Zebra virus kills polar bear in German zoo

Jerka died from a mystery brain virus

Zoos should be on the alert for viruses that can jump from one animal to another, threatening endangered species, say researchers.

The cause of an infection that killed a polar bear at a German zoo has been traced back to the zebra house, scientists report in Current Biology.

Two bears contracted the brain infection encephalitis, suffering seizures and frothing at the mouth.

One - a 20-year-old female, Jerka, died after little more than a week.

The other bear - a 16-year-old male, Lars, - was ill for several weeks but eventually recovered.

The team led by the Leibniz-Institute for Zoo and Wildlife Research (IZW) in Berlin extracted DNA and RNA from a brain sample of the dead bear to discover which of many possible viruses caused the illness.

Gene sequencing suggested the culprit was a strain of herpes virus normally found in zebras.

Viruses spreading to unexpected hosts may threaten the conservation mission of zoos, they warn.

Most pathogens are adapted to one host but some can leap the species barrier.

Flu, for example, is thought to have moved between pigs, birds and humans during its evolution.