I rather doubt that we in the U.S. would be any more or better prepared for the rash disaster than any other nation. We tend to be arrogant, and assume that we'll handle most any situation better than the rest of the world, but in general I think that's mostly hogwash.
Urban areas would, of course, be worse than decimated. Those who didn't get turned into trolls, beasts, and giants would be killed by them. One assumes that at least some of them would be intelligent enough to camp the supermarkets and other food source sites. Also, with the power / water / sewage infrastructure gone, it'd be difficult to find water and hiding places would be...obvious to sensitive noses, unless extremely well camouflaged as to scent. Which is, frankly, not something someone in the modern world really thinks all that much about.
Small towns and villages wouldn't be much better off, if at all so.
There would, of course, be a lot of dead feral cats, however, even despite their immunity: Most or all other mammals would be infected and transformed or dead. Yes, there'd be birds, but the impact of the ferals (and the domestics which have enough of a clue to actually survive without humans) upon it would be pretty devastating as well.
As to things in rural areas, and the survivalists: Most livestock would fall victim to the plague, if not all of it. That would leave crops, but it'd be extremely dangerous to farm, and trying to keep the fields safe and disinfected would be hellishly difficult. One of the things that the 'known world' in this story has going for it is that, generally, the sites with survivors are small and reasonably difficult for trolls, beasts, and giants to get to. There might be islands in the U.S. (I'm thinking of Drummond Island, Bois Blanc Island, and Mackinac Island, in the Great Lakes.) which retain some uninfected human population, but life would be extremely primitive, there. And, of course, the survivalist compounds aren't, generally speaking, designed nor prepared for this sort of a catastrophe. They're designed for economic and / or governmental collapse. All the guns and razor wire in the world aren't going to prevent the trolls and giants from visiting for very long. Guns don't necessarily work against them, very well, and ammunition's going to run out without a ready source of gunpowder, even with reloading. The challenges, just to keep people safe, fed, and uninfected, would be immense. And survivalists aren't known to be the cooperative type.
Finally, the whole nuke-fest, as described above, is pretty much a non-starter, save in video game terms. Even granted that the missiles, silos, and computers would still be working after not being maintained for ninety years, triggering the whole thing off would result in a 'Nuclear Winter' scenario, which would likely kill-off whatever uninfected life had managed to survive. I don't even want to think about the problems from fallout, alone, much less the climatological effect of the soot, smoke, and dust this scenario would launch into the stratosphere. We're talking about ice-age analog climatological changes, here, which would happen extremely rapidly. More rapidly than anyone would be able to prepare for.