At the threshold of the third millennium, the human race is more vulnerable to mass epidemics than at any other time in history. Cases of bird flu, MRSA, influenza, and bioterrorism have never been higher. Differences in travel and social behavior spread infections more widely, and some infectious agents--including tuberculosis and HIV--are becoming resistant to nearly all available antibiotics. With changes in climate, diseases are either being described for the first time or even appearing in previously unaffected areas. Encompassing these rapid developments, this study presents the radical theory that humans are themselves a form of epidemic. Humans have been shaped by the effects of disease and are physically composed of an amalgamation of infectious tissue. Most alarmingly of all, it shows that the human race is the most destructive epidemic on the face of the planet.