The interaction of man with viral agents was possibly a key factor shaping
human evolution, culture and civilization from its outset. Evidence of the
effect of disease, since the early stages of human speciation, through pre-
historical times to the present suggest that the types of viruses associate
d with man changed in time. As human populations progressed technologically
, they grew in numbers and density. As a consequence different viruses foun
d suitable conditions to thrive and establish long-lasting associations wit
h man. Although not all viral agents cause disease and some may in fact be
considered beneficial, the present situation of overpopulation, poverty and
ecological inbalance may have devastating effets on human progress. Recent
ly emerged diseases causing massive pandemics (eg., HIV-I and HCV, dengue,
etc.) are becoming formidable challenges, which may have a direct impact on
the fate of our species.