Weekend Argus (Saturday Edition)
Riddle of Knut’s death finally solved
Autoimmune condition led to the death of iconic polar bear, writes STEVE CONNOR
HE APPEARED on the cover of Vanity Fair, became friends with Hollywood film stars and was a box-office sensation. Now scientists can write the final chapter in the story of Knut, the polar bear who drowned in his outdoor enclosure after an epileptic fit brought on by a mysterious disease.
Tests on his preserved brain reveal that the fouryear-old bear suffered from anti-NMDA receptor encephalitis, caused when his immune system attacked his own brain cells. This is the first time the autoimmune condition has been found outside humans.
Scientists said that the non-infectious condition probably had nothing to do with his captivity or the fact that he was hand-reared by a devoted zoo keeper after being abandoned by his mother in Berlin Zoo. Wild polar bears may also suffer the same brain disorder as Knut but just never get diagnosed, the researchers said.
“Until now, this disease has only been known in humans. In this illness, the body’s immune system overreacts and produces antibodies which damage nerve cells instead of fighting against pathogens,” said Harald Prüss of the Centre for Neurodegenerative Diseases in Berlin.
A study published in the journal Scientific Reports found that the autoimmune disease attacked the anti-NMDA receptors within Knut’s brain. The molecules are involved with the transmission of signals between nerve cells.
“Epileptic seizures, hallucinations and dementia are among the possible symptoms. In humans this is a disease that is relatively responsive to medical treatment,” Dr Prüss said.
Knut’s life was a modern fairy tale – or horror story – depending on your point of view. His first public appearances as a cute cub helped attendance figures at Berlin Zoo to soar by 30 percent.
The polar bear became so famous that celebrity photographer Annie Leibovitz was soon dispatched by Vanity Fair to take his picture, which was then superimposed next to a shot of actor and eco- warrior Leonardo DiCaprio standing on ice.
Knut’s fame spread far and wide, especially after an animal-rights activist suggested that it was cruel to raise a polar bear in captivity and that it would have been better to have allowed him to die – a suggestion that caused outrage among Knut’s many adoring fans.
Silver coins were minted in his honour in Germany and stamps bearing his image were printed as far afield as Azerbaijan. Plastic replicas of the bear, DVDs and assorted tat followed and he was deemed such a commercial success that one zoo attempted to sue another over who owned the commercial rights to Knut, whose name was registered as a trademark.
However, the short life of the polar bear ended when Knut suffered a fit in full view of several hundred zoo visitors on 19 March 2011, causing him to slide under the water of a pool in the outdoor enclosure that he shared with a handful of other polar bears at Berlin Zoo.
Although encephalitis was suspected, it is not until now that scientists have been able to confirm the precise type of autoimmune disease that caused the seizure. – The Independent