The Mosquito and Vector Management District of Santa Barbara County Alerts Residents to Mosquito-Borne Dengue Virus Infections in Los Angeles County

LA Mosquito Population Testing Verifies Local Transmission from Infected Mosquitoes

The Mosquito and Vector Management District of Santa Barbara County wants to alert residents that several individuals in the Greater Los Angeles area have contracted Dengue, a virus spread by mosquitoes. In early November, the California Department of Public Health conducted testing of a mosquito population in the vicinity of one of the human infections and verified that the mosquitoes (Aedes aegypti) carried the virus, marking the first time mosquitoes collected in California have tested positive for the Dengue virus. In California, the vast majority of Dengue infections are detected in individuals who have traveled abroad to regions where Dengue is present. 

“We always recommend caution around mosquitoes due to their known ability to spread disease,” said Brian Cabrera, MVMD General Manager. “Now with the verification of local transmission of Dengue fever from mosquitoes to people in Los Angeles, the potential for spread of the disease is closer to home and a good reminder that local residents can take steps to protect themselves from mosquito-borne disease.” 

Residents are urged to take action to “Fight the Bite” by following the 3 Ds:

• Deet — Use Deet or other repellents approved by the Environmental Protection Agency;

• Dawn or Dusk — Avoid being outside at these times when the mosquitoes are most active;

• Drain – Empty all sources of stagnant water that mosquitoes will lay their eggs in including buckets, bird baths, clogged rain gutters, old tires, containers of all kinds, unused hot tubs, etc.

Dengue infections were confirmed from 2 households in the City of La Puente (San Gabriel Valley) while one was reported from North Hollywood and another from Sun Valley. So far in 2025, 145 cases of Dengue fever have been reported in California, all of them travel-related except for the six in Los Angeles county known to have been contracted from local mosquitoes. In 2024, 720 cases were reported across the state with 14 of them attributed to local transmission. 

Most people infected with Dengue virus are asymptomatic, but in rarer cases symptoms include severe fever, body and head aches, rash and even death. The disease does not spread between people.  

One case of Dengue virus has been reported in Santa Barbara County in 2025, and five were reported in 2024. These cases were not from local transmission, meaning the infections were acquired while traveling outside of California. 

Wearing long-sleeved shirts and long pants can also provide protection from mosquitoes. Larger sources where mosquitoes are breeding, such as neglected swimming pools or stagnant water in creek beds and washes, for example, can be reported to the District at (805) 969-5050.