17 August 2012 Last updated at 17:09

Zebra virus spreads to polar bears

Zoos are being warned to be on the lookout for deadly viruses that can jump between different animals.

A polar bear died at a zoo in Germany after it caught an illness from a zebra living nearby.

Viruses are normally spread between the same type of animal but some can jump between different species - making it harder to control.

An international team of researchers has been set up to work out how they are spread.

They are worried that killer illnesses like this could threaten endangered animals.

Jerka was twenty years old and sadly died from the virus

Another nine polar bears at the same zoo have been tested and many of them showed signs of the same infection.

The animals didn't have the same keepers so it's not likely to be spread via humans or by air.

One idea is that it could have been passed on by mice and rats running between cages.

Zoos bring together animals that wouldn't normally meet in the wild which makes it easier for different diseases to spread between them.