Recently two polar bears at a Berlin zoo started foaming at the mouth and having seizures, one of them , Jerka died a week later, the other Lars, survived after several weeks of intensive treatment.
Post-mortem studies on the brain of the dead bear revealed encephalitis, swelling of the brain, caused by a virus found in zebras and it was concluded through further tests that the zebra virus was responsible for the polar bears death. Another virus had crossed the species barrier.
The zebra house at the zoo is 68ft from the polar bear enclosure and none of the keepers care for both groups of animals. None of the feeding apparatus is shared and the zoo has ruled out any other possible cross contamination. They have no idea how the virus got into the polar bears, particularly as none of the zebras at the zoo were suffering from the condition.
Zoos bring together animals from all over the world, animals that would never normally be in close proximity to each other, often they would not even be on the same continent as each other. It is extremely unlikely, in fact nigh on impossible that this would have happened in the wild.
I am not anti-zoo. They play an important role in animal conservation with breeding programmes that hopefully ensure that endangered animals survive in sufficient numbers to carry the species forward. What concerns me is that they have no idea on how Jerka contracted the disease, how it was transmitted to her, until the death of that polar bear they had no idea that the virus could affect polar bears.
With seals in New England recently being found to be a vector for the avian flu virus H3N8, and with so many diseases, such as Ebola, West Nile Virus, novel H1N1 swine flu, Hantavirus and many more zoonotic diseases crossing the species barrier from animal to man could it be that zoos and sanctuaries become the breeding ground for these viruses to jump from one species of animal to another, allowing them to mutate and adapt to their new host before they finally are able to jump the final barrier and cross into humans?
Prof Klaus Osterreider from the Free University Berlin said in an interview with Biology (journal)
“These viruses do not seem to respect boundaries, and in fact we do not know that they have any”
A sobering thought indeed.