Encefalitis

IDSA GUIDELINES

The Management of Encephalitis: Clinical Practice Guidelines by the Infectious Diseases Society of America
Allan R. Tunkel,1 Carol A. Glaser,2 Karen C. Bloch,3 James J. Sejvar,4 Christina M. Marra,5 Karen L. Roos,6 Barry J. Hartman,7 Sheldon L. Kaplan,8 W. Michael Scheld,9 and Richard J. Whitley10
Monmouth Medical Center, Long Branch, New Jersey; 2California Department ofHealth Services, Richmond; 3Vanderbilt University School of Medicine, Nashville, Tennessee; 4Centers for Disease Control and Prevention, Atlanta, Georgia; 5University of Washington School of Medicine, Seattle; 6Indiana University School of Medicine, Indianapolis; 7Weill Cornell Medical Center, New York, New York; 8Baylor College of Medicine, Houston, Texas; 9University of Virginia School of Medicine,Charlottesville; and 10University of Alabama at Birmingham
1

Guidelines for the diagnosis and treatment of patients with encephalitis were prepared by an Expert Panel of the Infectious Diseases Society of America. The guidelines are intended for use by health care providers who care for patients with encephalitis. The guideline includes data on the epidemiology, clinical features, diagnosis,and treatment of many viral, bacterial, fungal, protozoal, and helminthic etiologies of encephalitis and provides information on when specific etiologic agents should be considered in individual patients with encephalitis. EXECUTIVE SUMMARY Encephalitis is defined by the presence of an inflammatory process of the brain in association with clinical evidence of neurologic dysfunction. Of the pathogensreported to cause encephalitis, the majority are viruses. However, despite extensive testing, the etiology of encephalitis remains unknown in most patients. Another major challenge for patients with encephalitis is to determine the relevance of an infectious agent identified outside of the CNS; these agents may play a role in the neurologic manifestations of illness but not necessarily by directlyinvading the CNS. In addition, it is important to distinguish between infectious encephalitis and postinfectious or postimmunization encephalitis or encephalomyelitis (e.g., acute disseminated encephalomyelitis [ADEM]), which may be mediated by an immunologic response to an antecedent antigenic stimulus from an infecting microorganism or immunization. Noninfectious CNS diseases (e.g., vasculitis,collagen vascular disorders, and paraneoplastic syndromes) can have clinical presentations similar to those of infectious causes of encephalitis and should also be considered in the differential diagnosis. In the approach to the patient with encephalitis, an attempt should be made to establish an etiologic diagnosis. Although there are no definitive effective treatments in many cases ofencephalitis, identification of a specific agent may be important for prognosis, potential prophylaxis, counseling of patients and family members, and public health interventions. Epidemiologic clues that may help in directing the investigation for an etiologic diagnosis include season of the year, geographic locale, prevalence of disease in the local community, travel history, recreational activities,occupational exposure, insect contact, animal contact, vaccination history, and immune status of the patient. Various clinical clues may also be helpful to physicians in considering specific etiologies. The diagnostic evaluation of a patient who presents with encephalitis needs to be individualized and should be guided by epidemiologic and clinical clues and labIDSA Guidelines for Management ofEncephalitis • CID 2008:47 (1 August) • 303

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Received 9 April 2008; accepted 23 April 2008; electronically published 26 June 2008. It is important to realize that guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special...