A new polio-like illness has spread across 22 states so far this year, impacting children nationwide.
So far, the Centers for Disease Control and Prevention has confirmed 62 cases of acute flaccid myelitis and plans to investigate 65 more.
Roughly 90 percent of the cases so far have involved children, who suffer from muscle weakness or paralysis that impacts face, neck, back or limbs.
The symptoms appear about one week after the children start experiencing a fever or respiratory problems.
So far, viruses, environmental toxins and genetic disorders are all possible causes for the spike.
The CDC said the West Nile virus, adenoviruses, poliovirus and non-polio enteroviruses are also possible reasons why the illness has begun spreading.
The CDC says this is still a rare condition that affects less than one in 1 million people per year.
Serena Hill, a mother in Tennessee, told WRCB that her son, Spencer, experienced common cold problems before he struggled to move his arms and to walk.
Spencer received steroid infusions that helped free up the paralysis. In the last three weeks, he has improved his motor skills. He still has little movement in his fingers.
The CDC has no idea why there has been a spike in cases, though there have been similar spikes in 2014 and 2016, according to Fox News.
Since 2014, there have been 386 total cases, including the ones so far this year.
2014: 120 cases nationwide across 34 states.
2015: 22 cases nationwide across 17 states.
2016: 149 cases across 39 states, including Washington, D.C.
2017: 33 cases across 16 states.
"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. "Now is it going to be as widespread as that? Hopefully not. And that's why we have to keep our eye on this."