Although ASF cannot replicate outside of a cell, it can survive for long periods of time without a host, which is why it’s particularly difficult to control. The virus is hard to kill, withstanding harsh environments, extreme weather conditions, and even persisting in meat that’s been cooked or smoked. That means when contaminated food scraps end up in swill, cannibalistic swine contract ASF. The contagion can lay dormant in exported corn or grain-based feed, too, until a hungry pig reanimates the virus, sometimes on the other side of the globe. The virus is also variable, meaning different strains of ASF are emerging in different areas of the world. And because the pathogen has a gigantic genome that easily changes to fit new conditions, veterinarians don’t have a vaccine against it.