Between 1750 and 1800, France and Germany experienced minor epidemics of "coma somnolentum" with features of Parkinsonism, including hyperkinetic hiccup, myoclonus, chorea, and tics. Between 1848 and 1882, Paris-based neurologist Jean-Martin Charcot documented many isolated cases of juvenile Parkinsonism, associated with diplopia, oculogyria, tachypnoea, retropulsion, and obsessional disorders, which were almost certainly post-encephalitic in origin. In 1890 in Italy, following the influenza epidemic of 1889–1890, a severe epidemic of somnolent illnesses (nicknamed the "Nona") appeared. For the few survivors of the Nona, Parkinsonism and other sequelae developed in almost all cases. Between 1915 and 1926, a world-wide encephalitis lethargica pandemic occurred, impacting nearly 5 million people and killing an estimated 1.6 million people. Pandemic of 1915–1926
In the winter of 1916–1917, a "new" illness suddenly appeared in Vienna and other cities, and rapidly spread world-wide over the next three years. Earlier reports appeared throughout Europe as early as the winter of 1915–1916, but communication about the disease was slow and chaotic, given the varied manifestation of symptoms and difficulties disseminating information in wartime. Until Constantin von Economo identified a unique pattern of damage among the brains of deceased patients and introduced the unifying name encephalitis lethargica, reports of the protean disease came in under a range of names: botulism, toxic ophthalmoplegia, epidemic stupor, epidemic lethargic encephalitis, acute polioencephalitis, Heine-Medin disease, bulbar paralysis, hystero-epilepsy, acute dementia, and sometimes just "an obscure disease with cerebral symptoms."
External links
National Institute of Neurological Disorders and Stroke
Mystery of the Forgotten Plague: BBC news item about the tracing of the infectious agent in encephalitis lethargica