Dengue fever is a viral infection. It can range from mild to severe and life-threatening,


An infected mosquito passes the virus through a bite to the skin. The virus enters the blood. It spreads throughout the body.

Mosquito Bite
Mosquito bite

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Risk Factors

The risk for dengue fever higher for those who live in or travel to:

  • Southeast Asia
  • Western Pacific
  • Americas
  • Eastern Mediterranean
  • Africa


Some people do not have symptoms. Others may have a mild, flu-like illness. Symptoms may be:

  • Fever and chills
  • Headache or eye pain
  • Muscle or bone pain
  • Red or purple spots in skin
  • Minor bleeding in the nose or gums
  • Nausea or vomiting

Serious signs are:

  • Severe belly pain
  • Frequent vomiting
  • Bleeding from the gums or nose that is hard to stop
  • Black tarry stools or blood in the urine
  • Tiredness or restlessness
  • Problems breathing
  • Pale, cold, or clammy skin
  • Feeling faint

A serious infection can lead to shock and organ failure.


The doctor will ask about your symptoms, and health and travel history. A physical exam and blood tests may be done.

A tourniquet test may be done to check for bleeding under the skin. This test uses an inflated blood pressure cuff on the upper arm for 5 minutes.


Treatment depends on how severe the illness is. It may include rest and replacing fluids by mouth or IV.

In severe cases, a blood transfusion may be given.


The risk of infection may be reduced by mosquito control measures. A dengue vaccine is available in some countries.


Centers for Disease Control and Prevention

IDSA—Infectious Diseases Society of America


Public Health Agency of Canada

Travel Health and Safety


Dengue. Centers for Disease Control and Prevention website. Available at: Accessed February 1, 2021.

Dengue. EBSCO DynaMed website. Available at: Accessed February 1, 2021.

Dengue fever. National Institute of Allergy and Infectious Diseases website. Available at: . Accessed February 1, 2021.

Karesh J, Mazzoli R, et al. Ocular manifestations of mosquito-transmitted diseases. Military Medicine, 2018; 183 (S): 450-458.

Mosquito avoidance. EBSCO DynaMed website. Available at: Accessed February 1, 2021.

Last reviewed September 2021 by David L. Horn, MD, FACP  Last Updated: 2/1/2021