may want to consult their physicians for additional recommendations. All control materials utilized in our mosquito control program are approved by the Federal and State Environmental Protection Agencies and are widely used by Vector Control agencies throughout California.

For more information on the products used for this mosquito control treatment, including the safety data sheet, insecticide label and a list of our most frequently asked questions, please visit our website For additional information on adulticides, visit the Centers for Disease Control and Prevention’s website at For information on West Nile virus activity in California, please visit the state’s website.

Health Effects of West Nile Virus

Since West Nile virus arrived in California in 2003, 7,474 people across the State have contracted the disease; 359 of those cases were fatal. In 2021, there were 12 human WNV-related deaths; 2015 was a record year for fatalities in the state with 55 deaths.

WNV infection does not cause symptoms in most people; however, for some individuals it can cause fever, headache, body aches and, in severe cases, significant neurological damage or death. Adults older than 50 years and individuals with certain chronic medical conditions such as diabetes, high blood pressure, cancer and kidney disease are most at risk for serious complications.

The District has a dedicated team that inspects locations throughout the county for mosquito breeding, searches for new breeding sources, and eliminates any immature stages of mosquitoes. The public can also assist in preventing the spread of West Nile virus by taking the following prevention measures.

On your property:

  • Dump or drain standing water weekly. Mosquitoes need stagnant water to lay their eggs and spend three out of four life stages in water.
  • Drain, remove or turn over anything that can hold water, such as flowerpots, planter bases, bird baths, toys, cans, rain gutters, pet dishes, buckets and old tires. Fix leaky water faucets and sprinklers. For more information on water conservation and mosquito prevention, visit
  • Screens on doors and windows should be tight-fitting and in good condition.
  • Do not let your swimming pool water fall below the pump circulation area. Free mosquitofish can be requested online at for placement in neglected pools or ornamental ponds. For more information on our mosquitofish program, please visit

Outdoor Activities:

  • Limit outdoor activities during DUSK and DAWN to prevent mosquito bites. Those are the times when the mosquitoes that transmit WNV are most active.
  • If you need to go outside in an area where mosquitoes are active:
  • Dress in long-sleeve shirts and long pants, preferably in light colors
  • Apply insect repellent approved by the Environmental Protection Agency, following label instructions. For more information on mosquitoes, visit

Contact the County of Santa Clara Vector Control District if you are being bothered by mosquitoes or know of a potential mosquito-breeding source. For free assistance with mosquito control or other vectors, residents can contact the District office main line at (408) 918-4770 or fill out a service request online at


Leave a Comment

Your email address will not be published.


You may like