Tropical Yellow-fever Mosquito found in Menlo Park


Yellow Fever Mosquito Found in San Mateo County

SAN MATEO, Calif. – On August 23rd, California Department of Public Health confirmed the identification of a yellow fever mosquito (Aedes aegypti). San Mateo County Mosquito and Vector Control District found the mosquito this week at Holy Cross cemetery in a residential area of the city of Menlo Park.  The Aedes aegypti species is not native to California; however it is a common mosquito in urban areas of the southeastern United States.  The yellow fever mosquito has the potential to transmit several viruses, including dengue and yellow fever. This type of mosquito was found earlier this summer in the counties of Fresno and Madera; no illnesses associated with this mosquito have been reported so far.

The San Mateo County Mosquito and Vector Control District is working closely with San Mateo County Health System, the California Department of Public Health, and Santa Clara County Vector Control District to evaluate the extent of the infestation and aggressively target problem areas to prevent its spread.

“Our goal is to quickly eradicate this mosquito population.” said Robert Gay for San Mateo County Mosquito and Vector Control District. “We will do everything to help ensure this mosquito does not become established in our communities.”

The Mosquito and Vector Control District will expand surveillance efforts for this type of mosquito.  The district will deploy a variety of traps for adult mosquitoes and mosquito eggs surrounding the location where the Aedes aegypti mosquito was found.   Additionally, District staff will be conducting door to door inspections of homes and providing educational materials to residents in the neighborhood.

The Aedes aegypti species is a tiny (about ¼ inch) black and white mosquito that bites most often during the day, and can transmit dengue, yellow fever, chikungunya, and several viruses that cause encephalitis. These viruses are not currently found in California.

This mosquito was previously found in San Mateo County in 1979 near SFO, but was successfully eradicated by the Mosquito and Vector Control District and did not become established here.

“It’s important to note that the current risk of disease transmission from this mosquito is extremely low”, said Dr. Scott Morrow, Health Officer for San Mateo County. “But we must make every effort to eradicate this mosquito and not allow it to establish itself here to prevent future disease transmission risk.  The public can really play a critical role in helping to control the spread of this mosquito population. The yellow fever mosquito lays its eggs in water, just above the water line in small containers and vessels that hold water, such as pots, pet bowls, bottles, and bird baths. It’s important to survey your yard and around your house to eliminate even the smallest amount of standing water.”

It’s important to avoid mosquito bites or reduce the chances of being bitten by taking the following precautions:

  • Apply insect repellents that contain DEET, picaridin, oil of lemon eucalyptus or IR 3535 and follow label instructions.
  • Make sure that doors and windows have tight-fitting screens to keep out mosquitoes and repair or replace screens with tears or holes.
  • Eliminate standing water and containers that can hold water from around the home.
  • Report neglected swimming calling San Mateo County Mosquito and Vector Control (650) 344-8592 or the Santa Clara Vector Control District (408) 918-4770.
  • Wear long sleeve shirts and long pants when possible.
  • Use mosquito netting over infant carriers, cribs and strollers.

Residents experiencing mosquito bites during the day should report them to the San Mateo County Mosquito and Vector Control District (650) 344-8592 or the Santa Clara Vector Control District (408) 918-4770.

“The fact that our County’s Mosquito and Vector Control District discovered the existence of this mosquito, speaks to their high level of sophistication and technical expertise,” said Dr. Morrow. “I am very impressed and on behalf of our residents, thankful.”

Additional information can be found at:
San Mateo County Mosquito and Vector Control District:, (650) 344-8592
California Department of Public Health:
San Mateo County Health System:



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