More than four years after Knut the polar bear suddenly suffered a seizure and drowned in his enclosure at the Berlin Zoo, scientists have finally figured out what was behind the celebrity bear's death.
At the time, an autopsy had determined that Knut the seizure was brought about via inflammation of the brain, according to CNN.
However it wasn't until Thursday when a study published in the journal Scientific Reports provided the answers that the world had so desperately craved.
According to the journal, Knut had anti-NMDA receptor encephalitis, an autoimmune disease discovered in 2007 that was thought to only affect humans. It is the most common noninfectious form of the disease, with symptoms that include headaches, nausea, hallucinations and other signs of psychosis.
Epileptic seizures can occur when the disease has progressed far enough - which is what happened to Knut.
Researchers at the Leibniz Institute for Zoo and Wildlife Research in Berlin were shocked by this discovery because they had searched for a pathogen responsible for the brain inflammation, but were forced to publish 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, was finally able to make the connection upon testing Knut's remains, after he read the report, noticed similarities between Knut and his patients and contacted Dr. Greenwood about his hypothesis.
"That was the answer," Dr. Greenwood said.
In light of this discovery, researchers hope to explore a previously undiscovered field of encphalitis and use that information to potentially save other animals in the future.
