Odd, my search turned up over 22,000 results on the same terms.
I didn't browse through all 22,000, but the first two pages were all about how easy it would be for polio to land in the U.S. again.
Which makes the newspaper stories I cited earlier even more puzzling.
Mumps, which isn't terribly easy to spread...we get outbreaks.
Measles, which is pretty easy to spread...we get outbreaks.
Polio, who knows? But all the outbreaks seem to be confined to developing countries right now. And have been for many years, in spite of the fact that the IPV vaccine which we currently use does not prevent carriage of the illness and the fact that vaccine coverage in the U.S. has had some ups and downs. Curious.