Who Killed Knut The Polar Bear? An Auto immune Disease Thought To Kill Only Humans

The celebrity bear, Knut, died four years ago, and no one has known why. Suddenly, he got a seizure and drowned in his enclosure at the Berlin Zoo.

But it is only now that scientists have found out how it happened.

An autopsy had been conducted at the time. It showed that the seizure on Knut was due to inflammation of the brain, according to CNN.

A recent study in the journal Scientific Reports gave the explanation. The journal showed that Knut had anti-NMDA receptor encephalitis, an autoimmune disease discovered in 2007 that was not known to infect non-humans. Being the "most common noninfectious form of the disease", it's symptoms include "headaches, nausea, hallucinations and other signs of psychosis".

If the infection increases, the patient can suffer epileptic seizures. Knut too suffered from it.

The Leibniz Institute for Zoo and Wildlife Research scientists had searched for a pathogen that led to the inflammation of the brain. However, they published the inconclusive results in 2014, according to the New York Times.

"We basically did the most intensive search for pathogens in a wild animal that's probably ever been done," said Alex Greenwood, the institute's head of wildlife diseases.

Dr. Harald Prüss, a neurologist and researcher at the German Center for Neurodegenerative Diseases in Berlin, finally tested Knut's remains, understood the underlying similarities between Knut and his patients and then talked to Dr. Greenwood about his theory.

"That was the answer," Dr. Greenwood said, according to hngn.

Scientists hope that they can explore the encephalitis field and apply them to future animals.