This course will explore the basic interactions between microorganisms and the human hosts they attack. Although these interactions are usually termed "infectious" they do not all turn out to be lethal or devastating for the hosts. In some cases infections are required for the normal development of the human digestive or immune systems.  In other cases, a long term relationship is established in which the host  and the infectious agent survive even though the latter can be one of the most dangerous disease producing organisms  (a pathogen) known to mankind (Tuberculosis). Nevertheless, the fact that microorganisms do cause many deadly diseases including those historic plagues that have caused untold  suffering throughout history such as Bubonic Plague, Smallpox, Cholera, and Typhoid fever, it is essential to understand the concepts and terminology of the causation of infectious diseases. Such an understanding will also permit the student to develop the capability to comprehend reports about disease outbreaks in the media, and to ask (hopefully) intelligent questions about their origin and importance. Topics will include a brief overview of Genetics so that pathogenicity can be understood more readily.  Also included will be analyses of why we are suddenly being confronted with emerging (completely unknown) and reemerging (those heretofore conquered) diseases, as well as a number of case histories that will bring out many aspects of what are termed the "common" characteristics of all pathogens. Finally, the critically vital topic of Bioterrorism will be discussed to elucidate of what we should or should not be afraid, and how to cope with the possible use of Bioweapons.