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Sunnyvale West Nile Virus Treatment Aug. 25

The County of Santa Clara Vector Control District has confirmed the presence of West Nile virus-positive mosquitoes in a small area of Sunnyvale and Cupertino (ZIP Codes 94086, 94087 and 95014). Weather permitting, the areas in Sunnyvale and Cupertino will be treated to reduce adult mosquito populations with the use of truck-mounted equipment on Thursday, Aug. 25, starting around 10 p.m. and concluding a few hours later.

This is the second time the County of Santa Clara Vector Control District has treated the City of Sunnyvale. Earlier this month, the agency treated another area of Sunnyvale on Aug. 4. Treatments have also occurred in Cupertino this year.

The District’s mosquito management program largely focuses on preventing mosquitoes from reaching the adult biting stage by proactively targeting immature stages of mosquitoes found in standing water. When a mosquito with West Nile virus (WNV) is detected, however, the District takes the added step of conducting an adult mosquito control treatment to reduce the mosquito population in the area, which reduces the risk of a WNV-human infection.


It is normal to see an increase in West Nile virus during the summer because mosquitoes thrive in hot weather. The District has a dedicated surveillance program to detect the presence of diseases like West Nile virus, 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.

The Vector Control 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.

Notice is being sent directly to the public in the treatment ZIP codes in Sunnyvale and Cupertino 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 p.m. Questions can also be submitted by email to

Area of Operation for West Nile Virus Treatment

The specific details of the operational areas are:

  • Treatment date: Thursday, Aug. 25, around 10 p.m., for approximately four hours
  • Supervisorial Districts: Districts 3 and 5
  • Cities: Sunnyvale and Cupertino
  • Centered at: Carlisle Way and Flicker Way

Bordered by:

  • North – Mesquite Place, Ponderosa Avenue, Poplar Avenue, Henderson Way, Spoonbill Way, Teal Drive, Prince Edward Way, Cordilleras Avenue, Hollenback Avenue, Sesame Drive, Tangerine Way, Tilton Drive, Sunnyvale-Saratoga Road, Goya Drive, Brahms Way, Cezanne Drive and South Fair Oaks Avenue
  • East – Iris Avenue, Larkspur Avenue, Rosa Avenue, Bryant Way, Cascade Drive, West Fremont Avenue, Vanderbilt Drive, Torrington Drive, Templeton Drive, Rockport Drive, West Remington Drive, Cumulus Avenue and state Route 82
  • South – Lochinvar Avenue, Quail Avenue, Peacock Avenue, Linnet Lane, North De Anza Boulevard, Tenaka Place and Revelstoke Way
  • West – Inverness Way, Lorne Way, Homestead Road, La Conner Drive, Conner Drive, Fort Laramie Drive, Cheyenne Drive and Interstate Highway 280

ZIP Codes affected: Parts of 94086, 94087 and 95014

Interactive map:

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 in the Sunnyvale and Cupertino treatment areas can keep family and pets inside during the treatment, with windows and doors shut during the duration of the control treatment (approximately four 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 at 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, go to

Health Effects of West Nile Virus

Since West Nile virus arrived in California in 2003, more than 7,000 people across the state have contracted the disease; nearly 400 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. Individuals with certain chronic medical conditions (such as diabetes, high blood pressure, cancer and kidney disease) and the elderly are most at risk for serious complications.

Preventative Measures

The public can assist in preventing the spread of West Nile virus by taking the following prevention measures.

On your property:

  • Inspect for standing water on a weekly basis.
  • Drain or turn over anything that can hold water, such as flowerpots, planter bases, pet dishes, buckets and old tires.
  • Clean items like bird baths and pet bowls once a week to remove mosquito eggs.
  • Clear debris from rain gutters on a regular basis to allow water to flow.
  • Properly screen rain barrels, cisterns and irrigation drains to prevent mosquito access.
  • Fix leaky water faucets and broken sprinkler heads and avoid overwatering lawns and plants.
  • Ensure window and door screens are in good condition with no holes or tears and are tight-fitting.
  • Ensure swimming pool water level is adequate for proper circulation and filtration.

Free mosquitofish can be requested online at for placement in neglected pools/spas, ornamental ponds, water troughs and other artificial bodies of water. For more information on our mosquitofish program, visit

Outdoor Activities:

  • Limit outdoor activities during dusk and dawn – these are the times when the mosquitoes that transmit WNV are most active.
  • If spending time outdoors, dress in long-sleeve shirts and long pants, preferably in light colors – mosquitoes are mostly attracted to dark colors.
  • Apply insect repellent that contains DEET, IR3535, or Oil of Lemon Eucalyptus, always following label instructions.

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


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