Encephalitis Lethargica: During and After the Epidemic is akin to a detective novel about a major medical mystery that remains unsolved. During the 1920s and 1930s a strange, very polymorphic condition affected much of the world although not at the same time everywhere and certainly not with the same symptoms. This condition, encephalitis lethargica, could cause death in a short period, or a Rip Van Winkle type of sleep that might last days, weeks...