Font Size

Encephalitis (cont.)

Encephalitis Prognosis

The outcome of the disease varies and depends on factors such as initial cause, age, severity of the case, and strength of the immune system. For example, people who are HIV positive, have cancer, or who have other illnesses have a weaker immune system and are less able to withstand another disease. These patients have a wide range of outcomes that range from good to poor. In general, those people with mild cases and otherwise relatively good health usually will recover without any problems. Poorer outcomes can be summarized as follows:

  • The death rate for certain patients with 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 rates that range from 0.3% to 60% of the people infected, usually within the first week of illness.
  • In untreated cases of herpes encephalitis, 50%-75% of people die within 18 months. Treatment with acyclovir (Zovirax) can increase survival up to 90%.
  • Patients with AIDS or chemical (alcohol) encephalitis often have only a fair to poor outcome.

The cause of the encephalitis has an important bearing on outcomes; as medicine advances, the prognosis may improve for some causes. Readers are encouraged to research other specific articles and links to get more details about potential treatments that improve outcome for each cause of encephalitis.

Medically reviewed by Robert Cox, MD; American Board of Internal Medicine with subspecialty in Infectious Disease


Anderson, Wayne E. "California Encephalitis." June 17, 2011. <>.

Howes, David S. "Encephalitis." Jan. 6, 2012; <>.

United States. Centers for Disease Control and Prevention. "Arboviral Encephalitides." June 19, 2007. <>.

United States. Centers for Disease Control and Prevention. "Questions and Answers About Japanese Encephalitis." Mar. 12, 2010. <>.

United States. National Institute of Neurological Disorders and Stroke. "NINDS Rasmussen's Encephalitis Information Page." Dec. 19, 2011. <>.

Medically Reviewed by a Doctor on 3/31/2015

Must Read Articles Related to Encephalitis

Brain Infection
Brain Infection Our brain, the spinal cord...learn more >>
Lyme Disease
Lyme Disease Lyme disease, sometimes referred to as Lyme infection, is a bacterial illness, transmitted to humans by the bite of deer ticks (Ixodes ticks) carrying a bacteri...learn more >>
Meningitis in Children
Meningitis in Children Meningitis is an inflammation of the membranes that surround the spinal cord or brain. Bacterial or viral infection are the typical causes of meningitis. Sympto...learn more >>

Patient Comments & Reviews

The eMedicineHealth doctors ask about Encephalitis:

Encephalitis - Symptoms

What symptoms did you experience with your encephalitis?

Read What Your Physician is Reading on Medscape

Encephalitis »

Encephalitis, an inflammation of the brain parenchyma, presents as diffuse and/or focal neuropsychological dysfunction.

Read More on Medscape Reference »

Medical Dictionary