Your text discusses Paul Ewald's studies of how evolutionary trade-offs might have influenced the evolution of virulence in human pathogens.One thing your text did not mention is disease caused by food-borne pathogens such as Salmonella,Campylobacter,and Escherichia coli O157:H7.In industrialized nations,fresh food is often shipped in bulk quantities for thousands of miles from where it is grown.This means that food-borne outbreaks can sicken large numbers of people,and also may force the costly recall of large amounts of contaminated food,over wide regions.This is a relatively recent development; for almost all of human history,fresh food had to be eaten close to where it was produced.Apply Ewald's ideas to food-borne diseases.Can we make any predictions of future trends in virulence? Are there steps we can take,specifically based on evolutionary biology,to decrease the incidence and severity of food-borne disease?