You never get sick — ever since you began running regularly three years ago, dropping 75 pounds and cutting out chips and desserts, you've been healthy as a horse — but suddenly, as the calendar flips to 2014, you have this monstrous cold. You get night sweats, fever; you can't shake it.

Eventually, you get better, so you decide to go for a five-mile run on Underhill's Irish Settlement Road near your home. Despite the cold, gray Sunday, you're happy to be outside again. But you feel unusually weak.

You won't forget this run; it's the last one you'll do for months. Because on Monday, January 6, the backache begins. It only gets worse the next day — and it's accompanied by a strange tingling in your toes.

By midweek, you're really losing power. You're so weak that you have to lean on your 7-year-old daughter's shoulder when standing up. By Friday, you're unable to use the bathroom on your own, hold a spoon to get food into your mouth, or walk without pushing a chair across the floor. Your wife has to help you do all that stuff, and she's becoming as terrified as you are. You call your doctor, who rushes you to the emergency room at Fletcher Allen Health Care. You remain there for five days, completely paralyzed.

Sound like a nightmare? It was — but this actually happened to Will Billings, a 45-year-old employee of Green Mountain Coffee and father of two. Happily, not only has he since recovered, but he's running half of the KeyBank Vermont City Marathon & Relay this Sunday.

What went so terribly wrong, and how did he get better? During a recent 10-mile run along the Burlington Bike Path with this reporter and his marathon partner, Joel White, Billings shares his story.

The paralysis, he reveals, was a side effect of Guillain-Barré syndrome, an immune disorder that attacks the central nervous system. It's rare, affecting just one in 100,000 people per year, and can be triggered by a viral or bacterial infection, or even a vaccination. As it happens, Billings had a flu shot right around the time he came down with that cold. He still isn't sure whether it was the infection or the shot that began shutting down his body.

Left undiagnosed, Guillain-Barré can cause permanent paralysis and death, but Billings was lucky enough to be seeing a doctor who had an epiphany in the middle of the night. "It was just like an episode of 'House,'" says Billings, referring to the television medical drama featuring a brilliant-but-surly diagnostician. On that Friday in January, he checked into Fletcher Allen's emergency room for a lumbar puncture to confirm the diagnosis.

"It's kind of a wimpy name, 'Guillain-Barré,'" Billings says. "But at first, it was a huge relief once we got into the hospital and got the diagnosis and knew that it wouldn't be fatal, because of my age and the fact that I was in decent physical shape."

Billings began undergoing a five-day treatment that would further knock down his immune system before he could start to recover. "I was still losing power," he recalls.

As his stalled body awaited its jump-start, his mind raced. Though Guillain-Barré is fatal in just 5 percent of cases, long-term side effects for survivors can include residual weakness, atrophy, and loss of strength and endurance. "I thought, What does this mean for me, my job, my family?" Billings says. "Do we move? How am I going to manage all the snow and all that? OK, I don't think I'm going to die, that's great news, but how long is it going to take me to fully recover, and will I fully recover?"

The smallest things became the most frustrating. "I couldn't even roll myself over in bed," says Billings. "I'm independent; I don't like to ask for help. To ring the nurse to help you roll over in bed is pretty humbling."

So was sharing a room with a 90-year-old stroke victim, and needing to be strapped in a crane-like device by a physical therapist to get out of bed. Unable to sleep, Billings was wiped out. His digestive system had shut down, leaving him with no appetite, and one of the few sensations he had was "excruciating back pain."

Making his stay somewhat more bearable were the visitors. Billings' 8-year-old daughter made a card for his elderly roommate, who had no visitors of his own. Also on hand were Billings' wife, parents and in-laws, and his running buddy White, who tried to keep his spirits up by joking about sponge baths.

Still. "The kids were obviously very scared, going into the room and seeing me hooked up to a thousand machines," remembers Billings, who also lost control of one side of his face. "When my wife saw that, she panicked, and my mom was really upset when she saw me."

Billings says he tried to be "as positive as possible about the process" — which included a high-dose immunoglobulin treatment delivered intravenously to speed recovery. He began to notice that he could move his right leg two inches, a small improvement that gave him hope.

After five days at Fletcher Allen, Billings was transferred to Fanny Allen, where he was told he would stay for two months of rehabilitation with a physical therapist and occupational therapist. "But I was showing daily progress, so I negotiated a way out after a week and a half," says Billings, who explained to his caregivers that he had "everything he needed to survive" on the main level of his Underhill home. He was discharged with a wheelchair and walker on January 25.

As the next month progressed, he was able to stand, and then walk, and then drive and even travel for business. But it wasn't until Billings went for a three-mile run on a sunny late February day that he felt somewhat normal again. "Running is an important part of my life, as it reduces stress, offers time alone to recharge my batteries and think creatively," he explains.

It's not unheard of for people with such illnesses to rebound from paralysis and return to their previous level of athletic activity, according to Massachusetts-based neurologist and Guillain-Barré authority Peter Lichtenfeld. "I had one patient who made it to the Wimbledon tennis tournament one year after illness," he says by phone, "and another who ran a full marathon two years after illness."

But racing 13.1 miles four months after being paralyzed is remarkable by any standards. Though Billings now admits to feeling stiff sometimes, and a bit apprehensive about a training regimen that has been less intense than usual — about 20 miles per week — he was determined to start setting running goals once he could put one foot in front of the other. In addition to this weekend's race, Billings has set his sights on July's Mad Marathon in Waitsfield, the New Balance Falmouth Road Race in Massachusetts in August and the Cape Cod Marathon in October.

But first up is the Vermont City Marathon. "It's one of the most popular and best-managed local events," Billings says. "While I've historically focused on [running] time, my goal this season is to finish strong and have a great time."

The original print version of this article was headlined "Road to Recovery"