First Locally Acquired Dengue Case Prompts Public Health Investigation

The Los Angeles County Department of Public Health is investigating the first case of locally acquired dengue for the 2025 mosquito season in a resident of the San Gabriel Valley. The person reported no history of travel to areas where dengue is endemic. The individual developed symptoms in late September and is recovering. While the potential risk for widespread dengue virus transmission in Los Angeles County remains low, this case highlights the presence of infected mosquitoes locally and underscores the importance of preventive measures to control the spread of this virus.

Dengue is transmitted primarily through the bite of infected Aedes mosquitoes. It can take 5-7 days for a person to develop symptoms after being bitten by a mosquito infected with dengue. Persons infected with dengue may have flu-like symptoms including high fever, severe headache, pain behind the eyes, joint and muscle pain, rash, and mild bleeding. Severe dengue can result in shock, severe bleeding and severe organ impairment which require immediate medical attention. Residents who have symptoms of dengue should see their healthcare provider. A blood test is the only way to confirm dengue infection.

About Dengue

Dengue is a disease caused by a virus that spreads through the bite of an infected mosquito. Dengue is common in tropical and subtropical regions such as the Caribbean (including Puerto Rico), Central and South America, Southeast Asia, and the Pacific islands. Because the types of mosquitoes that spread dengue are common throughout many areas of the United States, local spread of dengue can occur. However, dengue is not commonly spread by mosquitoes in LA County. Most cases in LA County have been identified among those who have traveled to areas where dengue commonly occurs.

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 and 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: ph.lacounty.gov/dengue

For questions or to find a nearby clinic or doctor, call the Public Health InfoLine at 1-833-540-0473, open every day from 8 a.m. to 8 p.m.