Smallpox, which killed nearly 300 million people in the twentieth century alone -- three times more than all the wars in this century -- has been eradicated ( 1, 2). The story of this most universally feared disease and of its elimination is the topic of this chapter. Yet one of the more interesting notes about this major accomplishment of mankind is that considerable opposition stood in the way of its conquest two hundred years ago, as well as in the recent past.
The story of smallpox is interwoven with the history of human migrations and wars, dramatically favoring one population or army over another. Smallpox actually changed the course of history by killing generals and kings or decimating their enemies.
The smallpox virus has no animal reservoir; its infection is limited to humans ( 3). Subclinical, or medically undetectable, infections are rare, if they occur at all. The typical course of smallpox is an acute disease that produces obvious and distinct skin lesions and after recovery leaves its well-defined fingerprints as clearly visible, distinctive pock marks, usually numerous, on the