Climate change Dengue fever reaches Europe

Dengue fever reaches France: For the first time a man has been infected with a tropical disease, even though the virus has not been introduced by a journey.

(15.09.2010) Tropical diseases are becoming increasingly common in Europe. Blame are the increased temperatures in the wake of climate change, which favor the spread of exotic disease carriers to Europe. Thus, for the first time, a man on Nice has been infected by a mosquito bite with dengue fever. So far, only introduced infections had occurred.

Dengue fever is the most common and fastest-spreading mosquito-borne viral infection in the world. The number of cases has increased thirty-fold between 1960 and 2010 and the World Health Organization (WHO) estimates that 50 to 100 million people annually become infected with dengue fever. In about 500,000 people, the disease is severe and about 22,000 people, mostly children, die each year from the effects of the infection. In Germany, 290 people fell ill with dengue fever last year, with all infections being transmitted by foreign travelers.

The disease course of dengue fever is characterized by nonspecific symptoms that are often similar to those of a severe flu. However, it can also internal bleeding and severe disease course life-threatening „Dengue Haemorrhagic fever“ or that „Dengue shock syndrome“ occur. „The dengue viruses are like the triggers of West Nile fever, Japanese encephalitis or yellow fever to the flaviviruses“, explains Prof. Matthias Niedrig from the Robert Koch Institute (RKI) in Berlin to Welt Online. There are four types that are regionally distributed differently. „If you have one type, there is no immunity to the other three“, On the contrary, if an already infected patient is infected with another type, the likelihood of a more severe illness is extremely high. It is not yet clear why a secondary infection can reach life-threatening proportions. However, according to Prof. Niedrig, there are indications that the antibodies that form during a first infection negatively influence the immune system's response to a second infection.

Dengue fever has so far been widespread in tropical and subtropical regions such as South America, Southeast Asia or East and West Africa, as the carriers of the disease are also prevalent here. The female yellow fever mosquito (Aedes aegypti) and the Asian tiger mosquito (Aedes albopictus), which has recently become common in Europe, are considered to be the most important carriers of the virus, although other mosquito species are also suitable for transmission of pathogens (vector competence). Where the mosquito species are represented, there is also the risk of dengue fever infection. As Gerhard Dobler from the Institute of Microbiology of the German Armed Forces in Munich emphasized: „In some regions you always have to expect to be infected with dengue“ and added: „But there are also regular epidemics in countries that are otherwise not so severely affected.“ For example, two female tourists in Egypt were infected with the dengue virus for the first time in June, with experts warning of a further spread of the pathogen. A dengue fever disease is notifiable in Germany, Austria and Switzerland as soon as suspected.

According to media reports, the French Caribbean Islands have been hit by a dengue fever wave of around 60,000 infected and 17 deaths for several months, and the dengue virus has now reached the French Mediterranean coast. As this is not an imported disease, the French Ministry of Health is calling on the inhabitants of Nice to provide intensive mosquito repellent. Clothing that covers the body, sleeping under mosquito nets, insect repellent and covering any standing water are currently urgently required, according to the authorities. Similar measures should be taken by travelers visiting one of the world's dengue fever regions. There is no vaccine to protect against the dengue virus, but experts expect the availability of such a vaccine in the coming years.

With timely diagnosis, the dengue fever can usually be relatively successfully combat. So will „the disease (...) treated with remedies for fever and pain, possibly also with infusions“ explains Tomas Jelinek, Scientific Director of the Center for Travel Medicine in Düsseldorf. In any case, the doctors should be careful not to use active substances such as acetylsalicylic acid (ASA, aspirin), which impair blood clotting.

The biggest problem, according to the experts anyway in the corresponding diagnosis of tropical diseases, as these are less common in this country and therefore difficult for doctors to recognize. For example, diseases such as chikungunya fever or leishmaniasis first appeared in Europe in the past year. So far, mostly people were affected, who had recently visited one of the distribution areas of the corresponding disease, whereby the diagnosis was greatly facilitated. In the future, however, in some regions of Europe the risk of infection will be directly on the spot, which requires a rethink on the part of the doctors. (Fp)

Picture: Dr. Karl HERRMANN