Presently the fireworms emerged from underneath the land. They ringed me on all sides, approaching slowly. I knew I should be scared, but oddly I wasn't. I was a mere three years old or thereabouts. My curiosity was insatiable.A fairly standard post-apocalyptic landscape, with fireworms inhabiting the desertified what is currently the southwestern USA; our hero, Daystar, and his girlfriend, Shadow, have more serious problems with the Christian cultists who want them dead, mainly because they are autistic. This interesting premise is executed in the usual way, not particularly bad but not particularly memorable either. Not too difficult to get hold of, if you want.
I got it because it featured in this survey of sf books featuring autism, but it was the sf book that had lingered longest unread on my shelves. Next in that list is The Universe Between by Alan Nourse.