“The lowest number of polio cases ever recorded in the world was 223. And 2013 was on track for an even lower number, on the road to complete eradication of the virus,” NPR’s “Shots” blog reports, adding, “But this was a year when polio pushed back. Hard.” The blog examines how “[t]he number of cases in both Afghanistan and Nigeria fell significantly,” but outbreaks plagued Pakistan, the Horn of Africa, and Syria. “So far, billions of dollars have been spent in the eradication drive. The expectation is that it will take billions more to stomp out the last few cases and ensure that polio doesn’t stage a comeback. The challenge now is to sustain the political will for such a massive global campaign all the way to the end,” the blog writes. The blog includes comments from WHO spokesperson Sona Bari; Michael Klag, dean of the Johns Hopkins School of Public Health; and William Muraskin, professor of urban studies at City University of New York. An audio version of the story from “Weekend Edition Sunday” also is available (Beaubien, 12/15).