There are now 62 confirmed reports of acute flaccid myelitis, or AFM, an illness similar to polio, across 22 states in the U.S., according to the Centers for Disease Control and Prevention.
As of Sept. 20, the CDC had confirmed 38 cases in 16 states, which aren't required to report AFM cases to the CDC.
This year's numbers are similar to 2016 and 2014. Since 2014, 386 cases have been confirmed, the CDC said on Tuesday. Currently, 127 patients are under investigation. The average age of those afflicted is 4, and 90 percent of those with AFM are 18 or younger.
"This remains a rare syndrome, but the similarities to poliomyelitis, polio-like illness, are concerning and bear close monitoring," Dr. Todd Ellerin, director of infectious diseases at South Shore Hospital in Weymouth, told ABC News in an interview. "Now is it going to be as widespread as that? Hopefully not. And that's why we have to keep our eye on this."