This is an infectious encephalomyelitis of sheep and man occurring during spring and summer when the vectors like ticks are active. It is reported from British Isles and Iberian peninsula. The louping ill virus is a member of genus Flavivirus of the family Flaviviridae.
Epidemiology: The virus life cycle involves transmission between sheep by ticks,Ixodes ricinus, with occasional involvement of horses, cattle and deer.
Clinical signs: The disease is seasonal. The clinical signs include bi-phasic fever, nervous dysfunction, tremors, hyperexcitability and paralysis. The affected sheep exhibit a peculiar leaping gait due to ataxia.
Prevention and control: An inactivated cell culture vaccine is being used to control the disease.