Type of publication:
Original Article in Series
Type of document:
Rubel, F; Brugger, K
Dynamics of infectious diseases according to climate change: The Usutu virus epidemics in Vienna.
1st International Conference of the International-Research-Forum-on-Game-Meat-Hygiene (IRFGMH) on Game Meat Hygiene in Focus,
Brno, CZECH REPUBLIC, Czech Republic,
JUN 18-19, 2009.
IN: Paulsen, P [Hrsg.]: Game meat hygiene in focus - Microbiology, epidemiology, risk analysis and quality assurance. The Netherlands, Wageningen Academic Publishers, pp. 173-198. ISBN: 978-90-8686-165-1.
As an example of the dynamics of infectious diseases in mid-latitudes, so far mainly observed in the subtropics and tropics, we discuss the Usutu virus (USUV) epidemics in Vienna, Austria. The USUV is an arbovirus, which is closely related to the West Nile virus. It caused mass mortalities mainly of blackbirds (Turdus merula). Infections of mammalian hosts or humans are rare. The USUV flavivirus persists in a natural transmission cycle between vectors (mosquitoes) and host reservoirs (birds) and leads - once endemic in a population - to periodic outbreaks. Following the recent work of Rubel et al. (2008) and Brugger and Rubel (2009), we present an epidemic model to explain the USUV dynamics in Austria. Within the model framework the USUV dynamics is mainly determined by an interaction of bird immunity and environmental temperature. We demonstrate that the USUV model is able to simulate the observations from the dead-bird surveillance 2001-2005. To investigate future scenarios, we entered temperature predictions from five global climate models into the USUV model and also considered four different climate-warming scenarios defined by the Intergovernmental Panel on Climate Change, IPCC (20 different model-scenario combinations). Long-term simulations cover the period 1901-2100. The results indicate that USUV will persist in the host population after the epidemic peak observed in 2003, but the next major outbreak is expected to occur not before 2019. USUV-specific annual blackbird-mortality time series predict that the outbreak frequency increases successively from the beginning to the end of the century. Additionally, we calculated the annually averaged basic reproduction number for the period 1901-2100. The latter depict that undetected major outbreaks before 2000 were unlikely, whereas it is likely that the USUV becomes endemic after 2040.