It wasn’t bacteria or a virus that plagued young Michael Mendy’s body and mind. He did not inherit his symptoms from his mother or father. Nothing toxic was in his blood.

And while he was sick, Michael’s parents had no explanation.

“I had to figure it out. I had to find an answer. I had to find a doctor that could help him,” said Michael’s mother, Kathleen Mendy, who lives in western Cary. “You don’t think you’re going to come across something that nobody’s ever seen.”

But they had. Dozens of specialists and three years of suffering brought no diagnosis. Michael died a year ago, at age 16. And only then did the explanation and the terrible significance of his case emerge.

Doctors estimate that fewer than one in 100 million young people will share Michael’s journey. The sports nut and East Cary Middle School student was killed by a disease that mostly afflicts the elderly.

Michael was a heart-wrenching outlier, apparently among the youngest ever to suffer a spontaneous ravaging of the brain.

The onset

Kathleen Mendy thinks it started on Michael’s 13th birthday in 2009.

On that January day, another boy knocked Michael’s head to the court during a basketball game. He was playing again a minute later, his mother watching with a tinge of worry.

The symptoms of a years-long illness crept in that weekend, during a mother-son Super Bowl trip to Florida. That’s where she first saw Michael’s confusion, his unsure movements and his inexplicable crying.

It seemed at first like the troubling wake of the teen’s second concussion in three months, but that theory would erode and change. Across the next three years, in a nightmare that kept unfolding, the brawny teenager would drop almost half his body weight, spend months in the hospital, lose his speech and lay debilitated by simple infections.

The printed record of Michael’s hospital visits and test appointments is three and a half pages long. It documents an increasingly desperate search, listing 140 days in the hospital, 91 visits with doctors and 426 therapy appointments from 2009 to 2012.

“I always thought he would get better,” Kathleen Mendy said. “I used to always tell him, ‘Michael, one day you’re just going to run out of your bedroom, and you’re going to come running downstairs, and you’re going to be all better.’ ”

The turning point wouldn’t come.

While his friends went on to high school, Michael was confined to a wheelchair and fed through a tube. His care grew so intense that his mother brought on a full-time medical aide.

His father, divorced from his mother, drove in from Florida each time he entered the hospital, and Kathleen Mendy’s family often visited from New York.

Each treatment was more esoteric than the last. By the end of 2011, the Mendys had seen more than 30 doctors, medical specialists, faith healers and alternative practitioners.

“I tried chiropractors, reflexology, myofacial therapy,” Kathleen Mendy said. “I tried everything.”

‘I’m so glad I didn’t know’

The realization came to Kathleen Mendy on the last night of January 2012, the 22nd day that Michael spent in a UNC hospital bed.

He’d been kept alive in an intensive-care unit by a breathing machine while an infection took hold of his lungs. The mysterious disorder had left his body unable to respond.

The memory shakes Kathleen Mendy to tears. The scene sticks in her mind.

“Not until the night before he died, is when, honestly, it hit me,” she recalled.

The doctors laid a choice before his parents that night. Michael could go home with a tracheotomy and a ventilator, but they believed he’d live just a few months longer. Or doctors could remove him from life support.

Michael’s parents didn’t want him to suffer anymore. He died on Feb. 1, 2012.

Only months later would Michael’s family learn the reason for his degradation and death. An autopsy showed that the teenager died of sporadic fatal insomnia, a subtype of Creutzfeldt-Jakob Disease.

“I’m so glad I didn’t know what it was” before Michael died, Kathleen Mendy said. “Because then I wouldn’t have had hope.”

‘A descent into hell’

“This disease is a descent into hell,” said Florence Kranitz, president of The Creutzfeldt-Jakob Disease Foundation in New York City.

She saw her own husband die in 2001 of an ailment similar to Michael’s. Since then she has heard the stories of many of the 300 CJD victims her organization identifies each year, including cases of fatal insomnia.

“We get this phone call, and tragically it’s the same phone call over and over again,” Kranitz said. “They’ve never heard of this disease.”

