The U.S. Centers for Disease Control and Prevention has published a report detailing the Pasadena health officials’ investigation of California’s first locally acquired case of dengue, the city’s Public Health Department announced Thursday.
In October 2023, Pasadena health officials discovered a resident who had contracted locally acquired dengue, according to the report. The individual did not travel outside the United States.
In collaboration with the San Gabriel Valley Mosquito and Vector Control District, the health department increased mosquito surveillance and “enhanced epidemiologic neighborhood investigations” found a second dengue Pasadena resident infected with dengue who did not show symptoms of the viral illness, according to a statement from the Public Health Department.
“As a result of our investigation last year, PPHD found that dengue may be more prevalent in our region than expected,” Pasadena Acting Director of Public Health Manuel Carmona said in a statement. “Recently identified dengue cases confirm our findings, demonstrating the importance of taking steps to prevent mosquito breeding in our community.”
In the fall 2023, the city of Long Beach reported California’s third dengue case. So far this year, the Los Angeles County Department of Public Health identified nine cases of locally acquired dengue in Baldwin Park, El Monte and Panorama City. The San Diego County Health and Human Services Agency identified one case in Escondido.
The best way to prevent catching dengue is to avoid mosquito bites, officials said.
“Dengue has not been previously known to be transmitted locally by mosquitoes in our region,” Pasadena Acting Health Officer Dr. Parveen Kaur said in a statement. “The unprecedented number of locally acquired cases demonstrate the need for everyone to take precautions seriously. Basic precautions are effective at preventing all mosquito-borne illnesses, including dengue.”
To prevent mosquito bites, Pasadena Public Health recommended residents and anyone who travels to areas where dengue exists:
- wear insect repellent that has the approved active ingredients DEET, picaridin, IR3535 or oil of lemon eucalyptus;
- wear loose, light-colored, long-sleeved shirts and long pants; and
- fix holes in window screens to keep mosquitos outside.
To reduce mosquito the mosquito population, health officials suggested that residents:
- get rid of standing water in buckets, saucers, toys, clogged rain gutters, discarded tires and other items that contain water;
- cover rain barrels and screen all openings with fine mesh;
- filter and chlorinate swimming pools and spas and report neglected pools to the vector control district;
- use a pump to circulate water in fountains and ponds; and
- change the water in pet dishes, birdbaths and troughs at least once a week.
A person can be infected with the dengue virus via the bite of an infected Aedes mosquito, which inhabits Pasadena and many other parts of the U.S.
About one in four people develop symptoms that may include fever, nausea, vomiting, rash and body aches, officials said. Symptoms usually are mild, lasting two to seven days, but severe and possibly life-threatening illness is possible.
No medications specifically treat dengue, and the dengue vaccine is not approved by the federal government for U.S. residents or U.S. travelers visit but don’t live in an area where dengue is endemic.
The San Gabriel Valley Mosquito and Vector Control District regularly does mosquito-control operations in the Pasadena area. Links to local vector district agencies and tips on mosquito prevention and repellents are online at SoCalMosquito.org.