A year and a half ago “Full Measure” first reported on a baffling new illness responsible for nightmarish scenarios: a child wakes up and his legs don’t move. Soon, he’s paralyzed from the neck down.

Since then, the number of cases has grown. Yet the Centers for Disease Control and Prevention says it still has no clue what’s causing it—and won’t say much else. One thing we know … the disease mimics one of the world’s most feared illnesses: polio. Today, we continue our investigation into the mysterious outbreak that’s left hundreds of American children suddenly frozen.

The following is Sharyl Attkisson’s “Full Measure” report on this issue.

Christopher Roberts, parent: Carter probably developed the flu-like symptoms on a Saturday morning and within 24 hours of that on Sunday morning we found him on the floor and no mobility on his right side. He was unable to move and he was faintly asking for help.

Carter Roberts was just 3 when he was hit by sudden paralysis that looked just like polio. We first caught up with father, Chris, last year at Kennedy Krieger Institute in Baltimore, Maryland, where Carter was hospitalized for months.

Roberts: Last night he cried for 25 minutes. Just uncontrollably. He’s in, I think, regular and constant pain. Although he is immobile, he can definitely feel everything all over his body. But then this morning we’ve had a really good day.

CDC gave the mysterious paralysis a new name: acute flaccid myelitis, or AFM. Myelitis is inflammation of the spinal cord. Doctors told Hayden Werdal of Bremerton, Washington, that he just had a sinus infection—but in 10 days he was paralyzed from the neck down. Mandy Baker was a musical honor student about to start her sophomore year of high school and went from feeling fine to being paralyzed in a single day. Her illness ran up a $3 million hospital bill and treatments not covered by insurance.

As cases piled up in fall of 2014, doctors theorized they were connected to a rare outbreak of a virus called enterovirus, or EV-D68. Unusually high numbers of kids were showing up at ERs with severe breathing problems from EV-D68. Some ended up paralyzed. Within five months, there were more than a thousand (1,153) severe cases of EV-D68 in 49 states, and at least 14 deaths. And 120 known cases of AFM paralysis in 34 states, mostly young children.

The CDC—normally quick to raise alarms and speak on TV when there’s any threat of infectious disease—wasn’t saying much at all this time. They declined our repeated interview requests and instead pointed me to this video that it provided WebMD.

Brian Rha, medical epidemiologist, CDC: Infants, children, and teenagers are more likely to become infected with enteroviruses and become ill.

The video offered little insight. I requested information under the Freedom of Information Act. It took CDC more than a year and a half to begin turning over documents. Internal emails show CDC investigated what could be triggering the AFM paralysis in some kids, including West Nile Virus, insecticides, international travel, and vaccines—particularly oral polio vaccine.

Officials say they still can’t pinpoint the origin. There was one physician in the email exchanges who treated dozens of the paralyzed children—and seemed to be looking at the bigger picture.

Dr. Benjamin Greenberg wondered if we were seeing the 21st-century version of polio … if it is “in the early stages of evolution,” he urged CDC, “we can get ahead of it.”

I recently tracked down Greenberg at Children’s Medical Center in Dallas.

Sharyl Attkisson: What’s the difference between what we’re seeing with these children and polio?

Benjamin Greenberg: Not much—which is interesting.

Greenberg filled in a lot of blanks on the mysterious afflictions … where the CDC would not.

Attkisson: Is it accurate to say this is less contagious than polio?

Greenberg: We don’t know yet. Part of what we’re lacking is the ability to go through a population, and determine who has been exposed to this virus and who hasn’t. We looked at the papers written 100 years ago describing cases of poliomyelitis in the U.S., and we talked to colleagues from around the world who are actually part of teams who treat polio cases. And to all of our surprises, basically what we were seeing was a polio-like illness but not from the polio virus.

Attkisson: Millions of people had been infected with this EV-D68, but a relatively few actually come down with the paralysis. Do we have any idea why those certain children get paralyzed?

