Encephalitis is an inflammation of the brain. Usually the cause is a viral infection, but bacteria can also cause it. It can be mild or severe. Most cases are mild. You may have flu-like symptoms. With a mild case, you may just need rest, plenty of fluids, and a pain reliever.
Severe cases need immediate treatment. Symptoms of severe cases include
Severe headache
Sudden fever
Drowsiness
Vomiting
Confusion
Seizures
In babies, additional symptoms may include constant crying, poor feeding, body stiffness, and bulging in the soft spots of the skull.
Severe cases may require a stay in the hospital. Treatments include oral and intravenous (IV) medicines to reduce inflammation and treat infection. Patients with breathing difficulties may need artificial respiration. Some people may need physical, speech, and occupational therapy once the illness is under control.
NIH: National Institute of Neurological Disorders and Stroke