Dengue is is caused by the dengue virus, transmitted by mosquitoes. The disease is widespread in tropical and sub-tropical regions (South America, Caribbean, Asia, Africa and Australia). The dengue virus is transmitted by the mosquito that also transmits yellow fever (Aedes aegypti) and by the tiger mosquito (Aedes albopictus). The number of infections worldwide has rapidly increased over the past decades, especially in urban areas on account of the tiger mosquito having adapted well to this environment. With the tiger mosquito now established in southern Europe, small outbreaks of dengue occur there with greater frequency (e.g. in France). In Belgium, only imported cases are diagnosed in travellers from regions where the virus circulates.

What is dengue?

  • Dengue is caused by the dengue virus, of which there are four serotypes (DENV-1, DENV-2, DENV-3 and DENV-4).
  • The dengue virus is transmitted by the mosquito that also transmits yellow fever (Aedes aegypti) and by the tiger mosquito (Aedes albopictus). People can also become infected through blood transfusions or transplants.
  • A pregnant woman infected with dengue can also transmit the infection to her child during pregnancy or childbirth.


  • Around 1 in 4 people infected with dengue virus develop symptoms after an incubation period of 3 to 14 days. 
  • In the case of so-called ‘classic’ dengue fever, the following symptoms may appear: 
    • sudden high fever (up to 41°C)
    • headaches (usually behind the eyes)
    • muscle and joint pain
    • skin rash
    • nausea 
    • vomiting
    • cough and sore throat. 
  • People with this mild form recover after a few days to a week.
  • A minority (<5%) of those infected have a severe form of dengue (formerly known as dengue haemorrhagic fever). Without proper treatment, this severe form can be fatal.
  • Infection with one serotype results in immunity to that specific serotype, but not to other serotypes. People can therefore be infected with different dengue virus serotypes and become ill repeatedly. We speak of primary dengue when a person is infected with the virus for the first time and of secondary dengue when a person is reinfected with a different serotype. The risk of developing a severe form of dengue appears to be greater with secondary dengue than with primary dengue

Diagnosis, treatment and prevention

  • If the doctor suspects dengue fever, the diagnosis can be made by way of a blood test. Depending on the stage of the disease, different tests can be used, such as a PCR test, antigen test or serology.
  • There is no specific treatment for dengue. Treatment is symptomatic, with painkillers and rehydration in the case of fever. Aspirin and anti-inflammatories should be avoided because they increase the risk of bleeding. In the case of severe forms, medical attention should be sought as a matter of urgency.
  • Prevention is done by avoiding mosquito bites.
  • A vaccine for use in individuals four years of age and older (QDENGA) has been approved in Europe end of 2022, which provides protection against fever and hospitalisation resulting from dengue disease caused by any of the four dengue virus serotypes. The vaccine is expected to be soon available in Belgium. 

Sciensano is responsible for the epidemiological surveillance of dengue in humans in Belgium, as well as for the monitoring of exotic mosquitoes of the Aedes genus (through the MEMO+ project).

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