Officials warn of spread in Los Angeles

Los Angeles health officials have confirmed another case of the mosquito-borne dengue fever, bringing the total number of cases this year to four.

The latest case was confirmed in Panorama City, The Los Angeles County Department of Public Health said in an announcement last week. The patient had not traveled to areas where dengue fever is endemic, the department said.

County health officials have confirmed the following cases of dengue fever since fall 2023:

Calling the latest number of local transmissions “unprecedented in Los Angeles County,” Dr. Muntu Davis, the Los Angeles County Health Officer, said in a news release the best way to stop the illness from transmission is by limiting mosquito bites and mosquito breeding.

“Using insect repellent to prevent mosquito bites, eliminating items that hold standing water around your home where mosquitoes can breed, and using or fixing screens on your doors and windows to keep mosquitoes out of the home are simple steps everyone can take to significantly reduce the risk of mosquito-borne disease for both you and your neighbors,” Davis said about the illness in the release.

What’s causing this rise in cases?

The Los Angeles County Department of Public Health said the increase in dengue fever cases is not just happening in Los Angeles.

“Dengue cases are on the rise around the world,” the agency wrote in an email Wednesday evening, adding that the disease is commonly spread by a species called the Aedes mosquito.

They were first found in Los Angeles County in 2011 and now, they are in nearly all cities in the county.

“What we are seeing in LA County in 2024 is a reflection of increased global dengue transmission in a region with widespread Aedes mosquitoes and many travelers from areas where dengue continuously or frequently circulates,” the agency said.

Another factor at play may be rising temperatures, according to the department. These higher temperatures allow Aedes mosquitoes to thrive in areas they typically couldn’t before. The rising temperatures can also affect how quickly mosquitoes multiply, how soon they become infectious and their biting patterns.

“All these factors can contribute to more mosquitoes and increased risk of local dengue spread,” the department said.

What is dengue fever?

Dengue fever is a mosquito-borne illness that is typically prevalent in tropical and subtropical areas, according to the Mayo Clinic. The illness can cause high fever and flu-like symptoms.

Those who are infected with the fever may have severe headache, pain behind the eyes, joint and muscle pain, rash and mild bleeding, the public health department said in its news release.

According to the Mayo Clinic, the fever is caused by one of four types of dengue viruses but you cannot get it from simply being around an infected person. The illness is spread through mosquito bites, typically from mosquitoes in places where humans live.

“When a mosquito bites a person infected with a dengue virus, the virus enters the mosquito,” the Mayo Clinic said on its website. “Then, when the infected mosquito bites another person, the virus enters that person’s bloodstream and causes an infection.”

Once people have recovered from the fever, they are immune to the type of virus that infected them, usually on a long-term basis, the clinic said. Still, they can become infected again by one of the other three virus types. If people are infected for a second, third or fourth time, they may develop severe dengue fever.

Severe dengue can lead to shock, severe bleeding and severe organ impairment, the public health department said in its news release.

While there are no specific medicines used to treat dengue, there are some “supportive medicines to help with fever and pain,” the public health department said. 

One type of dengue vaccine is available for use in areas with risk of dengue in the United States

There is one vaccine available for use in areas with risk of dengue in the U.S., the Centers for Disease Control and Prevention says. But the CDC notes specific recommendations for who should and should not receive a dengue vaccine.

How can I protect myself from dengue fever?

The Los Angeles County Department of Public Health recommends the following precautions:

• Wear EPA-registered mosquito repellents containing DEET, picaridin, IR3535, 2-undecanone and oil of lemon eucalyptus. They last the longest and are most effective, and come in the form of sprays, wipes and lotions.
• Wear long-sleeved clothes and pants when outside.
• Make sure home doors and windows have tight-fitting screens to keep out mosquitoes.
• Repair or replace screens with tears or holes.
• Eliminate standing water where mosquitoes can reproduce.
• Get rid of standing water in flower pots, saucers, birdbaths and other outdoor containers. 
• Cover water storage containers such as buckets and rain barrels. If containers do not have a lid, use wire mesh with holes smaller than an adult mosquito.
• Clean swimming pools, spas and drain water from pool covers.
• Throw away old patio or yard items that can hold water, such as old car tires and children’s toys.
• Call 2-1-1 or your local vector control department to report persistent problems to your mosquito control district.

Steps health officials are taking to protect community members

The public health department is working with the Greater Los Angeles County Vector Control District to visit residents in the neighborhood where cases have been reported. There, representatives let residents know how they can protect themselves.

The Greater Los Angeles County Vector Control District has also upped its mosquito trapping to reduce the chance of dengue fever spreading.

Those with questions can call a nearby clinic or doctor or the Public Health InfoLine at 1-833-540-0473. The line is open daily from 8 a.m. to 8 p.m.

This story was updated to add new information.

Saleen Martin is a reporter on ‘s NOW team. She is from Norfolk, Virginia – the 757. Follow her on Twitter at @SaleenMartin or email her at sdmartin@.com.