Greenberg: We don’t know that yet, but it’s worth noting that that phenomenon, that the same virus can infect thousands, hundreds of thousands, or even millions of people with only a few individuals having catastrophic events from the virus is true for almost every virus in human biology.

At its worst, polio killed 3,000 (3,145) and paralyzed 21,000 Americans (21,269) in a single year back in 1952. In 2014, there were 120 known cases of AFM paralysis in the U.S. In 2015, there were just 21. But last year, the number surged to 138. There have been five confirmed cases so far this year.

Attkisson: Did polio have a pathology that was anything similar to what you’re seeing now?

Greenberg: So if we look at the history of polio, at least in the United States, it started with small outbreaks, and then would disappear for years, and then re-emerge.

Attkisson: Clearly, it’s not a one-time event.

Greenberg: Clearly, as we saw in this last year, we see—we had a spike in cases again. There were about 120 reported in 2014; relative to—monitoring that started in August. In 2016, what we saw is over 130, maybe over 140, cases. And so we know that this virus has the capability, if it is the cause, to come back, and to cause damage.

With CDC saying so little publicly, families struck by the horrible illness have found each other on Facebook. Erin Olivera runs a parent support group. In 2012, she says she noticed her 2-year-old son Lucian crawling oddly; soon he could barely move. In Albany, Oregon, McKenzie Anderson went from having a cold to being paralyzed from the neck down and on a ventilator in 12 days. There’s Sadie Briggs in Oklahoma City, Laura Carton of Oswego, Illinois, and Adrian Dittmar of Seaman, Ohio.

And although CDC told me it has “not received any reports of death in an AFM case…”

The family of 14-year-old Isaac Prestridge of Louisiana says the CDC confirmed to the coroner that AFM was the cause of their son’s death. He got sick last October, complaining of a “weird feeling in his knees,” and died two days later.

Attkisson: Some of these kids die?

Greenberg: “They do. It is—it is a very rare event—to have death related to acute flaccid myelitis; unfortunately, it has happened.”

Attkisson: As a medical outsider, I look and I say more kids have been hurt seriously with this than measles, Ebola, and Zika combined. But you don’t hear anything about it. There’s no emergency funding requests, CDC is not making big public pronouncements. How do you explain that?

Greenberg: So there are some scientist reasons to have priorities around Ebola, measles, and Zika that are very valid. Enterovirus D68 is a common virus with a low rate of causing—significant paralysis or conditions that lead to disability. And so the decisions have been made that, while it is a problem, while it is a concern, it may not garner the level of need that some other public health issues do.

Attkisson: Do you agree with that?

Greenberg: I wish we had the resources to do it all.

Greenberg says there’s reason to hope that AFM isn’t the beginning of another polio. So far, he says, the rate of paralysis after infection seems lower.

Greenberg: The No. 1 question we get asked is about rehabilitation and recovery. Will children get better after the event?

Attkisson: And what’s the answer?

Greenberg: They do. It’s very slow, and it takes a lot of work. When we stay aggressive and we push and we stay with a routine, we’re seeing slowly but surely improvements occur.

Today, Carter is out of the hospital and back at home in Richmond, Virginia. There’s been no improvement in his condition, but he’s considered “stable.”

Roberts: I guess long-term prognosis has varied greatly between the different patients to this point. What I’ve seen, what I’ve read and heard, there have only been two children who have recovered from this, but even then not fully because they’re still demonstrating muscular weaknesses.

Believe it or not, AFM paralysis isn’t a “reportable disease” like West Nile Virus or measles … meaning doctors aren’t required to report cases. Greenberg thinks that should change … in fact, he advocates a broadened surveillance system to track all kinds of sudden paralysis to better find answers as to what’s causing them. (For more from the author of “This Mystery Virus Is Being Compared to One of the World’s Worst Illnesses” please click HERE)

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