What’s happening at that zoo?
The boys at GGS where my wife works told her about this story they had heard; apparently some polar bears had acquire zebra herpes, and they wanted to know more! The idea of zebras and polar bears engaged in coitus (HA! I’m channeling Sheldon Cooper!) was too incredible to pass up, so I’ve done some rudimentary Google searching. A summary from Geek System tells the story, also detailed from Scientific American, from a primary research article published in Current Biology.
The Wuppertal, Germany Zoo has had at least 10 polar bears get sick with a mysterious viral infection over the past few years. One of the bears, Jerka died in June 2010 after suffering a series of seizures. Autopsy of the bear indicated severe inflammation of the brain caused by a virus. Molecular analysis of the virus from Jerka found that the virus infecting the bear was a combination of two other viruses of equine (zebra) origin, EHV9 and EHV1. The EHV1 virus is normally a respiratory virus, however EHV9 is known to cause encephalitis, however there is no evidence that either virus has ever been capable of crossing the species barrier. What appears to have happened is that these two zebra-restricted viruses have recombined to form a new virus that does not distinguish between species. Since the zebras and polar bears are separated by at least 200 feet of space, have never come into physical contact with each other, and do not share zookeepers, this suggests that an additional species such as mice or rats have been able to carry the virus between the two animal habitats.
This scenario does not particularly surprise me. Viruses have a great propensity for swapping genes back and forth, and the phenomenon of antigenic shift due to recombination is the mechanism behind the emergence of pandemic influenza outbreaks in human populations. A similar recombination of two viruses was behind the emergence of the pathogen in last year’s movie “Contagion.” The situation in the Wuppertal Zoo has to some extent provided the perfect situation for this to occur: there are a number of animal species from geographically diverse regions, all bringing assorted pathogens unique to them in close proximity. The confined spaces in zoos allow pathogens to easily spread between animals should one become infected, and the high level of traffic (zookeepers, incidental animals like mice, and the public) can permit easy transmission in a situation where you might think that the animals would be protected. The situation in Wuppertal was additionally exacerbated as several animals were asymptomatic for infection, which made clarifying the scope of the outbreak difficult.