The origin of Encephalitis is unknown. It is the inflammation of the brain that is caused due to infections and mostly by a viral infection. The disease decreases with age and sever cases are mostly reported with the elderly and the very young. Read more details at en.wikipedia.org/wiki/Encephalitis
West Nile encephalitis is an infection of the brain that is caused by a virus known as the West Nile virus. First identified in Uganda in 1937, the virus is commonly found in Africa, West Asia, and the Middle East.