Dengue fever is a common mosquito-borne illness in many tropical and subtropical countries. One study estimated that 50 million infections occur every year. Symptoms can be mild and include:

  • fever
  • rash
  • muscle and joint pain

Mosquitoes become infected with the dengue virus when they bite people with infected blood and then spread it when they bite another person. Most cases of dengue fever happen when a mosquito bites someone, but people can get the virus if they’re exposed to infected blood.

Dengue fever rarely causes death. However, the infection can progress into a more serious condition known as severe dengue or dengue hemorrhagic fever.

Symptoms of dengue hemorrhagic fever include:

  • bleeding under the skin
  • frequent vomiting
  • abdominal pain

The more severe symptoms of dengue hemorrhagic fever often develop after the person starts to recover from the dengue virus infection.

Dengue hemorrhagic fever can occur when someone is bitten by an infected mosquito or exposed to infected blood. Mosquitoes are the most common cause.

There are four different types of the dengue virus. Once you contract one of the viruses, you develop immunity to that virus for the rest of your life.

However, this immunity won’t protect you from the other viruses. It’s possible to contract all four different types of the dengue virus in your lifetime.

In fact, being exposed to one type of dengue virus predisposes you to severe dengue when you’re exposed to a different one. In other words, repeated exposure to the dengue virus can make it more likely that you’ll develop dengue hemorrhagic fever.

Living in or traveling in Southeast Asia, South and Central America, sub-Saharan Africa, and parts of the Caribbean can increase your chance of contracting the dengue virus. Other people at higher risk include:

  • infants and small children
  • pregnant people (the virus may be passed to the fetus)
  • older adults
  • those with compromised immune systems

Symptoms of the dengue virus generally include:

  • mild, moderate, or high fever
  • headaches
  • nausea
  • vomiting
  • pain in the muscles, bones, or joints
  • rashes on the skin

You may feel like you’re recovering from dengue fever and then suddenly develop new and severe symptoms. These could be symptoms of dengue hemorrhagic fever. Call your doctor if you begin to experience:

  • restlessness
  • acute, or sudden, fever
  • severe abdominal pain
  • bleeding or bruising under the skin
  • cold or clammy skin
  • nosebleeds
  • steep decrease in blood pressure (shock)

Doctors will usually diagnose the type of dengue virus and then begin to look for signs of dengue hemorrhagic fever. Your doctor may do the following:

In addition to performing these tests, your doctor may ask you questions about your personal and family medical history. They may ask about your lifestyle and recent travels, and they’ll try to rule out other conditions, like malaria, that are common in tropical regions.

The goal of treatment is to manage symptoms and keep the infection from becoming more severe. Severe cases may need emergency treatments such as:

  • over-the-counter or prescription drugs to manage pain
  • electrolyte therapy
  • blood transfusions
  • careful monitoring of blood pressure
  • oxygen therapy
  • skilled nursing observation

You may receive hydration through an IV. However, in the case of severe dengue, too much IV fluid can lead to “third spacing,” where the fluids leak out of blood vessels.

All of these methods are aimed at controlling and alleviating your symptoms while helping your body heal naturally. Doctors will continue to monitor your body’s response. Severe dengue fever is often more difficult to treat because the symptoms are worse and appear at a faster rate.

Complications from severe or acute dengue hemorrhagic fever may include:

  • seizures
  • brain damage
  • blood clots
  • damage to the liver and lungs
  • heart damage
  • shock
  • death

Prompt treatment can help prevent complications, but there are no antiviral drugs for dengue virus infection.

The outlook for dengue hemorrhagic fever depends on how early the condition is detected. People who receive care in the early stages of dengue infection will often recover. According to the Centers for Disease Control and Prevention (CDC), this usually happens within a week.

Dengue fever isn’t common in the United States, but travelers to areas of dengue epidemics can be at a high risk for infection. It’s important to talk to your doctor about any international travel plans and to be aware of any diseases common in your destination.

The CDC keeps an up-to-date health map to show areas that have recent reports of dengue infection. Call a doctor right away if you become ill with any dengue symptoms.

Researchers are working on a vaccine to prevent dengue fever. However, it’s currently unavailable.

The best way to prevent dengue fever is to protect yourself from being bitten by mosquitos. Wear clothing that covers your arms and legs, and use mosquito netting and mosquito repellent when traveling in the tropics.