Poster, INTERNATIONAL CONFERENCE EDEN 2010 - Emerging Vector-borne Diseases in a Changing European Environment, Montpellier: 10.05.2010 - 12.05.2010
Abstract:
Aedes vexans and Ae. cinereus which are native mosquitoes in Europe are considered to be competent vectors of arborviruses there (Tahyna Virus, Snowshoe Hare virus and only Ae. Cinereus: Sindbis Virus). Feeding on birds and mammals, Ae. vexans and Ae. cinereus are also known to be bridge vectors for West Nile virus (WNV) in other parts of the world such as North America. There WNV lead to an epidemic outbreak ten years ago. The virus conquered the North American continent within a few years after introduction. New introductions of WNV and an increasing activity in Europe (Austria, Hungary, Italy, Romania and Turkey) were observed. This raises the question whether native mosquitoes of the genus Aedes may play a future role as WNV vectors, establishing a natural European foci. Beside biological and genetic factors in the transmission cycle of arborviruses like virus load above threshold, presence of non immune hosts, there are several ecological components which determine the process. Climate change alters thermal and hydrological conditions throughout Europe and will therewith influence also pathogen, vector and host distribution. In case of WNV modified bird migration behaviour may play an interesting role. Furthermore intensity and quantity of extreme climatic events are expected to increase. Human outbreaks of WNV seem to be triggered by above-average and below-average rainfall. On the other hand, non native, invasive aedine mosquito species (Ae. albopictus and Ae. japonicus) are of medical importance in Europe, too. Ae. albopictus is a competent laboratory vector of at least 23 arboviruses. Both, Ae. albopictus and Ae. japonicus were detected as highly susceptible to WNV infection in North America and they are in rapid extension of their dispersal area. This spread is strongly driven by human activities, such as transport, travelling and increased connectivity of potential habitats across regions. Beyond, even continents are connected nowadays by fast transport facilities. Introductions happen by chance, but the establishment of viable populations depends on climatic and further environmental habitat restrictions respectively. Some species, however, do not depend on large-scale naturally moist ecosystems for reproduction, but can establish offspring even in small accumulations of water like small containers filled with water. The establishment and adjacent dispersal of Ae. albopictus in Southern (since 1986) and Northern America (since 1985) and in Italy (since 1990) and the recent emergence of Ae. japonicus in Switzerland demonstrate that these vectors can hardly be controlled. As a consequence early warning systems are needed. We interlink current and future suitable climate conditions in Europe for aedine species with possible vector invasion pathways like harbours, airports and highways. Moreover introductions of pathogens for example by infected returning travellers as well as by migratory birds are considered. Combining climate projections for vector and pathogen and their dispersal mechanisms for the future development may contribute to the identification of risk areas.