Doctors baffled by boy's mysterious illness

Landon Jones, a 12-year-old from Iowa, woke up one day with a mysterious illness. Although he can taste, swallow and digest food normally, his body no longer tells him when he's hungry or thirsty.

His parents have held off on sharing their story for the sake of his privacy, but now, desperate for answers, they're speaking out, reports CBS News medical contributor Dr. Holly Phillips.

"It's hard to explain," Landon's father Michael said. "You have a child who's running and playing and laughing and then you wake up one night and our world is flipped upside down."

It all began last fall just days after celebrating his 11th birthday. Landon woke up one morning with absolutely no urge to eat or drink. He was dizzy and severely congested.

A chest x-ray revealed a bacterial infection in his left lung, and although that eventually went away, Landon's ability to feel hungry or thirsty never returned.

"You can put food in front of him, he won't touch it," Michael said. "It'll sit there all day and all night."

Over the past year, the sixth grader has lost about 40 percent of his body weight, plummeting from 104 pounds to just 67.

The Jones' search for answers has taken them to five different cities including Rochester, Minnesota, where pediatric neurologist Marc Patterson examined Landon at the Mayo Clinic.

"This combination of loss of appetite and loss of thirst is something that I have not encountered before," he said.

Patterson believes the problem could lie within the boy's hypothalamus, the pea-sized portion of the brain that regulates hunger, thirst and essential functions like sleep and body temperature.

"Functions that are normally automatic for all of us have become voluntarily, or need to be voluntary in Landon's case," he said.

Because of his condition, Landon's parents have been presented with a unique challenge.

"The way we're seeing it as parents is that we're being his brain -- telling him to eat, and drink," Michael said. "We're being his hypothalamus."

Michael sits with Landon at every meal, encouraging him to eat and drink, his mother Debbie stocks their kitchen with healthy food as well as high calorie and protein snacks, hoping something will help Landon maintain his weight, and his health.

"Even on the boosts and the weight gainers, he still is continuing to lose weight," Debbie explained.

The illness has not only changed Landon's body, but also his personality, transforming him from chatty and energetic to lethargic and withdrawn.

"It's very frustrating as a mother," Debbie said. "I miss my little boy. I just miss Landon."

"We can't just sit back and watch our son deteriorate over time and that's what he's doing, he's deteriorating" Michael added. "I feel like because of his condition his childhood is being robbed. I want him healthy. That's it, I want him healthy."

Along with their doctors, the family has reached out to the National Institutes of Health, hoping Landon will be considered for evaluation.

The agency has an undiagnosed diseases division that accepts 50-100 cases each year.