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Classification according to ICD-10
G04 Encephalitis, myelitis, and encephalomyelitis
G04.2 Bacterial meningoencephalitis and meningomyelitis, not elsewhere classified
G04.8 Other encephalitis, myelitis and encephalomyelitis, post-infectious encephalitis and encephalomyelitis NOS
G04.9 Encephalitis, myelitis and encephalomyelitis, unspecified, ventriculitis (cerebral) onA
ICD-10 online (WHO version 2019)

An encephalitis (also encephalitis ; modern formation from ancient Greek ἐγκέφαλος (enképhalos) "brain", from ἐν "in" and κεφαλή (kephalē) "head", and the medical ending -itis for "inflammation") is an inflammation of the brain . It is mostly infectious , caused by viruses or - less often - by bacteria , protozoa or medically relevant fungi (such as Cryptococcus neoformans ). It can also occur as an autoimmune disease ( multiple sclerosis ). Infectious encephalitis is primarily characterized by neurological dysfunction . Are also the meninges with a meningitis (meningitis) with affected, one speaks of a meningoencephalitis . If the spinal cord is involved with inflammation of the spinal cord (myelitis), one speaks of encephalomyelitis .


In the United States , 7 in 100,000 people are hospitalized for encephalitis each year. In half of the cases, the cause of the encephalitis is unknown. Of the known causes, 20–50% are viruses . The herpes simplex virus (HSV) is the most common with 50-75%, followed by the varicella-zoster virus , enteroviruses and various arboviruses .

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Different encephalitides can be distinguished depending on the course, cause and exact part of the brain. According to the course, a distinction is made between acute , chronic and latent (without clinical symptoms) encephalitis.

A distinction is made according to the affected brain tissue:


The following symptoms are typical of encephalitis:

  • Change of character, altered cerebral state
  • Signs of inflammation: fever, fatigue, headache, etc.
  • cramps
  • neurological changes, e.g. B. visual disturbances, speech disorders
  • CSF changes : pleocytosis
  • Imaging: MRI mark
  • EEG changes

Depending on the severity and localization of the disease, the symptoms range from fever , headache and fatigue to paralysis , visual disturbances with double vision , cramps, unconsciousness and impaired perception and orientation. In the further course, there are also limitations in language ability and smell perception.


Almost always is an inflammation of the brain, the result of viral infections such as rabies , Japanese encephalitis , influenza , measles , rubella , mumps and by ticks transmitted encephalitis ( " Tick-borne encephalitis ") as the tick-borne encephalitis . Various herpes viruses such as herpes simplex viruses or the varicella zoster virus can also cause encephalitis ( herpes simplex encephalitis ). As a result of Covid-19 , brain inflammation was also detected that persisted after the acute symptoms had subsided.

A more recent discovery is the prion group of pathogens , which is responsible for transmissible spongiform encephalopathies .

When bacterial pathogens, for example, the coming listeriosis , of typhoid fever , the syphilis or Lyme disease into consideration. Parasitic encephalitides are caused by protozoa or worms (for example in cysticercosis ). A few fungi can cause mycotic encephalitis, e.g. B. as part of a cryptococcosis .

Finally, autoimmune diseases and para neoplastic diseases can lead to brain inflammation, for example in Bickerstaff encephalitis .

Infants and the very old are at greater risk of developing encephalitis.


Since a suspicion of encephalitis is often based on unspecific symptoms, which must be clarified by differential diagnosis ( e.g. exclusion of brain tumors, poisoning or tuberculosis), the following diagnostic methods in particular are used: Pathogen detection by lumbar puncture ( liquor diagnosis , if necessary with subsequent determination of the pathogen by polymerase chain reaction ) with additional evaluation of abnormalities during electroencephalography and magnetic resonance imaging .


Inflammation of the brain must be observed and treated as an inpatient in the hospital in order to recognize additional problems such as unconsciousness, convulsions or an organic psychosyndrome in good time and to be able to act properly. Encephalitis caused by bacteria is treated with antibiotics . In the event of an infection with herpes simplex viruses, specific therapy with intravenous administration of acyclovir is started and continued for at least three weeks. Certain forms can be prevented by vaccinations ( TBE ).


Mild encephalitis as part of the flu is often not noticed and goes away with the flu. Viruses such as B. Herpes simplex viruses can lead to serious illness with permanent damage. Paralysis and speech disorders can occur for a long time . In severe cases, intellectual disabilities and autism- like behavior disorders are possible. With bacterial encephalitis, the mortality is up to 50 percent. In some cases, inflammation of the brain can develop into Parkinson's disease as a long-term consequence .

Reporting requirement

Viral meningoencephalitis in Austria according to § 1 para. 1, point 2 Epidemics Act 1950 in case of illness and death notifiable . Doctors and laboratories, among others, are obliged to report this ( Section 3 Epidemics Act).

See also


  • Marianne Abele-Horn: Antimicrobial Therapy. Decision support for the treatment and prophylaxis of infectious diseases. With the collaboration of Werner Heinz, Hartwig Klinker, Johann Schurz and August Stich, 2nd, revised and expanded edition. Peter Wiehl, Marburg 2009, ISBN 978-3-927219-14-4 , pp. 74-76 ( infectious encephalitis ).
  • Heinz-Walter Delank: Neurology. 5th, revised and supplemented edition. Enke, Stuttgart 1988, ISBN 3-432-89915-7 , p. 148 f. ( Serous meningoencephalitis caused by fungi, protozoa and parasites ).
  • HW Pfister et al .: Bacterial (purulent) meningoencephalitis. Guideline of the German Society for Neurology. Working Group of Scientific Medical Societies , 2008.
  • Karl Wurm, AM Walter: Infectious Diseases. In: Ludwig Heilmeyer (ed.): Textbook of internal medicine. Springer-Verlag, Berlin / Göttingen / Heidelberg 1955; 2nd edition ibid. 1961, pp. 9-223, here: pp. 191-195.

Web links

Wiktionary: Encephalitis  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. Woodhouse's English-Greek Dictionary. The University of Chicago Library, accessed January 10, 2013 .
  2. ^ BP George, EB Schneider, A Venkatesan: Encephalitis hospitalization rates and inpatient mortality in the United States, 2000-2010. In: PLoS One . tape 9 , no. 9 , 2014, p. e104169 , doi : 10.1371 / journal.pone.0104169 , PMID 25192177 , PMC 4156306 (free full text).
  3. NM Vora, RC Holman, JM Mehal, CA Steiner CA, J Blanton, J Sejvar: Burden of encephalitis-associated hospitalizations in the United States, 1998-2010. In: Neurology . tape 82 , 2014, p. 443-51 , doi : 10.1212 / WNL.0000000000000086 , PMID 24384647 .
  4. ^ A Venkatesan, AR Tunkel, KC Bloch, et al .: Case definitions, diagnostic algorithms, and priorities in encephalitis: consensus statement of the International Encephalitis Consortium. In: Clinical infectious diseases . tape 57 , no. 8 , 2013, p. 1114-28 , doi : 10.1093 / cid / cit458 , PMID 23861361 , PMC 3783060 (free full text).
  5. Jing Gao et al .: Sars-Cov-2: Underestimated damage to nervous system . In: Travel Medicine and Infectious Disease . March 24, 2020, doi : 10.1016 / j.tmaid.2020.101642 .