Invasive Aedes mosquitoes are not native to San Mateo County, California, or even North America. They do not belong in our ecosystems, and they can make people very uncomfortable because they bite during the day and even bite indoors. More importantly, they are a risk to human health because they can carry diseases that make people very sick, like Zika, chikungunya, dengue, and yellow fever.
Species of invasive Aedes mosquitoes are found in some areas of Arizona and California. One species, Aedes aegypti, has been found in San Mateo County before, but have not been seen here since May of 2015. This interactive map by the California Department of Public Health shows where they are currently found in our state.
Although invasive Aedes mosquitoes have not been seen in our county recently, there is a high risk that they will be brought into our county again. These mosquitoes are spreading throughout California and have been found as close by as Fresno, Merced, and Madera Counties.
The District continues to conduct intensive surveillance throughout the county, but you can help out by reporting suspected invasive Aedes mosquito sightings. The sooner we know that these invasive mosquitoes have arrived in our county, the better chance we have of stopping them.