West Nile encephalitis (WNE) is a disease which is caused by the West Nile virus (WNV). The West Nile virus is passed by mosquitoes. The virus is most common in the Middle East, Africa, and Asia, but has now spread worldwide. It first came to the United States in 2002 and was passed from person to person through bites from infected mosquitos. Most people with the viral infection do not develop symptoms. However, those who do may develop a fever, headache, bodyaches, fatigue, and back pain. Signs and symptoms only last a few days. In some rare cases, West Nile encephalitis can progress from a WNV infection. Encephalitis describes an inflamation or swelling of the brain, which can cause neurological problems. Symptoms of West Nile encephalitis may include high fever, severe headache, stupor or coma, tremors or muscle jerking, partial paralysis or muscle weakness, loss of coordination, and pain. These symptoms may last for weeks and may become permanent. Medical treatment is critical to a good outcome, so seek medical attention if you or a loved one has any of the symptoms listed above.