June 16, 2011 -- Former quarterback Danny Wuerffel has been diagnosed with Guillain-Barré syndrome, a rare autoimmune disorder that causes paralysis. Wuerffel, who lives in Decatur, Ga., noticed he was losing sensation in his legs and strength in his arms shortly after he battled a stomach virus June 4. It's thought that his immune system started to attack the nerves that control movement and sensation, mistaking them for the virus.

Wuerffel's strength is currently half of what it was, according to his wife, Jessica.

"He's hanging in there," said Jessica, who was taking their three young kids to the beach for a distraction. "It's a distressing situation but, to be honest, his faith is strong."

Guillain-Barré syndrome affects about one in 100,000 people, usually striking in the days or weeks following a viral infection, according to the National Institutes of Neurological Disorders and Stroke. Surgery and vaccinations can also trigger the disorder. But it's unclear why some people are affected while others are not.

"It's like a bolt of lightning that kind of comes out of the blue," said Dr. James Caress, associate professor of neurology at Wake Forest Baptist Medical Center in Winston Salem, N.C.

Most people with Guillain-Barré reach their weakest point within two to four weeks after symptoms first appear. In severe cases, the disorder can attack the nerves that control breathing muscles, such that patients need ventilators and feeding tubes to survive, Caress said.

Wuerffel is not completely paralyzed, but has been advised by his doctors to stay immobile during his recovery, his wife said. But it's unclear how long that recovery will take.

"The thing with Guillain-Barré is you can't really give a timeline," she said. "But knowing him and his competitive nature, he'll want his body to heal as fast as possible." Despite his immobility, Wuerffel can speak and has "good mental clarity."

Treatments for Guillain-Barré, such as plasma exchange and intravenous immunoglobulins, are aimed at ridding the body of the dangerous antibodies attacking the nerves and replacing them with healthy antibodies from donors. But while treatments can the accelerate recovery, they may not influence how weak the person gets before regaining his or her strength. And the unknown can be terrifying.

"I'm sure it's very scary for patients," Caress said. "We can start treatment immediately but we may not be able to stop that train from rolling."

Recovery time runs from a few weeks to a few years. But about 30 percent of patients still have some degree of weakness after three years, according to the National Institutes of Neurological Disorders and Stroke.

"Some people will also have persistent sensory symptoms," such as numbness or tingling, Caress said. "And even those who regain their strength may have lost some of their coordination."

Wuerffel, who won the Heisman Trophy in 1996 while playing for the Florida Gators, was drafted by the New Orleans Saints in 1997. He played for the Green Bay Packers, the Chicago Bears and the Washington Redskins before retiring from the National Football League in 2002. He now heads up Desire Street Ministries, a Christian charity that serves impoverished communities in New Orleans.

Faith has played a crucial role in Wuerffel's positive outlook following the scary diagnosis.

"Physically, the whole diagnosis is going to take a toll. But his spirit and his faith are very much intact and strong," said Barry Snyder, director of development for Desire Street Ministries. "We all go through physical struggles, and it's great to know that he's in God's hands while his body is not cooperating."