Knut the Polar Bear’s necropsy results are in, and it seems that the famous 4 year old’s immediate cause of death was drowning. However, experts who examined Knut say that the underlying cause was an infection of the brain called encephalitis. According to Claudia Szentiks, the pathologist who led Knut’s examination:
“Given the massive scale of the inflammation, Knut would probably have died sooner or later.”
Knut was a polar bear who was born in captivity at the Berlin Zoological Garden. Rejected by his mother at birth, he was raised by zookeepers. He was the first polar bear cub to survive past infancy at the Berlin Zoo in more than 30 years. Although he was initially the subject of international controversy, he won the hearts of an adoring public, and became a tourist attraction and commercial success.
On March 19th, Knut collapsed and died in his enclosure, witnessed by 600 to 700 zoo visitors who reported that after the bear’s rear, left leg began shaking, he became agitated and began convulsing several times before falling backwards into the pool.
Encephalitis literally means an inflammation of the brain, but it usually refers to brain inflammation caused by a virus. Symptoms of encephalitis include sudden fever, headache, vomiting, heightened sensitivity to light, stiff neck and back, confusion and impaired judgment, drowsiness, weak muscles, a clumsy and unsteady gait, and irritability. Symptoms that might require emergency treatment include loss of consciousness, seizures, muscle weakness, or sudden severe dementia.
Viral encephalitis can be due either to the direct effects of an acute infection, or as one of the sequelae of a latent infection. A common cause of encephalitis in humans is herpes simplex virus type I (HSE) which may cause inflammation of the brain. This can result in death. Others include infection by Flaviviruses such as St. Louis encephalitis or West Nile virus, or Toga Viruses such as Eastern equine encephalitis (EEE), Western equine encephalitis (WEE) and Venezuelan equine encephalitis (VEE).
What is the prognosis?
The prognosis for encephalitis varies. Some cases are mild, short and relatively benign and individuals have full recovery. Other cases are severe, and permanent impairment or death is possible. The acute phase of encephalitis may last for 1 to 2 weeks, with gradual or sudden resolution of fever and neurological symptoms. Neurological symptoms may require many months before full recovery.