More than 2 million people have multiple sclerosis worldwide -- and that's just the ones who know it.
The disease is tough to diagnose, but thanks to new treatments, it's highly treatable.
Shirl Hartson has been living with multiple sclerosis since college.
"It was my first year of college. I was having problems falling and I was seeing double," she said.
The 49-year-old Waterloo woman takes a positive approach to a disease that's limited her vision and mobility over the years.
"I say to myself all the time that I can handle this," she said. "God will never give me anything that I can't handle."
Gael Yonnet at Covenant Medical Center is a physiatrist -- meaning he specializes in rehabilitation and movement, issues MS patients can face.
"There used to be a time when we couldn't really do anything about MS," Yonnet said. "Within 15 years of diagnosis, people were wheelchair-bound, unable to walk."
But things have changed dramatically.
"We've had very good therapy since the mid-90s," he said. "Patients overall are doing a lot better from a functional standpoint."
New treatments have made tailoring plans easier for a disease like MS that impacts every patient differently.
"After my training in spinal cord injury, I sought further training exclusively in multiple sclerosis," Yonnet said.
The vast majority of MS patients lead productive, normal lives -- but not everyone.
"I'm one person, but there's no two people with MS who turn out the same," Hartson said.