Infectious diseases transmitted by the tiger mosquito

Dengue

Dengue or "tropical flu" is caused by the dengue virus, of which there are four serotypes (DENV-1, DENV-2, DENV-3 et DENV-4).The disease is widespread in tropical and subtropical regions (South America, the Caribbean, Asia, Africa and Australia). The dengue virusis transmitted by the mosquito that also transmits yellow fever (Aedes aegypti) and by the tiger mosquito (Aedes albopictus). The number of infections worldwide has risen rapidly in recent decades, particularly in urban areas, as the tiger mosquito has adapted well to this environment. Now that the tiger mosquito is established in southern Europe, small-scale epidemics of dengue fever are occurring more frequently (in France, for example). In Belgium, only imported cases have been diagnosed in travellers from regions where the virus is circulating.

People can also be infected through blood transfusions or transplants. A pregnant woman infected with dengue fever can also transmit the infection to her child during pregnancy or childbirth.

What are the symptoms and complications ?

Around one in four people infected with the dengue virus develops symptoms after an incubation period Time between infection and appearance of symptoms. of 3 to 14 days. In the case of so-called "classic" dengue fever, symptoms such as sudden high fever (up to 41°C), headaches (usually behind the eyes), muscle and joint pain, a skin rash, nausea or vomiting may appear. A cough and sore throat may also occur. People with this mild form recover within a few days to a week.

A minority (<5%) of infected people have a severe form of dengue (previously known as dengue haemorrhagic fever). Without appropriate 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 serotypes of the dengue virus and fall ill several times. Primary dengue fever occurs when a person is infected with the virus for the first time, and secondary dengue fever occurs 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.

How is dengue diagnosed ?

If the doctor suspects dengue fever, the diagnosis can be made by a blood test. Depending on the stage of the disease, different tests may be used, such as PCR Acronym for polymerase chain reaction, is a technique used in laboratories to amplify DNA fragments. This technique is used for rapid diagnosis of the presence of pathogens, for example. , antigenic test Test used to detect antigens (foreign substance, for example present on a pathogen, which stimulates an immune reaction (i.e. the production of antibodies)). or serology This involves measuring antibodies (produced by the body in response to the presence of a pathogen) in a blood sample. .

How is the disease treated or prevented ?

There is no specific treatment for dengue fever. Treatment is symptomatic, with analgesics and rehydration in the event of fever. Aspirin and anti-inflammatory drugs should be avoided as they increase the risk of haemorrhage. In severe cases, urgent medical attention should be sought.

Prevention is mainly achieved by avoiding mosquito bites. 

A dengue vaccine (Qdenga) has been available in Belgium since April 2023. This vaccine reduces the risk of severe dengue infection. It has been approved for the prevention of all four serotypes of dengue fever and can be administrated to adults and children over the age of 4.

For more information on the recommendations for use of the vaccine, see the opinion of the French National Board of Health.