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 infected people, and then spread it when they bite another person. Most cases of the dengue virus are caused when a mosquito bites someone, but you can get the virus if you are exposed to infected blood.

Dengue virus 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 you start to recover from the dengue virus.

Dengue hemorrhagic fever can occur when someone is bitten by a mosquito or exposed to blood infected with the dengue virus. Infected mosquitoes are the most common causes.

There are four different types of the dengue virus. Once you are infected with one of the viruses, you develop immunity to that virus for the rest of your life. However, this immunity will not protect you from the other viruses. It is possible to be infected with all four different types of the dengue virus in your lifetime.

Repeated exposure to the dengue virus can make it more likely that you will develop dengue hemorrhagic fever.

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

  • infants and small children
  • pregnant women (the virus may be passed from mother to 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 are 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
  • large 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:

  • check your blood pressure
  • examine your skin, eyes, and glands
  • perform blood tests and coagulation studies
  • take a chest X-ray

In addition to performing these tests, your doctor may ask you questions about your personal and family medical history. Your doctor may ask about your lifestyle and recent travels. They may also 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:

  • hydration with intravenous (IV) fluids
  • over-the-counter or prescription drugs to manage pain
  • electrolyte therapy
  • blood transfusions
  • careful monitoring of blood pressure
  • oxygen therapy
  • skilled nursing observation

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.

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 Mayo Clinic, this usually happens within a week.

Dengue fever is not common in the United States, but travelers to areas of dengue epidemics can be at a high risk of infection. It’s important to talk to your doctor about any international travel plans, and to be aware of any diseases in the area you’re traveling to. 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 is 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. Use mosquito netting and mosquito repellent when traveling in the tropics.