Public Health Investigating Fifth Case of Locally Acquired Dengue

The Los Angeles County Department of Public Health is investigating a new case of locally acquired dengue in a resident of El Monte. The person had no history of travel to areas where dengue is endemic. This case of local transmission does not appear to be related to the cases previously reported by Public Health and is the fifth case of locally acquired dengue reported in LA County this year. LA County is seeing an emergence of locally acquired dengue that is extremely rare for a region where the virus has not previously been transmitted by mosquitoes.

“This case further indicates that dengue can spread in our community. Preventing mosquito bites and mosquito breeding is the best way stop local transmission of dengue,” said Muntu Davis, MD, MPH, Los Angeles County Health Officer. “Mosquitos thrive in hot weather, increasing the risk of bites and mosquito-borne diseases. People should follow these simple steps to reduce their exposure to mosquitoes and risk for mosquito bites: 1) Use insect repellent on you and your family; 2) Remove items that hold standing water around your home where mosquitoes can lay eggs and breed; and 3) Use, install, or repair window and door screens to prevent mosquitoes from entering your home."

It can take 4-7 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.

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.

Public Health continues to work closely with the San Gabriel Valley Vector Control District on enhanced surveillance and active engagement with the community. Outreach teams are visiting residents in the neighborhood where this case was identified to provide information on dengue and encourage residents to take protective measures against mosquitoes. The San Gabriel Valley 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.

"The San Gabriel Valley Mosquito and Vector Control District is committed to protecting residents through enhanced mosquito control measures and active public outreach," said SGVMVCD District Manager Jason Farned. "We are intensifying our efforts with targeted backpack and truck-mounted treatments, increased surveillance, and ongoing inspections to reduce adult mosquitoes in the community. Residents play a critical role in this fight by eliminating standing water on their properties and protecting themselves with EPA-approved repellents.”

Everyone in LA County can take proactive steps to reduce mosquito breeding, avoid mosquito bites, and prevent the ongoing local transmission of dengue. This includes:

· Wearing 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.

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

· Preventing mosquito breeding: Eliminate standing water where mosquitoes can lay eggs.

o 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.

o 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.

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

o Throw away old items in your patio or yard that can hold water, e.g., old car tires and children’s toys.

o Call 2-1-1 or your local vector control agency to report persistent problems to your mosquito control district

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 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

· 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.

For more information, visit: publichealth.lacounty.gov/acd/VectorDengue.htm

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.

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