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Dengue Fever

Mosquito biting skin

What is dengue fever?

Dengue fever is a mosquito-borne viral infection that can cause severe flu-like illness and, occasionally, Dengue hemorrhagic fever, which can be fatal. The incidence of Dengue fever has increased 30-fold in the past fifty years and more than 400 million people are infected with the virus every year.

What causes dengue fever?

Dengue fever is caused by the Dengue virus, of which there are four main types: Dengue virus 1,2,3, and 4. Infection with one type of dengue virus does not confer immunity against the other types.

Dengue viruses are spread from person-to-person through the bite of an infected Aedes species mosquito (either Aedes aegypti or Aedes albopictus). These mosquitos are also responsible for spreading other diseases, such as chikungunya and Zika.

Signs and symptoms of Dengue fever appear, on average, five to eight days after being bitten by an infected mosquito.

What are the symptoms of dengue fever?

Symptoms of Dengue fever can range from a mild, flu-like illness to severe, Dengue hemorrhagic fever.

Initial symptoms may vary but can include:

  • High fever (105°F [40.5°C])
  • Headache
  • Eye pain
  • Facial flushing
  • Lower back pain
  • Muscle and joint pain
  • Nausea and vomiting
  • Red eyes
  • Swollen lymph nodes
  • Severe fatigue
  • Severe weakness

After two to three days the high fever reduces, and significant sweating occurs. Two to five days after the fever starts, a flat, red rash may appear over most of the skin. The palms of the hands and soles of the feet also become swollen and turn bright red. A different type of rash, which resembles the measles, appears later on in the course of the disease.

While most people recover from Dengue fever, in some people the condition progresses to dengue hemorrhagic fever which is characterized by severe symptoms of dengue fever accompanied by bleeding from the gums, nose, bowel, and into the internal organs; bruising and blood spots under the skin; pneumonia and inflammation of the heart. Those who have previously suffered from Dengue fever and children under the age of 10 are most at risk. The condition is fatal in approximately 5 percent of individuals.

How is dengue fever diagnosed?

Symptoms of Dengue fever can easily be confused with other conditions such as influenza, Zika, measles, mumps, malaria, or typhoid fever.

A doctor will ask you about your symptoms and your travel history, perform a physical examination, and order blood tests. Dengue fever usually presents with the characteristic combination of fever, rash, and headache (known as the Dengue triad) and that may help with the diagnosis.

What is the treatment for dengue fever?

Because Dengue fever is caused by a virus, there is no specific treatment apart from supportive measures (such as ensuring an adequate fluid intake including IV fluids if needed). Most people fully recover from the condition although fatigue and weakness may last for several weeks.

Other treatments may include:

  • Acetaminophen (do not take aspirin or ibuprofen)
  • Blood transfusions

How can dengue fever be prevented?

Although a Dengue fever vaccine is available in some parts of the world, effectiveness varies among the different serotypes and there is a risk of people developing severe Dengue if they are exposed to Dengue after being vaccinated (and have not previously had Dengue fever before).

People traveling to areas at risk of dengue fever should:

  • Protect themselves from mosquito bites during the day and night
  • Use an EPA-registered insect repellent that protects against disease-carrying mosquitos, such as DEET, picaridin, Oil of Lemon Eucalyptus, IR3535, PMD, or 2-undecanone, on all exposed areas of skin (some of these may not be suitable for children under the age of 3)
  • Wear clothing and hats that cover the arms, legs, and head and use a bed net at night
  • Stay in accommodation that has screens on the doors and windows

Not everybody who gets infected with Dengue gets symptoms, but symptomless Dengue-infected people are at risk of passing the infection onto others if they get bitten by a mosquito and then that mosquito bites somebody else. Even if a person does not feel unwell, they should take measures to protect themselves from mosquito bites (so they don’t inadvertently pass on the disease to others) for 3 weeks after returning from a high-risk Dengue area.