There isn’t endemic polio in any countries neighboring Syria. Unless it was brought in from countries where it is endemic (possible if some of the combatants had carried it from Afghanistan or Pakistan; Nigeria seems more of a stretch), then the implication is that it’s lurking in populations, still being carried, waiting for vaccinations to lapse. There was an outbreak among the Amish in the US a few years back, and I doubt they brought it home from the Hajj. I suspect that actual eradication might take many decades of uninterrupted vaccination, and war anywhere lasting more than a few months is likely to result in outbreaks.
