Pandemic influenza 1918 and encephalitis lethargica: one, two or more culprits?
The etiology of encephalitis lethargica was controversial during the major epidemic of 1918-1926. Streptococcal infection, viral infection (including herpes and poliomyelitis) and other explanations were proposed for the sudden emergence of this disorder. The issue of whether it was causally linked to the influenza pandemic which occurred at about the same time was also hotly debated. By 1930 encephalitis lethargica was no longer routinely diagnosed and interest in the disorder waned, so that the causal agent remains unidentified. The influenza virus, on the other hand, was identified in 1930, effectively ending discussions regarding the etiology of influenza. A closer examination of the medical literature of the period suggests, however, that attributing the 1918/19 influenza solely to the influenza virus may be an oversimplification of this extraordinary pandemic. This has serious consequences for planning for future influenza epidemics.
Symposium. Encephalitis Lethargica
12th Annual Meeting of the International Society for the
History of the Neurosciences (ISHN)