Close up of a mosquito feeding on human skin (image courtesy: pexels)
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Close up of a mosquito feeding on human skin (image courtesy: pexels)
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Close up of a mosquito feeding on human skin (image courtesy: pexels)” data-image-caption=”
Close up of a mosquito feeding on human skin (image courtesy: pexels)
” data-medium-file=”https://i0.wp.com/indiacurrents.com/wp-content/uploads/2025/04/pexels-shyamli-kashyap-13140263-28647149.jpg?fit=300%2C169&ssl=1″ data-large-file=”https://i0.wp.com/indiacurrents.com/wp-content/uploads/2025/04/pexels-shyamli-kashyap-13140263-28647149.jpg?fit=780%2C439&ssl=1″ />
SANTA CLARA COUNTY, Calif. – The County of Santa Clara Vector Control District has detected the first invasive Aedes aegypti mosquitoes of 2025 in a South San Jose neighborhood, highlighting the importance of collaboration between County experts and community members in preventing the spread of the day-biting mosquito.
Aedes aegypti is a non-native mosquito that can spread infectious diseases that do not typically occur in the United States, including dengue, chikungunya, Zika, and yellow fever.
The Vector Control District found the mosquitoes in the Santa Teresa neighborhood of South San Jose, one of the locations where Aedes aegypti was detected in 2024. The district trapped 388 of the invasive mosquitoes last year in six locations in the cities of San Jose, Gilroy, and Santa Clara and worked to eliminate the mosquitoes and remove the stagnant water in which they were laying eggs.
County officials are asking the public to help contain the spread of the aggressive mosquito before it can become established in Santa Clara County.
“The fact that we have found Aedes aegypti again in 2025 means it has gained a foothold in our county, and we need to work in partnership with the community to prevent it from spreading,” said Edgar Nolasco, director of the County Consumer and Environmental Protection Agency. “We need a communitywide effort to find and eliminate these mosquitoes. I want to thank the resident who reported a day-biting mosquito to us, which enabled us to set up traps and identify it. That is the kind of vigilance, engagement and partnership that helps the district do its job effectively.”
An aggressive disease-carrying insect
Aedes aegypti 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.
The non-native mosquito originated in Africa and spread to other parts of the world, including Central America, preferring warm weather. Aedes aegypti is established in 22 counties throughout the state, mostly in the Central Valley and Southern California. It has now been detected, but is not established, in four Bay Area counties. Being established means the mosquito has formed a self-sustaining population and is successfully surviving and reproducing in the local environment.
The invasive mosquito is highly aggressive and active during the day, unlike native mosquito populations, which are most active in the morning and evening, when temperatures are cool.
How You Can Help
The Vector Control District and the County Public Health Department urge the public and businesses to report day-biting mosquitoes, remove sources of standing water where they work and live, and allow district staff, when necessary, to access their properties to eliminate mosquitoes and their breeding sources.
The public plays a critical role in stopping the spread of Aedes aegypti mosquitoes. It’s important for residents in Santa Clara County to do the following:
- Allow government mosquito experts to access their yards and properties to check for mosquitoes and treat them as needed.
- Report day-biting mosquitoes immediately to the Vector Control District at (408) 918-4770 or vectorinfo@cep.sccgov.org. Residents can also send photographs of mosquitoes that are alive or dead.
- Dump out any outdoor containers that are filled with water and clean them by scrubbing them with hot, soapy water or a diluted bleach solution. Cleaning and scrubbing bird baths, pet dishes and other containers can remove any lingering Aedes aegypti eggs, which are about half a millimeter in size and look like tiny bits of dirt to the naked eye.
Health risks
“If this mosquito becomes common in Santa Clara County, it will eventually begin to spread diseases,” said Dr. Sarah Rudman, acting health officer for the County of Santa Clara and director of the Public Health Department. “These diseases are dangerous and will change the experience of having a mosquito bite from an inconvenience to a worrisome health risk. To protect the health of your family and your neighbors, please follow the recommendations of the government mosquito experts.”
None of the viruses that potentially can be transmitted by the invasive mosquito have been transmitted within Santa Clara County so far. However, people who live in Santa Clara County and travel internationally are regularly diagnosed after their return with dengue, Zika and chikungunya contracted outside the United States. Cases of dengue in Santa Clara County returning travelers have increased from seven in 2020 to 49 in 2024. These imported cases of disease in international travelers pose a health risk because of the presence of the mosquito. When the invasive mosquito bites a person with dengue, it can then spread dengue to everyone else it bites.
The Vector Control District has conducted robust community outreach and education about Aedes aegypti over the past year along with extensive efforts to trap and kill the mosquitoes. The inspections are provided at no cost. The County has also been running advertisements in areas found to be affected last year to encourage residents to report bites and dump out standing water.
To reduce the population of Aedes aegypti, the district uses pesticides that are approved by the U.S. and California environmental protection agencies and are widely used by vector control agencies throughout the state.
You can subscribe to the County’s emergency alert system, AlertSCC, to receive specific neighborhood notifications about invasive mosquito detections and mosquito treatments happening in your community.
For more information or frequently asked questions on Aedes aegypti, visit the district’s invasive mosquitoes webpage or the California Department of Public Health’s Aedes aegypti and Aedes albopictus webpage.
Photo by Shyamli Kashyap: https://www.pexels.com/photo/close-up-of-mosquito-biting-human-skin-28647149/
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