BRENTWOOD, CA — A type of invasive mosquito that can potentially spread viruses from person to person was recently detected in another city in Contra Costa County.
County officials confirmed Friday that mosquitoes had been trapped in the city of Brentwood that were of the type Aedes aegypti, which have also been detected in Antioch over the past three years, when they became known in California.
County officials launched a program in July to release male Aedes aegypti treated with bacteria that will produce sterile eggs when they mate with females.
Male mosquitoes do not bite, so there is no risk to humans, according to county health officials.
Female Aedes aegypti are aggressive biters of humans and can pester hosts more than other types of mosquitoes, even in small numbers.
They can also transmit potentially dangerous viruses such as Zika, dengue fever, yellow fever, and chikungunya.
That has made eradicating them a priority for the Contra Costa Mosquito and Vector Control District, which leads pest control efforts in the county.
Even small amounts of water can serve as breeding grounds for mosquitoes. Officials recommend regularly inspecting properties for standing water and dumping or draining any that is found.
The mosquitoes in Brentwood were found because of a call from a resident. District officials urged anyone who encounters biting insects to report them online or (925) 685-9301.
Copyright © 2026 Bay City News, Inc. All rights reserved. Republication, rebroadcast or redistribution without the express written consent of Bay City News, Inc. is prohibited. Bay City News is a 24/7 news service covering the greater Bay Area.
Sign up for free local newsletters and alerts for the
Concord Patch
Patch.com is the nationwide leader in hyperlocal news.
Visit Patch.com to find your town today.