The County of Santa Clara Vector Control District has discovered non-native Aedes aegypti mosquitoes in a residential area of the city of Santa Clara. The district will soon begin treatment to eradicate the aggressive species of mosquito, which is known to spread diseases such as dengue and yellow fever.
The discovery in Santa Clara comes as the district continues its effort to eliminate the day-biting insect from neighborhoods in East San José and Gilroy. The goal is to thwart the invasive insect from establishing a permanent population.
The district has identified 58 Aedes aegypti (pronounced AY-dees ah-JIP-tie) mosquitoes so far in the area surrounding Agate and Moraine drives in Santa Clara. District staff are carrying out a thorough eradication plan in the surrounding area, trapping adult mosquitoes, inspecting properties to find mosquito larvae and habitat (i.e., standing water), and treating any larvae they find with pesticide. The district will escalate its mosquito-control methods as needed to include backpack spraying, barrier spraying, and wide area larvicide spraying, which is done with the use of truck-mounted equipment and would be conducted in a series of treatments. Control methods may also be escalated to include adult-mosquito-control treatments if necessary.
It’s important for residents to allow district staff to access their properties to check for mosquitoes and treat them as needed. The district urges residents in Santa Clara, Gilroy and East San José to inspect their properties for standing water, which provides breeding habitat for mosquitoes, and remove it.
If Aedes aegypti gains a foothold in Santa Clara County, it will not only threaten public health but also affect our quality of life, as these mosquitoes are highly aggressive and active during the day, unlike native mosquito populations, which are most active in the morning and evening, when temperatures are cool.
It’s unclear if the detections in East San José, Santa Clara and Gilroy are related. The detection in East San José this spring led to increased outreach and education by the Vector Control District and more vigilance and reporting by members of the community. Mosquito activity is increasing with climate change, and Aedes aegypti has now been detected, though it is not yet established, in four Bay Area counties.
“We are doing everything we can to prevent Aedes aegypti from becoming established in Santa Clara County – and we urgently need the public’s help,” said Edgar Nolasco, director of the County of Santa Clara Consumer and Environmental Protection Agency. “It’s very important for residents in affected areas to cooperate with district staff and allow them to inspect their properties for mosquitoes and mosquito habitat.”
For residents who worry about their privacy, the district emphasizes that staff who enter residential properties are not authorized to do anything besides check for mosquitoes and provide mosquito control as needed. The inspections are provided at no cost to residents.
Officials from the Vector Control District will hold a community meeting on Wednesday, Oct. 2, to inform residents about the treatments and answer their questions. The meeting will take place at 7 p.m. in the multipurpose room of Bracher Elementary School, located at 2700 Chromite Drive in Santa Clara.
Though it is not native to California, Aedes aegypti is present in 19 counties throughout the state, mostly in the Central Valley and Southern California. It has the potential to transmit several viruses, including those that cause dengue, chikungunya, Zika and yellow fever. These viruses are not endemic to California, but there have been occasional cases of these diseases being transmitted by travelers returning from parts of the world where the viruses are prevalent.
The invasive species is about a quarter-inch in size with black and white stripes on its back and legs. It feeds almost exclusively on humans and does not fly long distances, venturing fewer than 500 feet from where it hatches.
Aedes aegypti is aggressive and bites at any time of day. These mosquitoes are “container breeders,” preferring to lay their eggs just above the water line in small, artificial sources of water such as buckets, pet dishes, fountains and bird baths, plant pots and saucers, and old tires. Once laid, the eggs can last for more than a year without water.
The public plays a critical role in controlling the spread of this mosquito. Residents should look around their property and dump out even the smallest amount of standing water. Cleaning and scrubbing bird baths, pet dishes and other containers is a good way to remove any lingering Aedes aegypti eggs, which are about half a millimeter in size and look to the naked eye like tiny bits of dirt.
Residents should also:
- 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.
- Make sure the water level of swimming pools is adequate for proper circulation and filtration.
To protect yourself from mosquito bites:
- Apply insect repellents containing EPA-registered ingredients such as DEET, picaridin, IR3535 or oil of lemon eucalyptus, always following label instructions.
- Wear long-sleeve shirts, pants, socks and shoes when mosquitoes are most active.
- Make sure your window and door screens are in good condition.
Residents experiencing mosquito bites during the day should report them immediately to the Vector Control District at (408) 918-4770 or vectorinfo@cep.sccgov.org. The district encourages residents to email photographs of mosquitoes with black and white stripes to the same address.
If you are sick with fever, headache and joint or muscle pain after returning from an area where dengue, chikungunya, yellow fever or Zika occurs, contact your doctor, and stay indoors as much as possible to avoid mosquito bites and help prevent the possible spread of the virus.
To reduce the population of Aedes aegypti, the district uses pesticides that are approved by the Federal and State environmental protection agencies and are widely used by vector control agencies throughout California.
The California Department of Public Health tests the mosquitoes the district traps for any viruses. To date, none of the viruses that potentially can be transmitted by Aedes aegypti mosquitoes have been transmitted in Santa Clara County.
The County Public Health Department monitors for the occurrence of viruses transmitted by Aedes aegypti and any unusual diseases in partnership with local medical providers and laboratories, who are required to report certain diseases and conditions to Public Health.
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