Infectious agents have been in existence since long before humanity, and despite the rapid advances characterizing the previous century in terms of the recognition and treatment of the diseases induced by these agents, infection remains a major cause of human morbidity and mortality, and a threat around which all our efforts appears faded.Hippocrates was the first to regard such diseases as a natural, rather than a supernatural phenomenon, encouraging doctors to look at physical causes of illness and to use objective observation and critical deductive reasoning. In those times infectious...