African Horse Sickness

What is it? Viral infection transmitted by midges affecting heart and lungs. Infections can be acute, with animals dying suddenly without signs. Mortality rate up to 90%

Signs: fever, respiratory or circulatory distress, loss of appetite, excessive salivation

Where is it? Endemic in Africa, but hasn’t been seen in Europe since 1990, when it arrived in Spain via infected zebras. It has never been diagnosed in Britain

West Nile Virus

What is it? Viral infection transmitted by mosquitoes, causing inflammation of the brain and spinal cord. Mortality rate is about 35% in horses which show signs, but the ratio of clinical to sub-clinical cases is 1:2.5-1:5. Humans can be infected, not from horses but via mosquito bites

Signs: fever, encephalitis (inflammation of the brain) with nervous signs

Where is it? Africa, Europe, Asia, and — since 1999 — America, where it is now endemic. It has never been diagnosed in horses in Britain

  • Read H&H’s full report on the exotic equine disease threat currently facing horse owners in the current issue (15 November, ’07)