This year, the Centers for Disease Control and Prevention reported nearly 3,000 dengue fever cases in the US, a significant increase compared to previous years. These record numbers of dengue fever highlight a growing concern for both local and international outbreaks, specifically in Paris, which is set to experience an influx of millions for the 2024 Olympics, posing a serious risk of this event becoming a dengue fever super-spreader.
As of June 30, the CDC has issued a Level 1 Travel Notice, but current and future travelers, and even those staying local for the foreseeable future, must understand how to protect themselves effectively against dengue fever.
Also known as breakbone fever, dengue fever is a viral illness primarily spread by the Aedes aegypti mosquito, commonly known as the yellow fever mosquito. It's generally a short-lived infection, often lasting no more than two weeks, depending on the individual and the severity of their symptoms.
"Symptoms of dengue typically last two to seven days," Dr. Gabriela Paz-Bailey, chief of the CDC's Dengue Branch, told CNET.
Different forms of dengue include dengue fever -- of which there are four strains -- and dengue hemorrhagic fever, which presents severe symptoms beyond those typically associated with a dengue infection.
What causes dengue fever?
"[Dengue fever is] caused by one of the four different but related viruses: dengue 1, dengue 2, dengue 3, dengue 4," Paz-Bailey explained.
With four dengue virus strains, this means you can get dengue multiple times. While you may develop immunity to the first strain, you aren't protected from the others, and repeated infections increase the risk of developing a severe illness.
Dengue fever risk factors
The World Health Organization reported that between 100 and 400 million dengue infections are recorded each year. Since early 2023, more than 7,300 deaths have been reported globally.
Individuals at risk of contracting dengue fever include:
- Residents of tropical and subtropical regions: People living in these areas are at higher risk because they are frequently exposed to Aedes mosquitoes, since warm, humid climates provide ideal conditions for mosquito breeding.
- Travelers to endemic areas: Individuals visiting regions where dengue is common are at risk if they encounter infected mosquitoes.
Dengue is more common in certain US territories, such as Puerto Rico and the Virgin Islands, but it has been seen in increasing numbers within the states.
"Locally acquired dengue cases have been detected in Florida, Texas, Hawaii, Arizona and California," Paz-Bailey said. "Large outbreaks of dengue can increase the risk of dengue cases in US travelers. Because of the increased number of travel-associated cases and because the types of mosquitoes that spread dengue are present in some areas of the United States, small outbreaks might occur."
Dengue fever symptoms
According to the Mayo Clinic, dengue fever presents with a range of symptoms, including:
- High fever
- Severe headache
- Pain behind the eyes
- Joint and muscle pain
- Rash
- Vomiting
- Swollen glands
In worst cases, dengue hemorrhagic fever, or severe dengue, can develop, which presents potentially life-threatening symptoms.
"Severe dengue warning signs include belly pain or tenderness, vomiting (at least three times in 24 hours), bleeding from the nose or gums, vomiting blood or blood in the stool and feeling tired, restless or irritable," said Paz-Bailey.
When dengue fever symptoms appear
It is possible for an infected individual to show no signs or symptoms, but dengue fever symptoms typically begin four to 10 days after being bitten by an infected mosquito. Warning signs of severe dengue fever typically emerge within the first two days after the fever subsides.
When to see a doctor for dengue fever
A dengue diagnosis is important because it helps ensure prompt treatment, prevents serious health issues and supports efforts to control the spread of the virus.
"If a person thinks they have dengue, they should talk to their healthcare provider and let them know about recent travel," Paz-Bailey recommended.
Although mild dengue symptoms are usually not life-threatening, they can progress to severe dengue. If your condition worsens within the first few days after your fever subsides, even after seeing your primary care physician, seek urgent medical attention, as severe dengue can be fatal.
How is dengue fever diagnosed?
Early detection and diagnosis of dengue fever can significantly reduce the risk of severe complications and improve outcomes. The illness is diagnosed through a blood test, according to the Cleveland Clinic, and it's performed by a healthcare provider, who will draw a blood sample from a vein and send it to a laboratory to detect the presence of the dengue virus and which type you have. Because other viruses may present with similar symptoms, the blood test can also help determine if a different virus is causing the illness.
How is dengue fever treated?
No medical treatment or cure exists for dengue fever, according to WebMD. For now, the primary approach is to manage pain symptoms.
How to manage dengue fever symptoms
It's important to address each symptom appropriately. For the most part, you'll want to rest. Still, since common symptoms of dengue fever include high fever, severe headache, pain behind the eyes, joint and muscle pain, fatigue and a rash, you can lessen the discomfort of most symptoms with over-the-counter medications.
"Manage fever and relieve pain with acetaminophen. Do not take NSAIDs [nonsteroidal anti-inflammatory drugs], as they could increase bleeding," Paz-Bailey explained. To stay hydrated, she recommends fluids such as water, juice, milk or drinks with added electrolytes.
Your rash will fade once the fever subsides, but you'll want to keep the area clean, use calamine lotion or anti-itch creams and avoid scratching.
During this time, you'll also want to monitor symptoms closely so you can seek medical attention if you notice any new or worsening signs.
How to prevent dengue fever
Dengue vaccines, such as Dengvaxia, offer protection against dengue fever but are typically recommended only for individuals between 9 and 16 years old who have previously been infected with the virus and are living in an area where dengue is common. It is effective against all four types of the dengue virus, and it protects 80% of children who had dengue before vaccination from illness, hospitalizations and severe dengue.
Regardless of the vaccine's availability, you can avoid mosquito bites and reduce your risk of contracting dengue by taking these preventive measures against mosquito bites:
- Protective clothing: Wear long-sleeve shirts, long pants and socks to cover as much of your skin as possible. Also, avoid dark colors such as black or red, as color is one of many factors known to attract mosquitos.
- Mosquito nets: When outdoors, use mosquito nets, preferably treated with insect repellent, to create a barrier between you and mosquitoes.
- Windows and screens: Install window screens to keep mosquitoes out of your living spaces.
- Mosquito repellent: Apply mosquito repellents that contain DEET, Picaridin or IR3535 to exposed skin.
- Coils and vaporizers: Use mosquito coils and vaporizers to repel mosquitoes in indoor areas.
- Bug traps: Store-bought or DIY bug traps for mosquitoes -- such as those using sugar, dish soap and water to attract and trap them -- can be an effective and affordable method to reduce the chances of bites.
Combining these methods enhances your defense against dengue fever and can help reduce the risk of infection.