A disease in which the white and gray matter of the brain to become inflamed causing the brain to swell. Encephalitis is caused by the presence of a virus or bacteria in the body and is often linked to meningoencephalitis. The severity and type of symptoms patients present depend on the area of the brain that has become infected. Symptoms can include vomiting, fever, stiff neck or back, drowsiness, seizures, paralysis, and more.