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Definition

By Mayo Clinic staff

Although the term "encephalitis" literally means "inflammation of the brain," it usually refers to brain inflammation resulting from a viral infection. The severe and potentially life-threatening form of this disease is rare. Experts suspect that the actual incidence of encephalitis is probably much higher — but because most people have such mild signs or symptoms, many cases go unrecognized.

Encephalitis occurs in two forms — a primary form and a secondary form. Primary encephalitis involves direct viral infection of your brain and spinal cord. In secondary encephalitis, a viral infection first occurs elsewhere in your body and then travels to your brain.

Seeing your doctor and receiving timely treatment is important because the course of the encephalitis is unpredictable.

References
  1. Encephalitis and meningitis fact sheet. National Institute of Neurological Disorders and Stroke. http://www.ninds.nih.gov/disorders/encephalitis_meningitis/detail_encephalitis_meningitis.htm. Accessed March 21, 2009.
  2. Tyler KL. West Nile virus infection in the United States. Archives of Neurology. 2004;61:1190.
  3. Johnson RP. Viral encephalitis in adults. http://www.uptodate.com/home/index.html. Accessed March 12, 2009.
  4. Willoughbly RE Jr, et al. Encephalitis, meningoencephalitis, acute disseminated encephalomyelitis, and acute necrotizing encephalopathy. In: Long SS, et al. Principles and Practice of Pediatric Infectious Diseases. 3rd ed. Philadelphia, Pa.: Churchill Livingstone; 2008. http://www.mdconsult.com/das/book/body/127224884-3/819357724/1679/50.html#4-u1.0-B978-0-443-06687-0..50049-7--cesec19_1078. Accessed March 21, 2009.
  5. Eastern equine encephalitis fact sheet. Centers for Disease Control and Prevention. http://www.cdc.gov/ncidod/dvbid/arbor/eeefact.htm. Accessed March 21, 2009.
  6. St. Louis encephalitis fact sheet. Centers for Disease Control and Prevention. http://www.cdc.gov/ncidod/dvbid/sle/Sle_FactSheet.html. Accessed March 21, 2009.
  7. LaCrosse encephalitis. Directors of Health Promotion and Education. http://www.dhpe.org/lacenceph.asp. Accessed March 21, 2009.
  8. Peters CJ. Infections caused by arthropod- and rodent-borne viruses. In: Fauci AS, et al. Harrison's Principles of Internal Medicine. 17th ed. New York, N.Y.: McGraw-Hill Medical; 2008. http://www.accessmedicine.com/content.aspx?aID=2895916. Accessed March 21, 2009.
  9. Encephalitis. The Merck Manuals: The Merck Manual for Healthcare Professionals. http://www.merck.com/mmpe/print/sec16/ch217/ch217c.html. Accessed March 21, 2009.
  10. Voelker R. Effects of West Nile virus may persist. Journal of the American Medical Association. 2008;299:2135.
  11. Insect repellant use and safety. Centers for Disease Control and Prevention. http://www.cdc.gov/ncidod/dvbid/westnile/qa/insect_repellent.htm. Accessed March 22, 2009.
  12. Follow safety precautions when using DEET on children. American Academy of Pediatrics. http://www.aap.org/family/wnv-jun03.htm. Accessed March 22, 2009.

DS00226

May 5, 2009

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