MOSELEY, Va. (CNN) Carter Roberts, 3, was the picture of health.
"Just the epitome of what any happy little kid should be," mom Robin Roberts said. "Just very charming little boy."
But then doctors from three different medical centers diagnosed Carter with acute flaccid myelitis or AFM. He was paralyzed below his neck by the polio-like illness.
"Those are his ashes," his mother said.
Carter passed away in September at the age of 5. And he's not the only child to succumb to AFM this year. At least one other, Alex Bustamante, 6, lost his battle with AFM in May.
Reporter: But the CDC says no AFM deaths in 2018.
Robin Roberts: That's not true.
Reporter: If you could be in a room with the director of the CDC, what would you say to him?
Chris Roberts/Carter's father: Just wake up and do your job. Tell us what you're hiding.
CNN asked Dr. Anne Schuchat, principal deputy director of the CDC, why the agency is reporting zero AFM deaths in 2018.
Reporter: These parents want to know why these deaths haven't been recognized by the CDC.
Dr. Anne Schuchat: The reporting of the diseases has a lot of steps... So, there may be a lag," Schuchat said. "We are working 24/7 to increase recognition, to get the reporting into the system... Every one of these episodes is difficult and the deaths are really tragic.
Reporter: The parents think the CDC is hiding something.
Dr. Anne Schuchat: OK, I'm so sorry to hear that... I'm just very committed on behalf of the agency to share what we know when we know it.
The CDC's own medical advisers on AFM who speak to CNN say the lag in reporting the deaths is too long and the turnaround should be faster.
Parents have also criticized how the agency has handled the outbreak. Carter's family worries how the CDC will learn from these deaths if they don't recognize them.
"I'd hate to think that... there would be another parent crying their eyes out because their child's in an urn," Robin Roberts said.
Now, they're left to remember their son who had just started kindergarten when he died.
"He was super smart," his mother said. "I think his backpack is probably the hardest thing to see."
Carter's parents hope his death will be recognized and make a difference.