Adult encephalitis is mainly seen in the following causes: i. If adults have viral infections, such as having upper respiratory tract infections or diarrhea or abdominal infections, and their dizziness, headache, nausea, and vomiting, it is considered to be an intracranial infection, and a cranial magnetic resonance examination can be done. Second, for example, the adult resistance is relatively low, when the tuberculosis bacteria are easy to invade into the brain to cause tuberculous meningitis.3, if there is the effect of immunodeficiency virus, it is also easy to cause fungal meningitis. Third, if the adult has a tumor, it can also cause autoimmune-related encephalitis. So adult encephalitis is mainly seen in the above common causes.