It was the virus that had parents in a panic.
Enterovirus D68 made headlines last fall when it sickened more than a thousand kids, killed a dozen and was suspected of leaving some paralyzed.
Then the virus seemed to just disappear. But did it really?
Researchers have spent the past year trying to determine how serious enterovirus D68 really is and whether it was truly to blame for those cases of paralysis.
Ella Frech of Dallas, Texas, is one of the children who caught a virus, then suddenly developed paralysis. Doctors believe enterovirus D68 may have been to blame.
The Frech family says they cried a lot, then decided to carry on.
She's not disabled. She can do everything that she did before, she just does it differently," said Rebecca Frech, Ella's mother.
"It was time to get up and do stuff. I was bored," said Ella Frech.
But more than a year after the first cases of enterovirus D68 starting popping up in children -- the mystery remains.
"There's been much work done over the past year since last year's illness season to understand was there a causation or was it simply a coincidence?" said Dr. Marie Lozon, chief of pediatric emergency medicine at the University of Michigan's C.S. Mott Children's Hospital in Ann Arbor, Mich.
Lozon cared for many of the Michigan children sickened by enterovirus D68 last year.
"Very, very sick with breathing problems, low oxygen, maybe even had to be put on a breathing machine or even be put on a heart lung machine to keep them alive," said Lozon.
Several children also developed paralysis.
"We don't know if enterovirus D68 was a direct cause," said Lozon. "The fact that we were seeing this soon after the enterovirus illness made us worry that there was a connection. Enterovirus is in the same family as polio. It is not polio, but it's in that family."
Enterovirus D68 was first identified in 1962, but last year was the first major outbreak. It's thought young children were vulnerable because their immune systems had never been exposed to this particular virus.
"It just seemed to hit the kids of Southeast Michigan pretty darn hard," said Lozon. "It was a very serious serious epidemic last year."
Enterovirus D68 isn't making headlines anymore, but Lozon says it may still be a risk. The hospital is waiting for test results to see if some of the children they've treated this year are suffering from the virus.
"The kids we're seeing that are getting sick enough to go to the ICU, to be admitted to the hospital, they look very much like those kids from last year," said Lozon. "We're seeing lots of those kids, but no where near the numbers we saw last year."
That may be because so many children were exposed last year and developed some immunity.
The steps to reduce the risk of catching enterovirus D68 are the same as those recommended to avoid other viruses.
"Covering your cough, cough hygiene, and handwashing," said Lozon. "And don't send your child to daycare or school when they're ill."
Fortunately, doctors at Mott have not seen any of this year's possible cases develop paralysis.
According to the Centers for Disease Control and Prevention, only two of the children last year who suffered paralysis or muscle weakness made a full recovery, but about two-thirds improved significantly.
Canadian researchers recently determined enterovirus D68 was no more deadly to children than more common viruses, but the children who caught it were more likely to suffer serious breathing problems. The CDC is still investigating that potential link to the cases of paralysis.
Frech needs a wheelchair, but she is determined not to let it slow her down.
"Every time I caught them pitying me or something, I always just popped a really big wheelie," said Frech.
She has traded ballet for wheelchair motocross, where she's fearless.
"I guess I'm trying to say that yeah, I'm in a wheel chair, yeah, my legs don't work, but I can still have a life, a normal life, like everyone else," said Frech. "Don't sit there and feel bad for yourself. Get up and play."
Ella's mother says they don't use the word "disabled."
"We prefer the term 'adaptive' because we feel like it's a better representation of what their lives actually look like," said Rebecca Frech.
To learn more about enterovirus D68, click here.