Dengue Fever

Overview

Dengue fever is an infectious disease carried by mosquitoes and caused by any of four related dengue viruses.

The disease poses a major global health threat. Almost half of the world’s population, approximately 4 billion people, live in areas with a risk of dengue. Dengue is often a leading cause of illness in areas where it is endemic.

The geographical distribution of dengue viruses overlaps with other mosquito-borne viruses, including Zika virus, yellow fever virus, and chikungunya virus, as well as mosquito-borne diseases like malaria.

In the United States, limited transmission occurs periodically in states with hot climates where Aedes aegypti and Aedes albopictus mosquitoes are present.

Signs and Symptoms

Dengue fever can range from mild fever to severe hemorrhagic fever. The disease used to be called “break-bone” fever because it sometimes causes severe joint and muscle pain that feels like bones are breaking.

Mild symptoms of dengue can be confused with other illnesses that cause mild fever, with or without a rash.

Warning signs of more severe disease usually appear around the time when fever breaks and includes:

• Belly pain or tenderness
• Clinical fluid accumulation
• Liver enlargement
• Persistent vomiting
• Bleeding from the nose or gums
• Feeling tired, restless, or irritable

Anyone experiencing these warning signs should seek medical care immediately, as severe dengue can progress rapidly.

Related Health Effects

Dengue fever can progress quickly. Warning signs of severe disease appear as the fever reduces, and the virus decreases in the blood. The risk of severe disease increases with a second dengue infection and decreases with subsequent infections.

Causes and Risk Factors

Dengue fever is caused by bites from Aedes aegypti and Aedes albopictus mosquitoes infected with any of four related dengue viruses.

Key risk factors for dengue include:

• Living in or traveling to the belt, including Central and South America, Africa, South-East Asia, and Pacific Islands
• Exposure to Aedes aegypti or Aedes albopictus mosquitoes, which can carry the dengue virus
• Living in or traveling to states in the United States where these mosquitoes are present

Prevention Guidance

Steps to reduce the risk of mosquito bites include:

• Wear protective clothing.
• Sleep in a screened or air-conditioned room with windows closed.
• Use a bed net outdoors to avoid getting bitten.
• Use an insect repellent that is at least 20 percent DEET, as recommended by the Centers for Disease Control and Prevention (CDC), to ward off mosquitoes and other bugs.

Though repellents such as oil of lemon eucalyptus (OLE) or para-menthane-diol (PMD) and insect repellents made from plants, including citronella products, may protect against mosquitoes, they work for less time than products containing DEET.

There are several dengue vaccines that are approved for use in different countries. A multi-dose vaccine, Qdenga, protects against all four types of dengue viruses and was developed with extensive support from NIH. Qdenga is approved in more than 40 countries for a range of ages.

Diagnosis

Dengue cases are detected year-round, with increases in incidence during the rainy season in endemic countries. Epidemics (large-scale outbreaks) typically occur on 3–5-year cycles.

Quick and effective diagnosis of dengue is critical to controlling outbreaks, treating the disease, and reducing mortality. See a healthcare provider for testing if you think you have dengue fever.

To diagnose dengue, a provide may use:

• An NS1 antigen test to detect the virus in the blood during the first few days of infection.
• Nucleic acid amplification test (NAAT/PCR), which is the same test used to diagnose viruses like COVID and other Coronaviruses, may also be used. This is the preferred diagnostic method for dengue fever though it is limited by the level of virus in the blood.
• Serological methods such as ELISA or ICT (immunochromatographic test) which detect anti-dengue antibodies. IgG antibodies typically appear about one to two weeks after IgM and can persist for years, while IgM antibodies fade after a few months. This difference is useful when determining how recently someone was infected.

Serological tests can also show cross-reactivity with related flaviviruses, like Zika virus. Diagnostic testing is widely available in at-risk areas, but results may take several days, which can limit the treatment window.

Treatment and Management

Currently, there are no approved antiviral treatment for dengue, and recommended treatment is supportive and based on symptoms.

If you think you have dengue:

• See a healthcare provider if you develop a fever or have symptoms of dengue. Tell them about any recent travel.
• Rest as much as possible.
• Take acetaminophen (also known as paracetamol outside of the US) to control fever and relieve pain.
• Do not take aspirin or ibuprofen because these can increase the risk of bleeding.
• Drink plenty of fluids to stay hydrated. Drink water or drinks with added electrolytes.
• For mild symptoms, care for a sick infant, child, or family member at home.

Find Clinical Trials

Clinical trials uncover better ways to prevent, diagnose, treat, and understand diseases and conditions. To ensure results apply to everyone, volunteers of all ages, sexes, and backgrounds, including both healthy individuals and those with specific medical conditions, are needed. Find clinical trials on dengue fever.

Research Information

The National Institutes of Health (NIH) is the largest public funder of biomedical research in the world. NIH invests most of its budget in medical research seeking to enhance life and to reduce illness and disability. NIH-funded research has led to breakthroughs and new treatments helping people live longer, healthier lives, and building the research foundation that drives discovery.  

NIH-supported investigators are pursuing several approaches to treat dengue infection, including the discovery and development of novel antivirals. Some scientists are working to identify cellular and viral proteins to use as targets for drug intervention. In other studies, researchers are generating and evaluating neutralizing monoclonal antibodies and small molecule drugs in animal models, with results that may lead to new treatment options for people with dengue.

Biology and Transmission

NIH supports basic research activities aimed at better understanding the biology of the dengue virus, the progression of disease in infected people, and the interactions between the virus and the immune system. New research findings are shedding light on the mechanisms of dengue infection, such as how the virus enters cells and how the human immune system responds.

NIH-supported researchers studying the mosquito vector are also exploring interactions between the virus and vector, and how transmission is affected by mosquito immunity, genetics, and metabolic pathways.

Genomic Resources

NIH-funded genomic and bioinformatics resources offer scientists new tools to support the discovery of vaccines, drugs, and diagnostics. The entire genome sequence of the Aedes aegypti mosquito, the main carrier of dengue virus, has been decoded. This information may help investigators identify the mosquito proteins essential to dengue replication and transmission. NIH also provides genetic sequence data from more than 50,000 viral strains isolated from people with dengue, which may help researchers identify viral sequences associated with disease severity.

Treatment 

NIH-supported investigators are pursuing several approaches to treat dengue infection, including the discovery and development of novel antivirals. Some scientists are working to identify cellular viral proteins to use as targets for drug intervention. In other studies, researchers are generating and evaluating neutralizing monoclonal antibodies and small molecule drugs in animal models, with results that may lead to new treatment options for people with
dengue.

Vaccines

NIH supported the development of Qdenga, a live-attenuated vaccine that is approved in over 40 countries (it is unavailable in the U.S.). Other NIH-funded investigators are working to develop dengue vaccines using different live-attenuated dengue viruses, recombinant proteins, viral vectors, and DNA.

Mosquito Control

NIH-supported researchers are exploring ways to prevent mosquitoes from transmitting dengue viruses. For example, a current approach uses Wolbachia bacteria to eliminate the virus within the mosquito.

Other research areas currently supported by NIH include understanding how mosquitoes identify human hosts and the development of novel traps and repellents.

Find NIH-funded research projects using NIH RePORTER, a searchable database of current and past research projects supported by NIH and other federal agencies.