Mosquitoes as carriers of West Nile fever

Mosquitoes can transmit dangerous diseases

31.01.2013

Mosquitoes often play a significant role in the spread of tropical diseases to more northern regions. For example, in the United States last year, an outbreak of West Nile fever was observed, with mosquito transmission being the dominant factor. At the congress, scientists at the Hamburg Bernhard Nocht Institute for Tropical Medicine (BNI) explain the risk of mosquitoes transmitting tropical viruses in Germany „Infection epidemiology“ in Hamburg.

The risk of mosquitoes transmitting tropical viruses is one of the main topics of the congress. A possible spread of the West Nile virus in Germany is currently the focus of research interest. Some Southern European countries and the US have been suffering from a wave of infections over the past year, with mosquito transmission of the pathogens playing a major role. It is still unclear, however, whether the pathogens multiply in the mosquitoes. „The question is whether the viruses can multiply in the mosquitoes and thus survive“, said the biologist of the BNI, Stefanie Müller, to the news agency „dpa“.

Mosquito research in the high-security laboratory
Numerous mosquitoes caught in Germany have already been infected with West Nile viruses by the BNI researchers in the lab to find out what the risk of transmission of West Nile fever is. The key question is to what extent the pathogens can survive in the mosquitoes and multiply. The mosquitoes are fed in the high-security laboratories of the BNI with a mixture of fructose, blood and viruses, explained BNI biologist Stefanie Müller. Then you will „after a few days a part of the mosquitoes, so to speak, squashed, there is liquid left, in which then the viruses would have to be“, the expert continues. Three weeks later „we examine other mosquitoes and see if the viruses have multiplied“, reports Müller. However, it requires a variety of analyzes in order to come to a reliable conclusion. For exact results, therefore, many more mosquitoes would have to be examined. The scientists are therefore waiting eagerly for the end of the winter or the beginning of the mosquito season.

West Nile fever in the USA
While the West Nile virus is now widespread in the US, researchers fear that it will spread even more in Germany. In the US last year, the consequences of an outbreak of West Nile fever have been demonstrated. The information provided by the US Department of Health „Centers for Disease Control and Prevention“ (CDC), around 5,400 people in 48 US states were infected with West Nile virus and 243 people succumbed to the disease. Indications of the infection include flu-like symptoms such as fever, headache and body aches. However, these are often not perceived by those affected as a particular health risk. Also, many infected have no symptoms at all, so that the infection goes completely unnoticed. At worst, however, it threatens a life-threatening inflammation of the brain or the meninges, as the viruses can pass the blood-brain barrier. In the US, the West Nile virus was particularly easy to spread, as a special mosquito species, which stings both humans and birds, favored transmission, said the BNI expert. However, these mosquitoes of the Culex genus are hardly common in Germany. However, climate change has led to an increase in the number of species of mosquitoes that have come from southern regions in recent years. However, West Nile fever has so far only occurred in Germany as an introduced disease.

Genome research for the analysis of mosquitoes
To check whether the Culex genus, which was involved in the US in the spread of the West Nile virus, also occurs in Germany, is currently being taken with a novel genetic test, the domestic mosquito population under the microscope, report the researchers of the BNI , Here there is basically „two types of Culex pipiens, which behave differently but look identical“, explained the BNI biologist. Based on the genome of 17,000 captured mosquitoes from the summers of 2011 and 2012, the BNI scientists have studied the distribution of Culex mosquitoes in Germany. The results should also be included in a mosquito atlas, which reflects the spread of mosquitoes and the associated risk of infection.

EHEC, tuberculosis and multidrug-resistant germs
The „Infection epidemiology“ In addition to the risk of transmission of tropical diseases caused by mosquitoes, the congress in Hamburg is also dedicated to extraordinary events such as the 2011 EHEC epidemic and worldwide topics such as resistant hospital germs, tuberculosis bacteria and the special role of bats as a source of new viruses, reports the BNI. „At the international symposium, scientists will present, among other things, current techniques for investigating the origins and spread of infections“, so the message of the institute. Here, the researchers put great hope in the „Next Generation“ DNA sequencing, which should provide comprehensive information on the origin, virulence and drug resistance of pathogens. „The analysis of epidemics is making rapid progress through modern genome research, but fighting and prevention are difficult and persistent“, said Professor Rolf Horstmann, director of the Bernhard Nocht Institute for Tropical Medicine (BNI) and current spokesman for the Leibniz Institutes for Infection Research, the North German Institute for Infection Research „Leibniz Center Infection“. (Fp)

Also read:
New York mosquitoes infected with dangerous virus
Spread of the West Nile virus in Europe
Europe: West Nile fever is spreading
Dangerous tropical fever by bush mosquitoes
Climate change: Dengue fever reaches Europe
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Picture: Peashooter