Vortrag, Klimawandel, Parasiten und Infektionskrankheiten - eine globale Herausforderung (Workshop des "netzwerk-forum zur biodiversitätsforschung deutschland - nefo"), Berlin: 03.03.2011 - 04.03.2011
During the last decades the disease vector Aedes albopictus (Asian Tiger mosquito) has rapidly established itself around the globe and ranks today among the first 100 of the "World's Worst" invaders. It has spread from its original distribution area in south-east Asia (Hawley, 1988) to at least 38 countries in North America, South America and Central America, Africa, Oceania and even Europe. The spread of Aedes albopictus raises serious public health concerns, due to its capacity to transmit 22 arthropod-borne viruses and two heartworms. From a European point of view, the medical importance of this species was highlighted in 2007, when the occurrence of the species was related to a chikungunya-epidemic in northern Italy. During the last decades dengue incidences are emerging significantly around the globe. Currently, about one fifth of the human population lives in dengue risk zones, which are mainly located in (sub-) tropical regions of Southeast Asia and the western Pacific. Dengue infections in European population mainly referred to returning travellers from tropical endemic regions (about 600 cases in German travellers in 2010). However, for the first time two autochthonous cases of dengue fever were recently diagnosed in South of France and furthermore, a dengue virus infection was reported from a German traveller returning from Croatia. In the face of climate change, the identification of European areas at risk, which provide climatically suitable conditions for the establishment of disease vector Aedes albopictus and temperature requirements for dengue virus amplification is of great importance for risk analysis. Here, we modelled the present distribution and the future climatic suitability of Aedes albopictus by means of the „environmental niche modelling“ (Software: MaxEnt, with over 1200 presence points worldwide) and the regional climate model COSMO-CLM (A1B und B1 scenario). Suitable areas for the establishment of Ae. albopictus are increasing in Western and Central Europe already in 2011 - 2040 and with some temporal delay also in Eastern Europe. Furthermore we considered the thermal constraints for the virus to accomplish its amplification inside the vector. We focused on the extrinsic incubation period (EIP: time interval between the acquisition of an infectious agent by a vector and the vector's ability to transmit the agent to a susceptible vertebrate hosts) which is mainly regulated by temperature. We transfer these findings to the changing European climate based on daily mean temperature data provided from COSMO-CLM (A1B and B1 scenario). Until now studies on the EIP of dengue virus in Aedes albopictus are missing and hence we used temperature constraints for virus amplification within the vector Aedes aegypti from two laboratory experiments. Results indicate a growing threat for virus amplification in Europe especially towards the end of this century. The southwest of the Iberian Peninsular appears to be especially threatened. Even in some parts of Central Europe, such as Southwest Germany, dengue virus amplification can no longer be excluded. Finally, we combined the findings for climatically suitable conditions for the establishment of the vector and temperature requirements for virus amplification in order to detect potential areas at risk for dengue infestation. Within the next decades, especially south and south-western parts of France, large parts of Italy, areas in the north-east of Spain and the Balkans seems to be at risk. Future studies will integrate further aspects, such as globalisation of trade and traffic. Policy and public health authorities have to consider these emerging risks in order to establish surveillance systems and develop adaption strategies. This project is part of the Bavarian research consortium “VICCI - Vector-borne Infectious Diseases in Climate Change Investigations“. Partner institutions are the Bavarian Health and Food Safety Authority, Comparative Tropical Medicine and Parasitology of the Ludwig-Maximilians University (Munich), the Institute of Microbiology, Immunology and Hygiene at the University of Erlangen, the Department of Biogeography at the University of Bayreuth and the Bundeswehr Institute of Microbiology.