Louping-ill [lou-ping-ill] virus (LIV) is endemic to upland areas of the UK and Ireland but it can occur in other moorland and hilly areas where Ixodes ricinus (the sheep tick) is common. It is generally known as a disease of sheep but can affect cattle, horses, pigs, dogs, deer, red grouse, other wildlife species, and also humans. The first case of human Louping-ill was reported in 1934.
People become infected through the bite of infected ticks, or through contact with infected carcasses, sharp instruments, or air-borne particles of infected matter.