Dengue fever A90.x

Viral disease transmitted by mosquitoes, characterized by the triad:

• fever
• exanthema
• joint, muscle and headache.

Complicated hemorrhagic courses are referred to as hemorrhagic degue fever or dengue shock syndrome.

Dengue viruses (DEN1-DEN4) are RNA viruses. Dengue viruses form a separate group in the genus Flavivirus of the Flaviviridae family, the prototype of which is the yellow fever virus. The CLDN1 protein acts as a receptor for the virus to enter the cell.

The incubation period is 4-10 days.

There is no complete cross-immunity between the human pathogenic subtypes DEN1-4, so that infection with any subtype is possible. It is therefore possible to contract dengue fever a maximum of 4 times.

In 2009, the classification of the dengue disease into:

• Dengue fever (DF)
• Dengue hemorrhagic fever (DHF)
• Dengue shock syndrome (DSS)

has been replaced by a new WHO classification. This distinguishes between

• Dengue without warning signs
• Things with wart with warning signs
• Severe dengue fever

Endemic in tropics and subtropics (also in highly urbanized areas!) outside Europe (Southeast Asia, South Pacific, Africa, Central and South America, Caribbean).About 2-3 billion people live in endemic areas worldwide. Incidence (worldwide): Approximately 50 million infections/year, including approximately 500,000 cases of dengue hemorrhagic fever (DHF) and 20,000 deaths (primarily children). The significant global spread trend is due to the worldwide decline in vector control for decades, the increase in urban breeding sites combined with increasing littering in poor areas of the tropics, and due to increased international migration and travel.

About 2,000 cases/year are reported nationwide, especially among vacation travelers (Thailand!) or migrants.

Recently, dengue fever infections also occurred at Lake Garda/Italy (Federal Foreign Office Notices 2023).

Infection with dengue viruses occurs from person to person through the bite of the vector (Aedes species, in particular Aedes aegypti, more rarely Aedes albopictus/so-called Asian tiger mosquito; diurnal; bite mainly at dusk).

Aedes albopictus is a small (3-4 mm), dark-colored mosquito with white stripes on the legs and a white marking on the neck shield (scutum), reminiscent of a lyre. Hence the name tiger mosquito. The proboscis is black. Females and males have the same markings, the females are usually slightly larger. Only the female mosquitoes suck blood after fertilization to cover their protein requirements for the production of offspring. The male mosquitoes feed mainly on nectar and other sweet plant juices. The females can also meet their energy requirements from this.1

All 4 serotypes cause identical symptoms. Classic dengue fever begins after an incubation period of 5-8 days with high fever, severe headaches, bone pain ("bone-breaking fever") and joint swelling.

Before the convalescence phase, a morbilliform or scarlatiniform exanthemadevelops , which is often diagnosed as "sunburn". Eye involvement (retroorbital pain), myalgia, arthralgia, petechiae and swelling of the lymph nodes are common. Afterwards, the patient walks strangely for a long time (dengue = daintiness).

Dengue with warning signs: in addition to the symptoms listed above, at least one of the following criteria is present:

• abdominal pain
• persistent vomiting
• edema
• mucosal bleeding
• lethargy
• restlessness
• hepatomegaly

Severe dengue (-hemorrhagic) fever (DHF) (see below hemorrhagic fever) was previously described as a two-phase disease: dengue fever with subsequent short-term remission (phase 1), followed by sudden deterioration with clinically significant bleeding in the skin and mucous membranes (phase 2), capillary leak syndrome, severe organ dysfunction (e.g. acute liver failure with transaminases >1000U/l, impaired consciousness.

Symptomatic, according to WHO guidelines. Cave! Aspirin in hemorrhagic diathesis should be avoided.

Monitoring of vital functions, sufficient fluid intake, in case of disseminated coagulopathy possibly heparin therapy.

Skin changes symptomatic with cooling lotions.

Haemorrhagic forms require immediate intensive medical treatment.

Exposure prophylaxis (in contrast to malaria also during the day) with repellents (DEET, Bayrepel), as well as with permethrin-impregnated mosquito nets at night.

Vaccination: 2 vaccines are now approved in Europe:

• ^Qdenga®: at the end of 2022 the dengue vaccine ^Qdenga® a tetravalent attenuated live vaccine that is directed against all 4 subtypes. This has also been approved in Germany since 2023 - from the age of 4 years. Travel vaccination: A basic immunization consisting of 2 vaccinations should be completed before travelling.
• ^Dengvaxia®: This live attenuated tetravalent vaccine was approved by the EMA for Europe in 2018. The approval applies to people between the ages of 9 and 45 who live in an endemic area. This vaccine is no longer recommended (Roth T 2025)

Please note! Mandatory reporting in case of pathogen detection or a hemorrhagic course of the disease in case of suspicion/illness/death!

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