LA Sees Unprecedented Cluster of Locally Acquired Dengue Cases, Public Health Investigates

Public Health is investigating two additional cases of locally acquired dengue in residents of the City of Baldwin Park. These residents have no history of travel to areas where dengue is endemic prior to their symptoms. This now brings the total number of cases of locally acquired dengue in LA County in 2024 to three, which is an unprecedented number of locally transmitted cases for a region where dengue has not previously been transmitted by mosquitoes. Public Health initially reported a confirmed case of locally acquired dengue on Sept. 9.

Dengue is primarily transmitted through the bite of an infected Aedes mosquito. Although Aedes mosquitoes are common in LA County, cases of locally acquired dengue are extremely rare. Almost all previously reported dengue cases in LA County have been associated with travel to a country where dengue is commonly spread.

These additional cases of local virus transmission serve as a reminder for all Los Angeles County residents that simple steps to prevent mosquito breeding and mosquito bites can lower the risk of mosquito-borne diseases and prevent more sustained transmission in the future.

Dengue fever can cause flu-like symptoms including high fever, severe headache, pain behind the eyes, joint and muscle pain, rash, and mild bleeding. Severe cases can result in shock, severe bleeding and severe organ impairment which require immediate medical attention.

Symptoms of dengue may mimic other viruses so healthcare providers should be vigilant for dengue fever in patients with acute febrile illness and test for and report suspect cases of mosquito-borne diseases. 

Public Health is working with local vector control agencies, the City of Baldwin Park and Public Health outreach teams to provide door-to-door information on dengue risk and mosquito bite prevention and control measures in the local area. The San Gabriel Valley Mosquito and Vector Control District has increased mosquito trapping for identification and testing and abatement operations to reduce the risk of additional spread in the affected neighborhood.

Mosquitoes breed in standing water and everyone is urged to follow these simple steps: Tip, Toss, and Protect:

• Tip out standing water at least every week. Even a small amount, like in a bottle cap, can become a breeding ground for mosquitoes.
• Toss any unused containers that can collect water.
• Protect yourself from mosquito bites by using repellents containing EPA-approved active ingredients, such as DEET, Picaridin, IR3535, or oil of lemon eucalyptus.

Cases of locally acquired dengue were previously confirmed by Long Beach and Pasadena in fall 2023.

Dengue is a disease caused by a virus that spreads through the bite of an infected mosquito. 

Symptoms of dengue typically last two to seven days. Most people will recover after about a week. About one in twenty people with dengue can develop severe disease which can be life threatening.

The most common symptoms of dengue are fever and one or more of the following:

• Eye pain
• Headache
• Muscle, bone or joint pain
• Nausea or vomiting
• Rash

There are no specific medicines to treat dengue. There are supportive medicines to help with fever and pain. There is a vaccine for dengue, but it is NOT approved for use in U.S. travelers who are visiting but not living in an area where dengue is common.

Details: publichealth.lacounty.gov/acd/VectorDengue.htm  and 1-833-540-0473, daily, 8 a.m. to 8 p.m.