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Locally-acquired Dengue virus in southern California.

Since October 2023, there have been 22 confirmed cases of residents in southern California becoming infected with Dengue virus after being bitten locally by an invasive Aedes mosquito. Eighteen (18) of these cases occurred in 2024 between August and October.

Previously, all documented human cases of infection with this virus in California occurred in residents who traveled out-of-state and were bitten by an infected mosquito. The recent occurrence of residents getting infected locally is extremely concerning.

Fortunately, the Aedes mosquito species that vector Dengue virus currently are not found in Santa Barbara County - although they may show up anytime since they are widespread in southern California and the Central Valley. 

Please contact us immediately if you find yourselves being bitten by aggressive mosquitoes during the day - especially if they're biting around your ankles and feet.

More about Dengue:

Statement from the San Gabriel Valley Mosquito & Vector Control District: Dengue in Baldwin Park and El Monte, CA

Detailed information on Dengue from the California Department of Public Health: Dengue - What You Need to Know

Information from the National Centers for Disease Control: CDC -About Dengue

A yellow fever mosquito feeding and filling up with blood.
A Yellow Fever mosquito, Aedes aegypti: This mosquito, and the closely related Asian Tiger mosquito, Aedes albopictus, are found throughout Southern California. They are vectors of Dengue, Zika, Chikungunya and Yellow fever viruses. However, they are not found in Santa Barbara County.
Map of Southern California area with yellow stars marking locations of confirmed cases of locally-acquired Dengue virus infections.
Locations of confirmed cases of locally-acquired Dengue virus from infected invasive Aedes mosquitoes.
Map shows distribution of Aedes aegypti and Aedes albopictus mosquitoes by California county, with photos of the two mosquito species.
Distribution of invasive Aedes mosquitoes in California, as of April 2025. 

Map modifed from the California Dept. of Public Health: Invasive Aedes Distribution Map