The death in 2010 of Jerka, a polar bear at a zoo in Germany, has been blamed on a herpes virus that originated in zebras.

By sequencing and analysing viral genetic material from Jerka (pictured) and other polar bears, Alex Greenwood at the Leibniz Institute for Zoo and Wildlife Research in Berlin and his team identified the polar bear virus as being similar to the zebra EHV1 herpes strain. However, the virus that was found in the polar bears was a recombinant strain, which could explain how it was able to jump between species. Rodents moving freely between enclosures containing zebras and polar bears might have acted as vehicles for the recombinant viruses.

Because not all the infected polar bears showed symptoms, the team warns that disease outbreaks in zoos ought to be monitored more carefully to track pathogen spread and to prevent other animals from suffering Jerka's fate.

Credit: B. SCHEER/ZOO WUPPERTAL

Curr. Biol. https://doi.org/10.1016/j.cub.2012.07.035 (2012)