health

The prognosis for recovery from encephalitis depends on the virus or
other disease agent that is causing the infection, the patient’s age, and his
or her general state of health. In general, infants and the elderly are at the
greatest risk of death from encephalitis.
People with mild cases of encephalitis usually recover without longterm
complications.

The prognoses for specific types of encephalitis are as follows:

• Rabies encephalitis: 100 percent mortality.
  
• Japanese encephalitis: 60 percent mortality, usually within the first
  week of illness.
  
• Untreated HSV encephalitis: 50–75 percent of patients die within
  eighteen months. The fatality rate drops to 20 percent in patients
  treated with acyclovir. Forty percent of survivors have long-range
  learning disabilities, epilepsy, movement disorders, memory loss,
  and psychiatric problems.
  
• St. Louis encephalitis: 30 percent mortality.
  
• West Nile virus: 10 percent mortality.