He looks like a normal 12-year-old boy at first glance. But a mystery rages behind Felix Salaiz’ brown eyes. For the first two years of his life, Felix grew up as most children do. He’d laugh. He’d seek his parents out. His eyes glimmered with curiosity. But then, at around 2 years old, he started to lose it. Felix regressed.

His mother, Marcela Salaiz, recalls the changes. She said it was as if Felix had descended into his own private world—one nearly inaccessible from this side of the divide. “His eyes became like, dead,” says Marcela Salaiz, pointing to a photograph of Felix taken when he was 2 and a half years old that hangs in their Salinas home.

Salaiz didn’t know it at the time, but Felix was showing the classic symptoms of autism, a fast-growing behavioral disorder that is now more common than childhood cancer and just as common as juvenile diabetes. Felix is now nearing puberty. But he still can’t laugh or relate to his environment in any sensible way. He still wears diapers. He still bites people—including his mother—if he’s in a bad mood. She has the scars on her arms to prove it. And Felix still can’t speak.

“He’s never said, ‘Mom,’” Salaiz says matter-of-factly.

On a recent Thursday evening she’s standing beside Felix, a thin, dark-haired boy who’s lying on his bed playing with his favorite toys: a tin bucket, pencils and a newspaper.

Felix occasionally glances up at his mother, but reveals no hint of grasping the meaning of her words. Instead, he’s immersed in his play, which consists of holding the bucket close to his face and tapping it lightly with a pencil.

“He likes the sound of metal,” is the best explanation Salaiz can offer up for his behavior. “This is what he does every night.”

When he tires of the bucket, Felix grabs the pencils and lets them slip from his hand—one by one—onto the bed. Or he tears a slice of the newspaper, blows at it softly for a few minutes, and then crumples it and places it in a neat pile next to him. He does these things for hours on end.

Felix suffers from an acute form of autism, a neurological disorder that attacks a person’s ability to talk, socialize and respond to anything around him. After years of attending special education courses offered through the Monterey County Office of Education (MCOE)—the largest provider of such classes for autistic children in the county—Felix is still severely behind other children his age.

Autism diagnoses have been on a steep rise nationwide in recent years. In 1998, the US incidence of autism amounted to one out of every 400 births. Now that rate is one out of every 166 births, according to the US Department of Health and Human Services’ Centers for Disease Control. “We have an epidemic on our hands,” US Rep. Dan Burton (D-Ind.) declared recently, echoing a growing chorus of doctors, researchers and parents concerned about the increasing autism rates.

As the number of autism-related disabilities spikes nationwide, the burden of educating autistic kids falls squarely on the shoulders of school districts and county offices of education. These agencies must find the resources to pay for all children’s special-education needs, even though districts receive a fraction of the money they need from state and federal sources. The result is that parents, who are always looking for more services, are often pitted against districts, which are trying to keep costs from spiraling out of control.

Not all cases of autism are as grave as Felix’s. There are many moderate- or high-functioning autistics who can talk a little, or respond to limited direction from parents or teachers. Regardless of where they fall on the scale, all autistic children are, under federal law, eligible for intensive—and costly—special-needs programs to help improve their development. In most cases, the earlier they get involved with the programs, and the more intensive those programs are, the better their chances are for improvement.

Meanwhile, on the scientific front, researchers are frantically searching for a root cause to the autism epidemic. Little is known for sure at this stage. But what investigators are finding points to one or several environmental triggers that bring on autism symptoms in genetically susceptible children—a harrowing thought, since nobody is really sure yet what those triggers are.

Autism is still a new epidemic, and no one has proved without a shadow of a doubt what causes it. But in less than a decade, it has become one of the most inscrutable mysteries of the medical world—one that is touching the lives of an ever-increasing number of people in this country and around the world.