There is a lot said about climate change and is it really happening. One area that doesn't get mentioned is the increase of tropical diseases in more temperate climates.
The meeting I attended yesterday was about Bluetongue, a disease of ruminants which is posing an ever increasing risk to the UK (I was very tempted to use a picture of a child with a blue tongue but then people would think it could be caught by humans, it can't, strictly ruminants). Bluetongue used to be a disease seen south of the mediterranean. In the 40 years prior to 1997 it only made two incusions into southern Europe. Since then it has made 12 incursions, 5 of them last year. And these incursions are getting further north, with Holland, France and Germany all affected.
It is the "why" that is of interest. Bluetongue is a vector borne disease, it cannot pass directly from one animal to another but needs a midge to transmit it. The main midge able to carry the disease was one that didn't live in Europe so there was no way the disease could spread. Two things have changed. The particular species of midge, Culicoides imicola, can now be found further north than ever before, thus carrying the disease further. But, even more interesting, the species of Culicoides in Northern Europe is changing. The higher temperatures have altered the little blighters at a cellular level and they are now able to carry the virus because it can cross their gut membrane. Climate change means that this virus can travel further in more species vectors than ever before.
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