HealthSheets™


Understanding Dengue Fever

Dengue (DEN-gee or DEN-gay) is a viral illness that is spread by mosquitoes. It is also called dengue fever. There are mild and moderate to severe forms of dengue. The mild form is most common. The severe form is called dengue hemorrhagic fever (DHF). Without treatment, DHF may cause death. 

What causes dengue?

Aedes mosquito
Aedes mosquito

The virus is spread by Aedes mosquitoes. You can get the virus if you are bitten by an infected mosquito. The mosquitoes transmit the virus by biting a person with dengue and then biting another person. The mosquitos are present throughout the Western hemisphere. Dengue is uncommon in most of the U.S., except Puerto Rico. It is most common in Latin America, Southeast Asia, Africa, and the Pacific Islands.

Symptoms of dengue

Mild dengue infection may have few symptoms. Moderate to severe dengue has 3 phases: febrile, critical, and recovery.

Febrile phase

Symptoms of the febrile phase last 3 to 7 days and include:

  • Sudden high fever

  • Skin redness or red patches on the skin

  • Severe headache

  • Pain behind the eyes

  • Severe joint and muscle pain

  • Nausea

  • Vomiting

  • Easy bruising and bleeding

Critical phase

The critical phase usually lasts 2 to 3 days. During this time, body temperature may return to normal. Symptoms of the critical phase include:

  • Vomiting that won’t stop

  • Severe pain in the belly (abdomen)

  • Fluid in the chest and belly

  • Rapid breathing

  • Low blood pressure

  • Bleeding

 A person with severe dengue may have trouble breathing, severe bleeding, damage to organs, or dengue shock syndrome. This can be fatal, and is a medical emergency.

Recovery phase

During the recovery phase, there is overall improvement. There may also be a rash and itchy skin. There may be heart and lung problems.

Diagnosing and treating dengue

See your healthcare provider if you have a fever or other symptoms within 2 weeks of returning from travel to an area where dengue occurs. Tell your provider where and when you traveled. Your provider can diagnose dengue fever with a blood test to check for the virus or antibodies in your blood.

If you have dengue fever, your treatment will depend on how severe your illness is. Symptoms are most commonly treated with bed rest and fluids. You may be given acetaminophen to reduce fever and pain. Don’t take aspirin, ibuprofen, or naproxen, as they may increase your risk of bleeding.

Preventing dengue

There is no vaccine for dengue fever. The best protection is to prevent mosquito bites. If you are traveling to an area where dengue fever is a risk:

  • Use insect repellent that contains 20% to 30% DEET on your skin and clothing

  • Stay in indoor areas that have screens or air conditioning

  • Use spray insecticide outdoors

  • Put a mosquito net around your bed

When to seek medical care

Call your healthcare provider right away if you have:

  • Severe belly pain

  • Vomiting that won’t stop

  • Blood in your vomit

  • Red patches on your skin

  • Bleeding from your nose or gums

  • Black, sticky stools

  • Pale, cold skin

  • Trouble breathing

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