Bluetongue is a disease that affects cattle, sheep, goats and deer, and is spread by infected Culicoides (midges), blood or semen. It does not harm humans.
Infected animals run a high temperature, suffer from depression, inflammation, ulceration, erosion and, in extreme cases, cyanosis of the tongue, resulting in a blue discoloration.
The tongue swells, particularly in sheep, and sometimes turns blue. Animals can abort, go lame and will either die within eight to 10 days or have a long slow recovery period with hair loss, sterility and growth delay.
The disease has spread rapidly from Mediterranean regions since 1999 - this is often linked to global warming - and reached Britain in September. In Europe it has moved as far north as Denmark.
A vaccine is being developed, which the EU hopes will control its inevitable spread.
