Giblin, when he wrote When Plague Strikes, was interested in seeing whether there was a pattern in the populace afflicted by the diseases he described. All these plagues, from the one which struck Athens to the AIDS pandemic in our time, were unexpected and found physicians helpless to understand or cure them. Appeals to God were equally ineffective, although priests and ministers insisted that the diseases must be willed by Him. This attitude prevailed among many different religious groups.

The threat posed by disease was invisible and there were no remedies available, so panic often arose. When residents of an afflicted area fled to where they hoped they might be safe, they usually spread the disease even further. Typically they also looked for culprits who might be responsible for the calamity. The Muslim inhabitants in the southern Ukraine, for instance, blamed the Black Death...