Encephalitis

Encephalitis is the inflammation of the brain by blood-borne immune cells. It is not to be confused with neuroinflammation, which is the modern inflammation of the nervous system by tissue-resident immune cells. Unlike with neuroinflammation, encephalitis is associated with swelling of the brain and can be detected using magnetic resonance imaging (MRI).

Encephalitis is normally caused by a virus, vaccine or when something else that causes inflammation. Encephalomyelitis is when the inflammation affects the spinal cord as well as the brain.

Viral encephalitis
Encephalitis can be caused by many different viruses, including:
 * adenovirus
 * cytomegalovirus
 * encephalomyelitis virus (Western equine or Eastern equine)
 * Ebola virus
 * Epstein-Barr virus
 * enteroviruses including coxsackieviruses, echo viruses and poliovirus
 * flaviviruses, which causes Japanese encephalitis
 * herpes simplex
 * herpes zoster virus (shingles)
 * La Crosse Virus, causing La Crosse or California encephalitis
 * lassa virus
 * lymphocytic choriomeningitis virus
 * measles
 * Murray Valley encephalitis virus
 * rabies virus
 * Rocio virus
 * rubella
 * St. Louis encephalitis virus, a flavivirus
 * varicella zoster virus (chickenpox)
 * Venezuelan equine encephalitis virus
 * West Nile virus

Research
In 2020, the Open Medicine Foundation announced a study investigating brain fog in patients with herpes simplex encephalitis, including following those patients over time to see which developed ME/CFS.

Learn more

 * Encephalitis - Merck Manuals
 * Viral encephalitis - Better Health, Australia
 * ICD-11 - World Health Organization