Judy Woodruff:

For the past few years, a mysterious polio-like illness has been paralyzing children in the United States, often striking after a mild illness, peaking every other year, and reaching record highs in 2018.

It's called acute flaccid myelitis, or AFM. While it's extremely rare, cases were reported in 39 states last year. But doctors and researchers say they still don't know what causes it or how to stop it.

Amna is back with that story for our weekly segment on the Leading Edge of science, technology and medicine.