Maybe you have heard of the big EHEC case in Germany. Two EHEC strains have combined and formed a much more dangerous strain. Do you think that this strain will now threaten humanity "forever"? What I want to say is, whether the disease caused by this strain is established in the "disease world", from now on? Or will it disappear after removing the contaminated food? On what does it depend whether a certain disease is persisting in the human population?