Climate change: dengue fever reaches Europe

Dengue fever reaches France: for the first time, a man has contracted a tropical disease, even though the virus was not brought in by a trip.

(09/15/2010) Tropical diseases are also becoming increasingly common in Europe. The guilt is the rising temperatures due to climate change, which favor the spread of exotic disease carriers to Europe. For example, a man in Nice has recently been infected with dengue fever by a mosquito bite. So far, only introduced infections have occurred.

Dengue fever is the most common and fastest spreading mosquito-borne virus infection worldwide. The number of cases increased thirtyfold between 1960 and 2010 and the World Health Organization (WHO) estimates that 50 to 100 million people are infected with dengue fever every year. Around 500,000 people develop the disease and around 22,000 people, mostly children, die annually from the consequences of the infection. In Germany, 290 people suffered from dengue fever last year, with all infections brought in by travelers abroad.

The course of the disease of dengue fever is characterized by unspecific symptoms that often resemble those of severe flu. However, internal bleeding and, if the course of the disease is severe, the life-threatening “dengue hemorrhagic fever” or the “dengue shock syndrome” can occur. "Like the triggers of West Nile fever, Japanese encephalitis or yellow fever, the dengue viruses are flaviviruses," explains Prof. Matthias Niedersig from the Robert Koch Institute (RKI) in Berlin to Welt Online. A distinction must be made between four types, which are regionally distributed differently. "If you get one type, there is no immunity to the other three," emphasizes the RKI specialist. On the contrary: If an already infected patient becomes infected with another type, the likelihood of a more severe course of the disease is extremely high. It has not yet been clarified why a second infection can be life-threatening. However, according to Prof. Low, there are indications that the antibodies that form during the first infection have a negative impact on the immune system's response to a second infection.

Dengue fever has so far been particularly prevalent in tropical and subtropical regions such as South America, Southeast Asia or East and West Africa, since the carriers of the disease are also widespread here. The female yellow fever mosquito (Aedes aegypti) and the Asian tiger mosquito (Aedes albopictus), which has also recently appeared in Europe, are considered the most important transmitters of the virus, although other mosquito species are also suitable for transmitting pathogens (vector competence). Where the mosquito species mentioned are present, there is also a risk of dengue infection. Gerhard Dobler from the Bundeswehr Institute for Microbiology in Munich also emphasized: "In some regions, you can always expect to be infected with dengue" and adds: "Epidemics also occur regularly in countries that are otherwise not as badly affected. “For example, two female tourists in Egypt were infected with the dengue virus for the first time in June, with experts warning at the time that the pathogen would not spread further. Disease with dengue fever is notifiable in Germany, Austria and Switzerland as soon as suspected.

After the French Caribbean islands have been hit by a wave of dengue fever with around 60,000 infected people and 17 deaths for several months, according to media reports, the dengue virus has now reached the French Mediterranean coast. Since it is not a disease that has been introduced, the French Ministry of Health calls on the residents of Nice to provide intensive mosquito protection. Body-covering clothing, sleeping under mosquito nets, insect repellants and covering all standing water are currently urgently required by the authorities. Similar measures should be taken by travelers visiting one of the dengue fever regions around the world. So far, there is no vaccine to protect against the dengue virus, but experts expect it to be available in the coming years.

With timely diagnosis, dengue fever can usually be fought relatively successfully. For example, "the disease (...) is treated with anti-fever and pain medication, possibly with infusions," explains Tomas Jelinek, scientific director of the Center for Travel Medicine in Düsseldorf. In any case, the doctors should take care not to use an active ingredient such as acetylsalicylic acid (ASA, aspirin) that affects blood clotting.

According to the experts, the biggest problem is the corresponding diagnosis of tropical diseases anyway, since these are not very common in Germany and are therefore difficult for doctors to recognize. For example, diseases such as Chikungunya fever or leishmaniasis first appeared in Europe in the past few years. So far, mostly people who have recently visited one of the distribution regions of the corresponding disease have been affected, which has made the diagnosis considerably easier. In the future, however, there is a risk of infection locally in some regions of Europe, which also requires a rethink on the part of doctors. (fp)

Picture: Dr. Karl HERRMANN /

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