It all started with a strange and persistent feeling of weakness one day in September 2014.
As Craig Swanson — then 12 years old, now 16 — describes it, figuring out what was wrong took a few tries.
"We went to the doctor's office and they told me I'd be fine and sent us home," the Wayzata teen recalled. "Then the chiropractor, then the hospital."
His mom, Larey Swanson, remembered what followed: 10 terrifying days in the hospital when doctors were trying to figure out why Craig had lost mobility in his neck and right arm.
"Everything was so new back then," she said. "They just didn't know how far this might progress or if he would gain any function back."
What Craig had was an illness that now, four years later, is getting a lot more attention in Minnesota and nationwide as cases seem to be on the rise: acute flaccid myelitis, or AFM.
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• Earlier: Health officials warn about condition causing muscle weakness
According to the Centers for Disease Control and Prevention, the polio-like illness has stricken at least 62 children in 22 states, including seven in Minnesota this year.
AFM affects the nervous system — specifically the area of the spinal cord called gray matter, which causes the muscles and reflexes in the body to become weak; it can cause paralysis. While it can be treated, AFM has no vaccine or cure.
On Friday afternoon, on a rare day off from school, Craig Swanson and his mother were heading to a physical therapy appointment.
Craig is now down to just two to three sessions per week, but he's gone through hundreds of hours of physical therapy since he was diagnosed with AFM in 2014.
The fear at first was that the condition would eventually block Craig's ability to breathe — but with steroids and continued intensive physical therapy, Craig got to go home to keep working on maintaining his mobility.
Larey Swanson said she was in awe of her son's strength and determination to stop the illness from progressing and regain function in parts of his body. She also was struck by his compassion for others.
"I asked him what was the hardest thing about this, and he said, 'The hardest thing is to see you and Dad stressed the way you are' " — so that took my breath away," she said. "He still feels that and still feels he doesn't want families to struggle and be as anxious and scared as we were."
That's why Craig is channeling his experiences into a caringbridge.org page he set up just a week ago, where he's hoping to connect with other families living through AFM.
"I just thought it would be neat to see other people who have AFM and see if I could help them out," Craig said.
One of Craig's doctors, Mark Schleiss, serves as division director of pediatric infectious diseases at the University of Minnesota Medical School. He said there typically have been a handful of AFM cases across the country each year. But there have been more than 60 so far this year, according to the federal Centers for Disease Control and Prevention.
Schleiss said there have been noticeably more cases statewide in recent years; the Minnesota Department of Health first began surveillance of AFM in 2014.
Schleiss said the condition isn't new or mysterious, as some media reports have suggested. Like polio, diagnosis of AFM goes back decades or more, as scientists first began to understand how viruses affect the body. "The (AFM) viruses are genetically pretty similar to polio but different enough that the polio vaccine doesn't prevent them," Schleiss said. "They cause the same kind of disease in much, much smaller numbers."
Schleiss said there is no vaccine for AFM because partly because more research is needed to find the cause, and because the cost of creating and implementing a vaccine can be astronomical — perhaps ranging from $500 million to $1 billion.
Schleiss said it is plausible that a more widespread AFM outbreak could occur, as with any infectious disease.
"We've lived through this experience, whether it's Ebola in Africa, (or the) sudden appearance of Zika virus in Latin America, including some cases in the U.S.," he said.
While AFM cannot be reversed, Larey Swanson said she has already seen her son make extraordinary improvements.
Once told he would need to wear a neck brace for the rest of his life, things changed just a few months after Craig left the hospital.
"We ended up buying him a new one for Christmas because the one he was discharged with was kind of getting old," she said. "He took one look at the new one and said, 'No, thank you,' and he took the old one off and he has not worn a neck brace since that time."