Senckenberg Research

SAW-Project: Vectors

Occurrence and vector competence of mosquitoes as vectors of viruses in Germany 


The Project:


Will infectious diseases such as West Nile fever, dengue fever and others transmitted by blood-sucking insects soon regularly occur in Central Europe?

The emergence of new epidemics and infectious diseases is favoured in our latitudes by rapidly increasing globalization, as well as factors such as climate change, population growth and biodiversity loss. Although we currently find ourselves in a phase of accelerated global extinction of species, the relationship between biodiversity change and emerging or resurgent diseases has so far received little attention. The connection between biodiversity and human health becomes, however, particularly clear when the spread of invasive species such as mosquitoes, rodents (as so-called vectors = carriers), and pathogens such as viruses, bacteria and parasites (as causes of disease) is considered. The distribution of vectors and infectious diseases has always been directly linked to human activities. Thus for example, with the help of human activities the hantavirus and West Nile virus and the causative agents of dengue, Rift Valley, chikungunya fevers and malaria have already overcome biogeographical barriers. In addition, higher temperatures affect the vector density in an area, and thus increase the likelihood of transmission of infectious agents. As a consequence, in the next few decades (10 to 50 years) the spread of vector-borne infectious diseases (VBID) will greatly increase.

  Bruthabitat   Eigelege   Larve und Puppe   Oc. communis

   Breeding habitat with old water (Bild: Antje Werblow; BiK-F); Eggs and larvae of Culex sp.; stadium 4 larvae and pupa; Imago of (Ochlerotatus
   communis); Pictures: Andreas Krüger (BNI)


Arboviruses (arthropod-borne viruses) are viruses transferred by arthropods (mosquitoes, ticks). Different viruses use mosquitoes either as a host or as transport, as a so-called vector, to move from one host organism to another. The microorganisms are taken up by the mosquito with a blood meal, and passed on in the saliva during the next bite. The diseases that they cause represent zoonoses (diseases that are transmissible from animals to humans). In nature they constantly circulate in wild animals such as birds or rodents. Occasionally infection of domestic and farm animals as well as humans takes place, and larger or smaller epidemics may result. The symptoms can vary greatly, ranging from flu-like symptoms, through encephalitis to fatal haemorrhagic fevers.

Mosquitoes are known worldwide as the main carriers of vector-associated infectious pathogens. It is estimated that about 49 different species of mosquitoes are native in Germany, at least some of which have a proven ability to act as vectors for certain pathogens such as the causative agent of malaria, which until sometime in the 1950s was indigenous in Germany as "marsh fever". More recently, particularly in the wake of climate change, discussion and research has been driven by the increasing possibility of the transmission of arboviruses, such as West Nile, Tahyna or Sindbis virus, and also the transfer of certain worms (Dirofilaria).

Both climatic and ecological changes can influence the spread and behavior of mosquitoes. In recent years it has for example been observed that Anopheles plumbeus, a native in Germany that has been shown to transmit imported strains of the highly pathogenic malaria parasite Plasmodium falciparum, has changed its breeding behaviour from a pure "tree cavity breeder" to a "rain barrel breeder" (such as in gardens), resulting in a much higher density of mosquitoes in the proximity of humans. Among the most commonly occurring mosquitos in Germany, also in urban environments, are Culex pipiens pipiens and C. p. molestus, two forms of the Culex pipiens complex. Both are considered to be carriers of the West Nile virus, which has spread everywhere in the United States in recent years and has in Europe in recent years increasingly undergone small epidemics. In addition, new establishment or introductions of mosquitoes are possible. Thus, the Asian tiger mosquito Aedes albopictus seems after its establishment in Italy to be slowly spreading northwards. In southern Germany, the first eggs of this species have recently been found. Among other diseases, A. albopictus carries the chikungunya virus, common in Africa and Asia, which in 2007 led to indigenous diseases in northern Italy.

To assess these risks, a "mosquito map of Germany" is being prepared. This is a collaborative project, involving the team of scientists led by Prof. Dr. Sven Klimpel of the Biodiversity and Climate Research Centre (BiK-F), the Senckenberg Nature Research Society and the Goethe University Frankfurt/Main as well as colleagues of the Bernhard Nocht Institute for Tropical Medicine Hamburg (BNI), the Senckenberg German Entomology Institute (SDEI), the KABS (German Mosquito Control Association) and other Senckenberg institutes in Dresden ,Görlitz, Gelnhausen and Frankfurt/Main. The first step is for the taxonomists to determine which species of mosquitoes now feel at home in Germany, so as to be able to identify changes in the local mosquito fauna and permit their early detection. In addition, using appropriate laboratory tests we are attempting to find out whether native species are able to transmit certain pathogens under given conditions (vector competence). This is the goal of the interdisciplinary research project "Occurrence and vector competence of mosquitoes as vectors of viruses in Germany", which is funded by the Leibniz Association with more than three quarters of a million euros.

Within the next few years we want to gain an overview of the distribution of species of mosquitoes and to ascertain which viruses they can transmit and harbour. Such reliable data are essential because they allow timely detection of a potential outbreak of an infectious disease and enable preventive measures to be taken. The core of the research project will be a database into which will flow the data for all collected mosquito material together with the viruses or pathogens detected in them. Each of the insects will practically represent a point on a map of Germany and finally we will have a distribution map that shows which mosquito species occurs where, and in what numbers.

Despite their medical significance, the current state of knowledge on the occurrence, distribution and vector competence of mosquitoes in Germany is patchy and based largely on outdated data. Unlike other European countries such as France, Belgium or the Netherlands, Germany has had no institutionally organized systematic collection of data. This nationwide research project will change this.

                                                                                                                                                                                              top of page