Encephalitis is irritation and swelling (inflammation) of the brain, most often due to infections.
See also: Meningitis
Encephalitis is a rare condition. It occurs more often in the first year of life and decreases with age. The very young and the elderly are more likely to have a severe case.
Encephalitis is most often caused by a viral infection. Many types of viruses may cause it. Exposure to viruses can occur through:
Different viruses will occur in different locations. Many cases will tend to cluster in a certain season.
Encephalitis caused by the herpes simplex virus is the leading cause of more severe cases in all ages, including newborns.
A number of viruses for which there is now a vaccine may also cause encephalitis. These include:
Other viruses that cause encephalitis include:
The virus causes inflammation of brain tissue. The brain tissue swells (cerebral edema), which may destroy nerve cells, cause bleeding in the brain (intracerebral hemorrhage), and brain damage.
Other causes of encephalitis may include:
Nath A. Berger JR. Acute viral encephalitis. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 439.
Beckham JD, Tyler KL. Encephalitis. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 87.
© 2011 University of Maryland Medical Center (UMMC). All rights reserved.
UMMC is a member of the University of Maryland Medical System,
22 S. Greene Street, Baltimore, MD 21201. TDD: 1-800-735-2258 or 1.866.408.6885