Symptoms and causes

Symptoms

Many people, especially children and teens, may experience no signs or symptoms during a mild case of dengue fever. When symptoms do occur, they usually begin four to seven days after you are bitten by an infected mosquito.

Dengue fever causes a high fever — 104 F degrees — and at least two of the following symptoms:

  • Headache
  • Muscle, bone and joint pain
  • Nausea
  • Vomiting
  • Pain behind the eyes
  • Swollen glands
  • Rash

Most people recover within a week or so. In some cases, symptoms worsen and can become life-threatening. Blood vessels often become damaged and leaky. And the number of clot-forming cells (platelets) in your bloodstream drops. This can cause a severe form of dengue fever, called dengue hemorrhagic fever, severe dengue or dengue shock syndrome.

Signs and symptoms of dengue hemorrhagic fever or severe dengue — a life-threatening emergency — include:

  • Severe abdominal pain
  • Persistent vomiting
  • Bleeding from your gums or nose
  • Blood in your urine, stools or vomit
  • Bleeding under the skin, which might look like bruising
  • Difficult or rapid breathing
  • Cold or clammy skin (shock)
  • Fatigue
  • Irritability or restlessness

When to see a doctor

Call 911 or go to the nearest emergency room if you've recently visited a region in which dengue fever is known to occur and you develop emergency symptoms, such as severe abdominal pain, vomiting, difficulty breathing, or blood in your nose, gums, vomit or stools.

If you develop a fever and milder symptoms common to dengue fever, call your doctor.

Causes

Dengue fever is caused by any one of four types of dengue viruses spread by mosquitoes that thrive in and near human lodgings. When a mosquito bites a person infected with a dengue virus, the virus enters the mosquito. When the infected mosquito then bites another person, the virus enters that person's bloodstream.

After you've recovered from dengue fever, you have immunity to the type of virus that infected you — but not to the other three dengue fever virus types. The risk of developing severe dengue fever, also known as dengue hemorrhagic fever, actually increases if you're infected a second, third or fourth time.

Risk factors

Factors that put you at greater risk of developing dengue fever or a more severe form of the disease include:

  • Living or traveling in tropical areas. Being in tropical and subtropical areas increases your risk of exposure to the virus that causes dengue fever. Especially high-risk areas are Southeast Asia, the western Pacific islands, Latin America and the Caribbean.
  • Prior infection with a dengue fever virus. Previous infection with a dengue fever virus increases your risk of having severe symptoms if you're infected again.

Complications

If severe, dengue fever can damage the lungs, liver or heart. Blood pressure can drop to dangerous levels, causing shock and, in some cases, death.