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Mystery Pandemic 'Sleeping Sickness' Still Puzzles
6 Jun
Summary
- A forgotten pandemic, encephalitis lethargica, killed half a million people.
- Its cause and transmission remain a profound medical mystery.
- Survivors often faced permanent personality changes or Parkinsonism.
A mysterious neurological syndrome known as encephalitis lethargica (EL), or "sleeping sickness," quietly impacted the world for over a decade in the early 20th century. This pandemic, occurring concurrently with the Spanish Flu, killed around five hundred thousand people and left hundreds of thousands more with severe, lasting impairments. The exact cause and transmission methods of EL continue to be a significant medical mystery, over a century after its first description.
EL presented with varied symptoms, ranging from hypersomnia to mania, making its diagnosis challenging. Some patients succumbed quickly, while others endured a prolonged struggle with the illness. A significant portion of survivors, estimated at 50 percent, experienced permanent changes, including personality alterations or Parkinsonian symptoms. Despite various theories, including links to influenza or enteroviruses, a definitive cause has yet to be established, leaving open the question of its potential recurrence.
