Encephalitis

In 2013, the International Encephalitis Consortium proposed clinical criteria for acute encephalitis consisting of 24 hours of altered level of consciousness, lethargy, or personality change and at least three additional supportive features. Although viruses are the most common cause of acute encephalitis, not all encephalitides are acute, viral, or even infectious. Chronic encephalitis can be pathologically similar to acute encephalitis, but the causative agents and clinical manifestations vary. Management of encephalitis is largely supportive; however, for many common encephalitides primary preventive approaches exist. This module reviews the epidemiology, manifestations, diagnosis, management, and prevention of various encephalitides, including herpes family encephalitis (herpes simplex virus, varicella-zoster virus, cytomegalovirus, human herpesvirus 6), arbovirus encephalitis (West Nile virus, eastern equine encephalitis virus, tick-borne encephalitis virus, Japanese encephalitis virus), other encephalitides associated with viruses (influenza virus, human immunodeficiency virus, John Cunningham virus, rabies virus), encephalitides associated with bacteria (Mycoplasma pneumonia