NYT In its original form, the virus survives in just two countries. But a type linked to an oral vaccine used in other nations has already turned up in the West. Most American parents hardly give thought to polio beyond the instant their child is immunized against the disease. But there was a time in this country when polio paralyzed 20,000 people in a year, killing many of them.
Vaccines turned the tide against the virus. Over the past decade, there has been only one case in the United States, related to international travel.