Introduction

Abstract

During the winter of 1916/17 the first instances of a mysterious disease were recognized in Vienna, the harbingers of a new malady that would cause anxiety in Europe and the Western world for the next decade: ‘encephalitis lethargica’ or ‘epidemic encephalitis’, popularly known in many parts of the world as the ‘slee**’ or ‘sleepy sickness’. Following the great European EL epidemics of 1920–21 and a final, massive outbreak in the United Kingdom in 1924, the threat dissipated as mysteriously as it had begun, although cases continued to be reported into the 1930s, particularly in England and Germany, and perhaps for even longer in the Soviet Far East.