SMALLPOX MUST BE unique in being an affliction that was eradicated by public-health measures before anybody found a way of curing it. The last victim was reported more than thirty years ago; not a single person anywhere has suffered from it since. Fresh epidemics of 'the spotted death', we are often reminded, could be started by terrorists; and, if their virus caches are more tangible than a certain dictator's weapons of mass destruction, humanity's respite from this scourge may soon be over.

Whether one prefers to marvel at the conquest of smallpox or to shiver in anticipation of a viral 9/11, it would be a good idea to read this book (or, better still, one of its major sources, Donald Hopkins's The Greatest Killer: Smallpox in History, first published in 1983 and