Researchers at Johns Hopkins Medical Institutions have identified a virus that has killed almost a dozen Asian elephants in North American zoos. The source is a previously unknown form of herpes virus that apparently jumped from African elephants to the Asian species. Dr Gary Hayward, co-author of the research published in the journal Science, pointed out that the Asians are an endangered elephant species and that there may be "carrier African elephants" in zoos. If diagnosed quickly however the animals can be successfully treated with the antiviral drug famciclovir. Research on wild African elephant populations showed that the virus was present but did not tend to kill.