Back to today’s briefing

Story perspectives

Encephalitis Lethargica: A Century-Old Mystery Lingers

5/23/2025

38 6

Summary

Story summary

Encephalitis lethargica, first identified by Constantin von Economo in 1917, swept through the world, infecting over a million and claiming 500,000 lives between the 1910s and 1930s. Survivors faced debilitating neurological disorders, yet the true cause remains a mystery, even as cases have sharply declined since the 1940s.

1 of 1

Story summary

Encephalitis lethargica, first identified by Constantin von Economo in 1917, swept through the world, infecting over a million and claiming 500,000 lives between the 1910s and 1930s. Survivors faced debilitating neurological disorders, yet the true cause remains a mystery, even as cases have sharply declined since the 1940s.