Mosquitoes as carriers of West Nile fever

Mosquitoes as carriers of West Nile fever

Mosquitoes can transmit dangerous diseases

Mosquitoes often play an important role in the spread of tropical diseases to northern regions. For example, an outbreak of West Nile fever was observed in the United States last year, in which transmission by mosquitoes was considered a key factor. Scientists at the Bernhard Nocht Institute for Tropical Medicine (BNI) in Hamburg explain the risk of transmission of tropical viruses by mosquitoes in Germany at the "Infection Epidemiology" congress in Hamburg.

The risk of transmission of tropical viruses by mosquitoes is one of the main topics of the congress. The research interest is currently focusing on a possible spread of the West Nile virus in Germany. Some southern European countries and the United States had to deal with a wave of infections last year, with the transmission of the pathogens by mosquitos playing an important role. However, it is still unclear whether the pathogens also multiply in the mosquitoes. "The question is whether the viruses can multiply in the mosquitoes and survive", BNI biologist Stefanie Müller told the news agency "dpa".

Mosquito research in the high-security laboratory Numerous mosquitoes caught in Germany have already been infected with West Nile viruses in the laboratory by the BNI researchers in order to find out what the risk of transmission of West Nile fever is. The key question is to what extent the pathogens can survive and multiply in the mosquitoes. The mosquitoes are fed with a mixture of fructose, blood and viruses in the BNI's high security laboratories, explained the BNI biologist, Stefanie Müller. Afterwards, "after a few days, some of the mosquitoes are mashed up, so to speak, there is liquid left in which the viruses should then be located," continued the expert. Three weeks later, "we are examining other mosquitoes and seeing if the viruses have multiplied," reports Müller. However, a large number of analyzes are required to arrive at a reliable statement. Many more mosquitoes would have to be examined for exact results. The scientists are therefore eagerly awaiting the end of winter or the start of the mosquito season.

West Nile fever in the USA While the West Nile virus is now widespread in the USA, the researchers fear an increased spread in Germany as well. In the United States, the consequences of an outbreak of West Nile fever were shown last year. According to the Centers for Disease Control and Prevention (CDC), approximately 5,400 people in 48 US states were infected with the West Nile virus and 243 died of the disease. Indications of the infection are flu-like symptoms such as fever, headache and body aches. However, those affected are often not perceived as a special health risk. Also, many infected people have no complaints at all, so the infection goes completely unnoticed. In the worst case, there is a risk of life-threatening inflammation of the brain or the meninges, since the viruses can cross the blood-brain barrier. The West Nile virus was able to spread particularly easily in the USA, as a special mosquito species that bites both humans and birds favored the transmission, the BNI expert explained. However, these mosquitoes of the Culex genus have so far hardly been found in Germany. However, climate change has led to an increase in the number of mosquito species that originally come from southern regions. However, West Nile fever has so far only occurred in Germany as an introduced disease.

Genome research to analyze the mosquitoes In order to check whether the Culex genus, which was involved in the spread of the West Nile virus in the USA, also occurs in Germany, a new genetic test is currently being used to examine the native mosquito population, report the BNI researchers. There are basically "two types of Culex pipiens (common mosquitoes) that behave differently but look identical," explained the BNI biologist. On the basis of the genetic makeup of 17,000 mosquitoes caught in the summers of 2011 and 2012, the BNI scientists examined the distribution of the Culex mosquitoes in Germany. The results should also flow into a mosquito atlas, which reflects the spread of the mosquitoes and the associated risk of infection.

EHEC, tuberculosis and multidrug-resistant germs In addition to the risk of transmission of tropical diseases caused by mosquitoes, the "Infection Epidemiology" congress in Hamburg is also devoted to extraordinary events such as the EHEC epidemic 2011 and global issues such as resistant hospital germs, tuberculosis bacteria or the special role of bats as a source for new viruses, reports the BNI. "At the international symposium, scientists will, among other things, present current techniques for researching the origins and spread of infections," the institute said. Here, the researchers are placing great hope in the “next generation” of DNA sequencing, which is intended to 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 combating and preventing them are and remain difficult," explained Professor Rolf Horstmann, head of the Bernhard Nocht Institute for Tropical Medicine (BNI) and current spokesman for the association of North German Leibniz Institutes for infection research, the "Leibniz Center Infection". (fp)

Also read:
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Spread of the West Nile Virus in Europe
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Climate change: dengue fever reaches Europe
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Video: West Nile virus - causes, symptoms, diagnosis, treatment, pathology (September 2020).