Also known as bovine spongiform encephalopathy, it is an illness of the cattle that destroys their brain and central nervous system. The brain has holes and feels spongy. It is fatal disease, having long incubation period. Humans, who have eaten nerve cells of affected cattle, may get a form of this disease known as variant Creutzfeldt-Jakob disease. The causing agent is known to be misfolded protein known as prion. Some findings also suggest that this disease is also caused by genetic mutation. So people must avoid taking by products of the affected cattle to be free from any worries.