Report on Pasadena Dengue Cases Issued by Centers for Disease Control and Prevention (CDC) as Locally Acquired Dengue Cases Rise

PASADENA, Calif.-- Pasadena Public Health Department (PPHD) has published a report in the Centers for Disease Control and Prevention (CDC) Morbidity and Mortality Weekly Report (MMWR), sharing findings from the 2023 investigation of California's first locally acquired dengue case.

In October 2023, PPHD identified the first locally acquired case of dengue in California in a Pasadena resident who did not travel outside the United States. In collaboration with the San Gabriel Valley Mosquito and Vector Control District (SGVMVCD), the Department took immediate action, increased surveillance, and deployed resources. Enhanced epidemiologic neighborhood investigations identified a second infection of dengue not associated with travel in a Pasadena resident who did not have symptoms.

"As a result of our investigation last year, PPHD found that dengue may be more prevalent in our region than expected," said Acting Director of Public Health, Manuel Carmona. "Recently identified dengue cases confirm our findings, demonstrating the importance of taking steps to prevent mosquito breeding in our community."

In the fall of 2023, the City of Long Beach reported a third dengue case. In 2024 thus far, Los Angeles County Department of Public Health identified nine cases of locally acquired dengue in the cities of Baldwin Park, El Monte, and Panorama City. An additional case in Escondido was also identified by the San Diego County Health and Human Services Agency.

The best way to prevent getting dengue is by avoiding mosquito bites. "Dengue has not been previously known to be transmitted locally by mosquitoes in our region," said Acting Health Officer, Dr. Parveen Kaur. "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, PPHD recommends residents and those who travel to areas where dengue is present:

• Wear insect repellent containing the approved active ingredients: DEET®, picaridin, IR3535, or oil of lemon eucalyptus
• Wear loosely fitted, light-colored, long-sleeved shirts, and long pants
• Repair holes in window screens to keep mosquitos outdoors

To reduce mosquito breeding, PPHD recommends residents:

• Eliminate standing water in buckets, saucers, toys, clogged rain gutters, discarded tires, and other items that hold 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
• Change the water in pet dishes, birdbaths, and troughs weekly

A person can be infected with the dengue virus from an infected Aedes mosquito, a type of mosquito that inhabits Pasadena. About one in four persons develop symptoms including fever, nausea, vomiting, rash, and body aches. Symptoms are typically mild and last two to seven days, but severe and even life-threatening illness can occur. There are no specific medicines to treat dengue. There is a vaccine for dengue, but it is not approved by the federal government for use by local residents or U.S. travelers who are visiting but not living in an area where dengue is common.

The San Gabriel Valley Mosquito and Vector Control District conducts routine mosquito control activities in the Pasadena region. To find your local vector district agency and for tips on mosquito prevention and approved mosquito repellents, visit SoCalMosquito.org. Additional information regarding dengue is available from the California Department of Public Health and the Centers for Disease Control and Prevention.