What is AFM? Health officials, parents describe the rare virus

The number of cases of a rare polio-like virus are growing across the United States and six of those cases have been reported in Minnesota.

It's called Acute Flaccid Myelitis, or AFM, and it has left health officials puzzled.

"Physicians are on the lookout for the more common symptoms," said Dr. Angela Sinner, of Gillette Children's Hospital.

Muscle weakness, difficulty swallowing and facial drooping are all signs of the polio-like illness that's now showing up in hospitals.

"We didn't think anything was wrong until all of a sudden his neck froze up and he couldn't move his left arm," said James Hill.

For 7 year-old Quinton Hill of Lakeville, AFM has left him with paralysis in his left arm. Other patients have it much worse.

"Some children have persisting swallowing problems so they're still dealing with the complications of using a feeding tube. There's children who are so sick they have trouble breathing and need breathing support," Hill added.

At Gillette Children's Specialty Healthcare in St. Paul, physicians are treating some of the six Minnesota cases. Nationwide, 38 cases in 16 states have been reported and there is still no known cause.

"What we don't know is why these common cold symptoms, why in some individuals does it turn into AFM that's where the mystery lies," said Dr. Sinner.

The Center for Disease Control started tracking AFM in 2014 and in one study, it found about a quarter of patients had fully recovered and regained use of their muscles after one year.

At Gillette Hospital, they are hoping for even better results.

"There are cases of good recovery and good potential for good healing," said Sinner. "We're doing everything we can to keep the muscles healthy."

One case has also been confirmed in Wisconsin.