Encephalitis is a condition characterized by inflammation of the brain. The condition may be caused by a direct viral infection of the spinal cord and brain (primary encephalitis); it may also result from complications of a current viral infection (secondary encephalitis). Encephalitis can cause a wide range of symptoms, such as sudden fever, headache, drowsiness, confusion, and vomiting. In extreme cases, complications can include brain damage, seizures, and death. People with weakened immune systems are at the highest risk of contracting encephalitis.