Southern California is currently seeing an increase in locally acquired dengue cases. In 2024, Los Angeles and San Diego County Public Health reported nine human cases of this nature. Typically, most dengue cases in California are travel-related, contracted from mosquitoes abroad. As of now, Riverside County has not reported any locally acquired dengue cases.
The Aedes aegypti mosquito, which transmits dengue, is now prevalent in Southern California. This species is small and black and white, known for its aggressive daytime biting behavior focused on humans. Residents are advised to eliminate standing water around their homes to reduce the mosquito population. "With fall temperatures, we often spend more time outdoors. This mosquito is also active in the fall months, making it more likely people will be bitten. Wearing repellent is essential to staying healthy," said Jeremy Wittie, General Manager for the Coachella Valley Mosquito and Vector Control District.
Travel-related dengue cases have risen due to ongoing global outbreaks. In March 2024, Puerto Rico declared a dengue outbreak. The U.S. Centers for Disease Control and Prevention issued a health alert advisory regarding increased risks of dengue virus infections within the United States this year.
Dengue fever results from infection by one of four related viruses spread through bites from infected Aedes mosquitoes. Symptoms include fever with aches and pains such as eye pain (typically behind the eyes), muscle pain, joint or bone pain, nausea, vomiting, and rash.
Residents can help reduce mosquito populations by dumping standing water where mosquitoes breed—like potted plant saucers—and using insect repellents with EPA-registered ingredients like DEET or picaridin. Ensuring window and door screens are intact can also prevent mosquitoes from entering homes.
If experiencing symptoms related to dengue fever, individuals should contact their primary care doctor.