Infectious diseases such as cholera, plague, smallpox, yellow fever, rabies and exanthematic typhus used to plague our societies in the past. To some extent, modern, industrially developed countries like the western European ones, the US, Canada, Japan and Australia, have been liberated from these problems as some of the worst diseases have been eradicated. However, some new ones have developed in their place, such as HIV/AIDS, and it is obvious that, within the foreseeable future, the problem of how to handle such diseases will be with us, in western Europe, the US, Canada, Japan and Australia as elsewhere. And the liberal use of antibiotics has meant that some of the old diseases are returning in more sinister forms than ever.