Outlook

The outcome of the disease varies and depends on factors such as age, severity of the case, and strength of the immune system. For example, people who are HIV positive, have cancer, or other illnesses have a weaker immune system and are less able to withstand another disease. In general, those with mild cases will recover without any problems.

• The death rate for viral encephalitis can be high.

• The St. Louis encephalitis virus can cause death in up to 30% of the cases.
  
  
• Japanese encephalitis can cause death in up to 60% of the cases, usually within the first week of illness.
  
  
• In untreated cases of herpes encephalitis, 50-75% of people die within 18 months. Acyclovir (Zovirax) can increase survival up to 90%.