Mystery illness makes patient gouge own eyes out and turns children feral

A terrifying illness that dominated the world for an entire decade is still leaving doctors perplexed.

Half a million people lost their lives to the mysterious disease, which saw some patients undergo disturbing personality changes and become criminally impulsive.

The cause have never been confirmed, but 11 years after Encephalitis lethargica first appeared in 1916, it vanished just as suddenly as it had arrived. Since then, only a handful of cases have been recorded globally and many unanswered questions swirl around this strange epidemic.

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In the first phase of the disease - where around a third of sufferers would die - patients would fall into a constant state of sleep, but their minds would remain active the whole time. Those who survived this terrifying pretence of rest often experienced profound neurological changes, which could range from self-damaging behaviours to becoming frozen like statues, trapped within their bodies and institutionalised for a lifetime.

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Known as the 'sleep sickness', Encephalitis lethargica (EL) swept across borders between 1916 and 1917, infecting more than a million people, with estimates on the number of lives lost from the disease around 500,000. The disease could infect anyone, from children to older people.

At the start, it presented like many other common illnesses, with patients experiencing a sore throat, cough, or sometimes a fever. Then it would quickly take a turn for the worse, as double vision and extreme fatigue would take hold.

Once this fatigue took over, it could be terrifying, both for patients and those around them. People could become comatose for weeks, or even months. While they appeared to be asleep, disturbingly, sufferers were often completely awake inside their minds. With their brains as active as normal, they knew what was happening around them, but could not react, or move - trapped inside an agonising sleep.

The disease stumped the medical community when it first appeared. The wide range of symptoms - from this strange 'sleep' to profound behavioural or personality changes - left doctors struggling to treat patients who turned up at their doors requiring treatment.

It was a year after it first appeared when it was finally given the name of Encephalitis lethargica and designated as a new illness, by Dr. Constantin von Economo from the University of Vienna's Psychiatric-Neurological Clinic.

While it now had a name and official designation, that didn't mean the medics were any closer to getting many answers. They still had no idea what caused it, how to treat it, or how to stop the wave of the epidemic. By 1918, the Spanish Flu Pandemic was well underway, and wreaking havoc.

The timing of these two illnesses spreading far and wide meant doctors thought it was pretty likely that there could be a connection - particularly because for many patients, Encephalitis lethargica appeared after flu-like symptoms, indicating perhaps it was a post-viral issue.

Cases could roughly be split into three camps. The first third would, after the terrifying period of 'sleep', recover well, but another third would not survive this stage - usually dying due to respiratory complications.

Some autopsies were conducted on patients who died during the 'sleeping' phase of the illness, with the medical community desperate to find some answers, and these gave one of the first major clues about what was going on: at the base of the brain, a small part would be inflamed.

Finally, the last third of patients faced a lifetime of suffering. Having survived the 'sleep' stage, they would experience profound changes to their personality and behaviour - with those around them barely recognising them as the person who they had known before they slipped into an extended sleep.

At first, they would often become totally disinterested in the world around them, and find it difficult to concentrate - but things would only get worse.

Their brains would rapidly degenerate, and once the damage was done, there was no way for doctors to fix it. This was called post-encephalitic parkinsonism (PEP), and in young patients especially, meant decades of difficulty ahead.

Children who had Encephalitis lethargica would at first become intensely clingy, inconsiderate, and restless - leaving parents with a big job to manage their behaviour, but as they would go through puberty, things would become impossible.

"As they grew in strength, their incorrigible impulsiveness escalated in violence and they posed a danger to themselves and others," The Conversation reports. "Errant behaviours included cruelty to anyone who crossed them; destructiveness; lying; and self-mutilation including, in one example, removal of eyes.

"When they reached adolescence, these patients manifested inappropriate and excessive sexuality, including sexual assault without regard for age or gender."

Those who had Encephalitis lethargica still felt remorse, and when confronted with what they did wrong, would completely understand they should not have done it, but the disease had taken any shred of impulse control away from them.

Some would become career criminals - murdering, raping, and stealing - but it was hard to really define whether they could be responsible for what they had done, given the brain damage they had experienced.

The impulsive and criminal behaviour stopped for some patients, but only because the parkinsonism got so much worse, that it took away their ability to move altogether.

Much like the comatosed sleep endured in the first phase of the illness, sufferers saw their minds remain completely active, but trapped with a frozen body.

Stuck inside their bodies, all the things that make us human would slowly leave them. They couldn't recognise beauty or connect with art and had no sense of willpower. While they could see when someone else was in pain or suffering, they found themselves unable to feel sympathy.

With these essential parts of humanity stripped from them, their faces became like masks. As their muscles became totally rigid, rendering them unable to move, they would be unable to participate in society, and often spent decades inside institutions - despite the fact that in many ways, their minds were active as usual.

Tragically, doctors have never found a treatment with long-term success.

In 1927, more than a decade after it first appeared, the disease practically vanished. Since then, in the last 85 years, there have only ever been 80 recorded cases.

But that doesn't mean researchers are not looking for answers even to this day - with many studies indicating that encephalitis and this type of swelling of the brain, can be an autoimmune response or occur after a virus.

While mysteries swirl around the disease even a century later, the threat it poses still lingers. Until answers are found about how it took hold, it could always come back.