Just wondering

Why don't kids in post-apocalyptic fiction get the measles? A few days ago I finished reading S. M. Stirling's Scourge of God. It's the fifth book in a series, all set in a universe where something really strange happened in 1998 that basically repealed the laws of physics. Electricity stopped working, even gunpowder lost its explosive force.

Naturally, the first book (Dies the Fire) was full of the typical OMG post-apocalyptic coping with disaster without modern technology scenarios: hordes of people dying from starvation, for example, and a few smart people realizing that staying in the middle of a city (Portland, Oregon) that no longer works is not a real good idea and doing the classic bugging out to the boondocks to hunker down until the worst of the chaos has ended. A few people keep their heads to the extent of liberating farm animals (draft horses, cattle) from a living history exhibit. Dies the Fire is obviously heavily influenced by classic science fiction, e.g., Lucifer's Hammer, along with an overt homage to LOTR, and contains the usual obligatory plot elements. There are scavengers who resort to cannibalism and eventually (as the series progresses) form bands referred to as "eaters," for example, and the classic clashes occurring between The Reluctant Ethical Hero and The Sadistic Power-Hungry Tyrant. Stirling ends up having the Reluctant Hero do just about everything except pull a sword from a stone before he and the Tyrant meet in battle.

But none of that is what has me wondering. I know the rules for post-apocalyptic fiction; Stirling follows them all as the series progresses, including channeling some Stephen King ala The Stand and having some unspecified preternatural Ultimate Evil hovering just off-stage and lusting for humanity's soul. He hits all his marks and does so quite deftly. The books are a good read, well-crafted and entertaining. I'm a little annoyed with Stirling for not making the last two books (The Sunrise Lands and Scourge of God) stand alone the way the first three (Dies the Fire, Meeting at Corvallis, and The Protector's War) were, but I enjoyed reading them.

No, what I want to know is why no one gets measles? Or mumps? Or polio? Or maybe even influenza? They started off with stashes of antibiotics, but vaccines never got mentioned. Why aren't women dying in childbirth or from childbed fever? The latest book is set 22 years past-Change; where are the infectious diseases, viral and bacterial? There's a lot of battling going on -- why aren't there a bunch of one-armed or one-legged veterans hobbling around because it was either amputate or lose a limb to gangrene? I want some germs in action, or I want an explanation of how they're managing to manufacture antibiotics using the equivalent of 16th century technology.

Oh well, maybe in the next book Stirling will have someone stumble across a cache of Georgia peanut butter, decide that despite over two decades of sitting in a warehouse it's still edible, and the series will get the bloody flux that's been missing so far.