The Los Angeles County Department of Public Health, in collaboration with San Gabriel Valley Mosquito and Vector Control District, is investigating further local spread of dengue virus infection in Baldwin Park.

Two additional cases of locally acquired dengue have been identified, bringing the total to five cases concentrated in this area of the County. These new cases have no history of travel to areas where dengue is typically found.

This small local outbreak raises concern about the continued spread of dengue in Baldwin Park due to infected mosquitoes and the potential for spread to other areas of Los Angeles County as people travel throughout the County. It is essential for people living and working in Baldwin Park and other areas where a case of dengue has been identified to prioritize mosquito control and prevention measures to reduce the risk of spread.

Dengue spreads through the bite of infected Aedes mosquitoes, particularly Aedes aegypti and Aedes albopictus. Sustained spread of dengue in a neighborhood occurs when infected mosquitoes bite and spread dengue to people, who are then bitten by other mosquitoes. Those mosquitoes become infected and continue the cycle.

Aedes mosquitoes are most active during the daytime, with their peak biting (feeding) times generally being early in the morning (around dawn, just after sunrise) and late afternoon (just after sunset when the sky begins to darken).

Taking proactive measures and the cooperation of our community in these areas are vital for addressing this issue. Residents and businesses are strongly encouraged to take advantage of free vector control services including inspection and abatement of mosquito breeding sites at their homes. This is essential to helping identify and reduce the risk of further local spread of dengue.

“We are still investigating, but these new cases raise concern about the potential for continued local spread of dengue through the bite of infected mosquitoes in Baldwin Park. Many people infected may not show symptoms, making it challenging to detect and control the spread of the disease. However, with the help of the community, we can make a difference,” said Muntu Davis, MD, MPH, Los Angeles County Health Officer. “We need the support of everyone living and working in areas where mosquito-borne diseases are a concern. As part of this investigation, Public Health and San Gabriel Valley Mosquito and Vector Control District teams will conduct outreach and offer testing for dengue and enhanced mosquito control services for those living and working in the area. It’s also important for everyone to focus on protecting themselves from mosquito bites and eliminating places where mosquitoes can breed and grow. Together, we can protect our communities from dengue and other mosquito-borne diseases.”

Public Health urges healthcare providers to consider dengue in patients with acute febrile illness and test for and report suspect cases of mosquito-borne diseases. Providers should also routinely discuss mosquito bite prevention with patients and travelers.

About one in four people infected have symptoms of the infection, which can range from mild to severe. Symptoms of dengue may appear 2-7 days after being bitten by an infected mosquito. Persons infected with dengue may be asymptomatic or experience flu-like symptoms such as a fever, followed by severe headache, pain behind the eyes, joint and muscle pain, rash, and, possibly, mild bleeding. In severe cases, dengue can lead to severe bleeding and shock, a severe drop in blood pressure that can lead to organ failure, which requires immediate medical care. Residents experiencing symptoms should see their healthcare provider, as a blood test is needed to confirm dengue infection.

Public Health continues to work closely with vector control districts on enhanced surveillance and active engagement with the community to help with mosquito control. In Baldwin Park, outreach teams are visiting residents in the area where cases were identified to provide information on dengue, offer dengue testing, and encourage residents to take protective measures against mosquitoes. 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 area.

“As the situation evolves, the District is committed to maintaining an aggressive response strategy. We will continue aggressive mosquito control efforts, weekly surveillance testing, and public education to help protect public health and mitigate the risk of further transmission,” said SGVMVCD District Manager Jason Farned. “While dengue has not been detected in local mosquito populations, the district urges residents to take important measures to prevent mosquito bites.”

People living and businesses in the area under investigation can help detect and control the additional spread of disease by:

-Allowing Mosquito Inspections at your home or site: Please allow your vector control teams to inspect at your home or site for any mosquito breeding sites. This is crucial for our efforts to eliminate the risk of dengue fever spreading further.

-Allowing Collection Traps: If recommended, community members and businesses are encouraged to allow their vector control to set out mosquito collection traps to help identify and test for infected mosquito populations around their home or site.

Everyone in LA County must take proactive steps to prevent the ongoing local transmission of dengue. These simple measures include:

-Wear Mosquito Repellent: Mosquito repellents can keep mosquitoes prevent mosquito bites. EPA-registered repellents containing DEET, picaridin, IR3535, 2-undecanone, and oil of lemon eucalyptus are the longest lasting and most effective. They are available as sprays, wipes, and lotions. Consider wearing long-sleeved clothes and pants when outside.

-Keep mosquitoes out of your homes: Make sure that doors and windows have tight-fitting screens to keep out mosquitoes. Repair or replace screens with tears or holes.

-Prevent mosquito breeding:

-Eliminate standing water where mosquitoes can lay eggs.

-Clear standing water in flowerpots, saucers, birdbaths and other outdoor containers. Empty items that hold water inside and outside your home once a week. Mosquito eggs only need a thimbleful of water to hatch.

-Cover water storage containers such as buckets and rain barrels. For containers with no lid, use wire mesh with holes smaller than an adult mosquito.

-Clean and maintain swimming pools, spas and drain water from pool covers.

-Throw away old items in your patio or yard that can hold water, e.g., old car tires and children’s toys. Call 2-1-1 or your local vector control agency to report persistent problems to your mosquito control district.

This year, there have now been eight cases of locally acquired dengue reported in LA County. Panorama City and El Monte have each seen one and two cases respectively suggesting the virus has infected the local mosquito population in those cities. So far, none of these people have developed severe disease.

-Public Health’s first confirmed case of locally acquired dengue was reported September 9, 2024. Cases of locally acquired dengue were previously confirmed by Long Beach and Pasadena in fall 2023.

About Dengue

Dengue is a viral infection that spreads from mosquitoes to people. It is common in tropical and subtropical regions, like the Caribbean (including Puerto Rico), Central and South America, Southeast Asia, and the Pacific islands. In the United States, the types of mosquitoes that spread dengue are found in many areas, which means local spread of dengue can happen. However, dengue is not commonly spread by mosquitoes in LA County. Most cases in LA County have been linked to travel to areas where dengue is more common.

About one in four people infected have symptoms of the infection, which can be mild or severe. Symptoms of dengue typically last two to seven days. Most will recover after about a week. About one in twenty people with symptoms can develop severe disease with severe bleeding, shock, trouble breathing, and organ damage, which can be life threatening.

The most common symptoms of dengue are fever and any of the following:

-Aches and pains (headache, eye pain, muscle ache or joint pain)Nausea or vomiting

-Rash

Warning signs that severe disease may develop include any of the following:

-Severe, constant stomach pain or pain when touching the stomach

-Vomiting a lot (3 times in 1 hour or 4 times in 6 hours)

-Bleeding from the gums, nose, or vagina, or blood in urine

-Changes in how a person acts (like being very irritable or sleepy)

There are no antiviral medicines approved to treat dengue. Treatment is supportive and may require carefully managing fluid levels. 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.

For more information, visit the website.

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.