We anticipate that this document, representing a synthesis of our discussions and supported by literature, will serve as a practical aid to clinicians evaluating patients with suspected encephalitis and will identify key areas and approaches to advance our knowledge of encephalitis.

Programme Hospitalier Recherche Clinique, Institut Pasteur, Inserm, French Public Health Agency.

Our prospective study provides an overview of the clinical and etiologic patterns of acute infectious encephalitis in adults in France. Herpes simplex virus 1 remains the main cause of encephalitis, but bacteria accounts for the highest case-fatality rates.