Yellow Fever Mosquito Found in San Mateo County

This mosquito, which can transmit a number of viruses including yellow fever, was previously found in San Mateo County in 1979 near SFO.

Yellow fever mosquito. Credit: Wikipedia
Yellow fever mosquito. Credit: Wikipedia

State officials confirmed Friday a yellow fever mosquito, which can transmit a number of viruses including yellow fever, was found in San Mateo County.

The last time a yellow fever mosquito was confirmed in San Mateo County was in 1979.

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 pools.by 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.

margaret jones August 24, 2013 at 09:28 AM
Your article failed to mention symptoms and treatment if infected. What's interesting is those who recover from yellow fever generally have lasting immunity against subsequent infection. Below is what the Center for Disease Control & Prevention (CDC) web page states: Yellow Fever Symptoms and Treatment Symptoms: The majority of persons infected with yellow fever virus have no illness or only mild illness. In persons who develop symptoms, the incubation period (time from infection until illness) is typically 3–6 days. The initial symptoms include sudden onset of fever, chills, severe headache, back pain, general body aches, nausea, and vomiting, fatigue, and weakness. Most persons improve after the initial presentation. After a brief remission of hours to a day, roughly 15% of cases progress to develop a more severe form of the disease. The severe form is characterized by high fever, jaundice, bleeding, and eventually shock and failure of multiple organs. Treatment: No specific treatments have been found to benefit patients with yellow fever. Whenever possible, yellow fever patients should be hospitalized for supportive care and close observation. Treatment is symptomatic. Rest, fluids, and use of pain relievers and medication to reduce fever may relieve symptoms of aching and fever. Care should be taken to avoid certain medications, such as aspirin or other nonsteroidal anti-inflammatory drugs (e.g. ibuprofen, naproxen), which may increase the risk of bleeding. Yellow fever patients should be protected from further mosquito exposure (staying indoors and/or under a mosquito net) during the first few days of illness. This way, yellow fever virus in their bloodstream will be unavailable to other uninfected mosquitoes, thus breaking the transmission cycle and reducing risk to the persons around them. Outcome: The majority of infected persons will be asymptomatic or have mild disease with complete recovery. -In persons who become symptomatic but recover, weakness and fatigue may last several months. -Among those who develop severe disease, 20% - 50% may die. -Those who recover from yellow fever generally have lasting immunity against subsequent infection.
Gladwyn d'Souza August 24, 2013 at 11:10 AM
Good work Dr. Morrow and San Mateo County Mosquito and Vector Control District- you get the needle in haystack finding award. These peninsula hills must have sufficient potholes and backyards for a million breeding spots. One of the nice aspects of the peninsula is our generally bothersome insect free backyards.


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