The story she heard from Kathleen Mendy fit the profile, with one beguiling exception. Almost everyone afflicted by CJD subtypes are older than 45, except those who contract a variant of the disease genetically or through contaminated beef, which Michael had not.

Michael’s case quickly drew the attention of national experts, including Pierluigi Gambetti, director of the National Prion Disease Pathology Surveillance Center in Ohio. Gambetti, a pioneering researcher, examined Michael’s brain and in April identified his disease as sporadic fatal insomnia.

He’d later take hours to talk with Kathleen Mendy about her son’s death. Sporadic fatal insomnia and CJD, he explained, are part of the still-mysterious field of neurodegenerative diseases, including Alzheimer’s and Parkinson’s.

Some of these ravages of the brain, such as so-called “Mad Cow,” begin with an infection of prions, or pathogenic proteins, from the outside. CJD in the young also can be caused by prions, often transmitted during surgery.

Like a virus, a prion can essentially “breed.” The virus hijacks human cells, and the prion reshapes other proteins into its own mutated form. And when a prion or virus propagates enough, it can destroy its host.

But there’s a crucial difference: The prion also can come from within. Gambetti believes that Michael’s disease began when the boy’s brain misfolded a protein, creating a prion instead. The defect may then have multiplied out of control and ruined the delicate balance of the body.

It’s not uncommon for the body to make mistakes. Neurons and other cells normally catch and eliminate prions before they replicate. These defensive systems may grow weaker with age; some people may also inherit weaker defenses.

But Michael was a teenager, with no apparent family history of neurodegenerative diseases. Gambetti put the odds of such a case at one in 100 million in the general population; another doctor said it was one in 600 million.

In fact, Michael may be among the youngest ever to be affected by a neurodegenerative disease without an inherited or outside cause.

“We just haven’t seen this disease affect someone this young,” said John Trojanowski, a professor of geriatric medicine at the University of Pennsylvania.

Gambetti, who played a key role in the discovery of fatal insomnia, theorizes that Michael’s illness was random, despite the odds. It may be that, by chance or some unknown factor, Michael’s brain perfectly bred its own pathogen.

“The bodies of all animals are a marvel of things, in positive and negative,” Gambetti said. “They can do things striking for the good, but also for the bad.”

Looking to others

Nearly a year after Michael’s death, Kathleen Mendy finds love and support from family, friends and Compassionate Friends, a local group. But the extreme rarity of Michael’s case is isolating.

When she attended a CJD conference last summer with her twin sister, they met the families of people who had mostly died in middle and old age.

Some nights she goes up to her only child’s room. It’s lined with dozens of sports team caps and trophies. Athletes’ names are still painted on the blades of his ceiling fan, and the UNC comforter is still on his bed.

All that’s new is the shrine on the desk, where Michael’s photo stands near a glazed statue of praying hands.

“Sometimes I think I’m OK, and other times it’s like it just happened last night. It’s like a rollercoaster,” Kathleen Mendy said.

She may have as many logical answers now as she’ll ever get – a medical, if not a spiritual description of why Michael died.

She still doesn’t know what it was that made her son vulnerable. She believes Michael’s concussions triggered his illness, but his doctors haven’t confirmed the idea.

“I’m a little bit resolved that I’ll never hear the answer,” she said. “It would be nice to know, but if I don’t know it, it’s not what matters now.”

She finds hope instead in the idea that she could help others; she’s thinking of writing a book and becoming a public advocate for those who suffer with CJD.

Meanwhile, as Michael’s birthday and the first anniversary of his death approach, Gambetti and one of Michael’s former doctors are preparing to present his case to their respective medical communities. As painful as the case is, “its rarity may contribute to expand the knowledge on this terrible disease,” according to Gambetti.

He hopes his research will one day allow much earlier diagnosis and treatment of fatal insomnia. Such a breakthrough could key medical progress across the spectrum of prion-related diseases, which are fatal in practically all cases.

Gambetti’s research into Michael’s case will soon yield a more immediate result too: He’ll be able to tell caregivers that sporadic fatal insomnia can strike not just the mature, but perhaps people who are just beginning their lives.

And with Michael’s story spreading, the next stricken family may at least know the harrowing path ahead.