. >> reporter: a neurologist at the university of texas southwestern, dr. greenburg, has researched this rare illness for nearly a decade. and while the cdc has only been tracking cases since 2014, he knows it has been here longer. >> it's a life-changing event for the entire family. this turns worlds upside down. >> he's my buddy, you know? he's still my buddy, he ain't changed, but i know he just can't run up and hug me. that's what i miss the most. >> wow, that is so cool, buddy. >> reporter: we first met camden carr and his family in october 2018. >> i can do did. >> reporter: afm would devastate the 3-year-old's small body, leaving him severely paralyzed. unable to afford a home nursing aide, the brunt of camden's care has fallen on his parents, chris and brittany. >> medicate, switch his bed out and brittany. >> medicate, switch his bed out from a normal childhood b >> hey, daddy, daddy. >> what's wrong? >> i love you. >> i love you too, buddy. >> reporter: i know this is hard, chris, but how has afm changed your son? >> every way, shape or form you c