More than a century ago, while the Spanish flu pandemic was killing millions around the world, a strange and disturbing disease emerged that swept Europe and left scientists baffled. This disease was known as Encephalitis lithurgia (EL), and its spread began in the winter of 1916, when the Austrian doctor Konstantin von Economou noticed the appearance of patients with strange neurological symptoms that had no resemblance to the diseases known at that time.
Patients initially suffered from flu-like symptoms, such as general weakness, slight fever, sore throat, headache, dizziness, vomiting and chills, before the symptoms developed into sudden and terrifying neurological manifestations. In some cases, patients died within just days, as in the case of a girl who was suddenly paralyzed while returning from a concert, only to lose consciousness and die after only 12 days.
Some forms of the disease, particularly somnolent-ophthalmoplegic encephalitis, were characterized by profound sleepiness, in which patients slept for long hours at a stretch, but were aware of their surroundings. The death rate in this form was high, exceeding 50%, yet some patients survived without any long-term effects. Physician Oliver Sacks described the patients he treated in New York in the 1960s as “conscious but not fully awake; they sit motionless and speechless all day, without energy, motivation, or desire, as if they were ghosts or zombies.”
As the disease developed and spread, other forms appeared, accompanied by hyperactivity, insomnia, and involuntary muscle movements involving the face, limbs, and sometimes the eye muscles. The chronic stage is characterized by manifestations similar to Parkinson’s disease, in addition to sleep, speech, and breathing disorders, and complex psychological problems. In the decades following the epidemic, some researchers estimated that half of Parkinson’s disease cases were the result of encephalitis lithargia.
The cause behind this mysterious disease is still unknown to this day. Some scientists linked it to the Spanish influenza pandemic, but later studies showed that the two diseases spread independently. A recent hypothesis is that the cause may be enterovirus, the type of virus that includes polio and is transmitted through bodily fluids. So far, there is no clear scientific consensus about the real cause.
By 1927, after nearly half a million people had died, the disease suddenly disappeared. Although this was good news for humanity, the mystery of the cause leaves open the possibility of a similar disease returning in the future. As one recent study concluded: “If the disease returns in the context of another pandemic, this will be an opportunity to use modern methods to identify and understand its cause, and perhaps prevent its recurrence.”
Encephalitis lithargia remains one of the most fascinating medical mysteries of the twentieth century: a fatal disease that appeared suddenly, baffled scientists with its strange symptoms, and became a vivid example that neurological diseases may hold secrets that are still unknown today.
date:2026-02-13 12:53:00
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