IntroductionThe virus responsible for smallpox—a tiny creature
known as variola—has been a despised enemy of civilizations
around the world. Over a period of at least three millennia it
was second to none in inflicting human pain, suffering, and
death. By some estimates, smallpox killed as many as 500 million
people during the twentieth century alone, and as recently as
thirty years ago, it was still at large in over thirty
countries, attacking some fifteen million people annually and
killing two million of them. Through history, we have battled
this foe with incantations, poultices, quarantines, and
vaccinations. After struggling to contain it, we have at last
conquered the disease globally and placed the last acknowledged
vestiges of the virus in high-security confinement. Now, under
the auspices of the United Nations, humans may be about to take
a final, irreversible, step: to exterminate the last remaining
captive samples of the smallpox virus. Thus, a quarter century
after smallpox as a disease was wiped