The role of climate change in a developing threat: the case of bluetongue in Europe

There is a solid theoretical basis for expecting climate change to have a considerable effect on the infectious diseases of humans, animals and plants. Vector-borne diseases are the most likely to be affected. It is, however, rare to observe such impacts, as diseases are also influenced by many other drivers, some of which may have stronger effects over shorter time scales than climate change. Nevertheless, there is evidence that our warming climate has already influenced some animal diseases, of which bluetongue is considered a prime example. Bluetongue emerged dramatically in southern Europe after 1998 and in northern Europe from 2006. While the speed and scale of this emergence is a challenge to explain, there is evidence, principally from the development of climate-driven models, that recent climate change has played a significant role. Climate-driven models point to an increase in the risk of bluetongue transmission in Europe in recent decades, caused by an increased suitability of parts of southern Europe for the Afro-tropical biting midge, Culicoides imicola, as well as an increase in the vectorial capacity of indigenous Culicoides vectors in northern Europe. Farm-to-farm transmission models of bluetongue in England and Wales under predicted climatic conditions further suggest that, under high-emission scenarios, the scale of future outbreaks could far exceed those experienced to date. The role of climate change in the developing threat of animal disease is, therefore, likely to be economically and socially costly, unless lower emission targets can be set and followed.