The First International Conference on Emerging Infectious Diseases was held in Atlanta, Georgia, on 8 to 11 March 1998. It was organized by the Centers for Disease Control and Prevention with the sponsorship of the American Society for Microbiology. And this is just in the United States.
Infectious diseases remain the leading cause of death and morbidity on our planet.
Of course, war, famine, poverty, and neglect, which are so prevalent in human populations, are always the harbinger of infection and disease. Measles is derived from canine distemper, mycobacteria came from ungulates, diphtheria came from water buffalo, and so on. I believe that many of what we refer to as emerging diseases can be traced to subtle differences in human behavior and technology rather than to changes in bacterial populations. For example, the aerosolization of water in western society, ranging from the widespread use of showers instead of baths to the spraying of produce in supermarkets to air conditioning, has probably played a significant role in the emergence of Legionnaires disease and Mycobacterium avium infection in both normal and immunocompromised hosts. Legionella pneumophila is found widely in nature as an infectious agent of predatory protozoans.