|Oran, Algeria - the site of an outbreak of plague in the 1940s|
I guess the reason that it's a popular subject is because an epidemic disjoints society, in the same way that war can be a major bringer of change, a plague is out of the control of most people, and human reactions and emotions are laid bare. On the surface Camus' novel deals with a real-life outbreak of plague in Oran in Algeria in the 1940s. It's generally pretty factual, and evidently owes at least a little to the much earlier Defoe account. Both novels' preoccupation with the statistics of the plague reflect how little people fundamentally change in spite of living in different historical periods (a cause for optimism or pessimism depending on the individual).
However beneath the surface story Camus also used the plague and the conditions it imposed as an allegory for the Nazi invasion of France (Camus had been a dedicated Resistant); and the allegory becomes more obvious as the novel progresses. Here we see the profiteers, those who in effect collaborate with the plague / the Nazis by choosing the path of non-resistance, and Dr. Rieux (the hero of the story) and others who fight to the end even when it seems pretty pointless.
I just thought this novel was completely stunning. Camus is great at creating a living breathing background, but he's also masterful at delving into his characters' hearts. I loved this book. It has a filmic quality to it, beautifully written, unflinchingly honest, it's wonderful. Camus richly deserved his Nobel prize, I just wish that he'd lived longer to write more.