Lucia Libreri, 16, stopped growing when she was 8. Four years later after a battery of tests and visits with medical experts, her parents, Rosalia and Luciano, finally found a doctor who pinned down her problem: celiac disease, a condition scientists say is much more widespread in the USA than previously believed.

This summer, the National Institutes of Health launched the Celiac Disease Awareness Campaign to educate physicians and the public about the prevalence of the disease, the myriad of symptoms it can cause and the tests that can detect it.

People with celiac disease can't digest gluten, a protein found in wheat, rye, and barley - grains commonly used in bread, pasta, cookies and beer. Oats don't contain gluten, but U.S. oats are considered contaminated due to crop rotation and milling.

Less than a decade ago, it was thought celiac disease affected one in every 10,000 Americans, says Michelle Pietzak, clinical assistant professor of pediatrics at the University of Southern California Keck School of Medicine in Los Angeles and founder of website glutenfreemd.com.

But a 2004 report by the health institute, based on research by celiac experts across the country, estimates as many as one in every 133 Americans - approximately 2 million people - may have the disease.

When a person who is genetically prone to celiac disease eats gluten, it triggers an autoimmune response, and the body attacks itself, destroying normal tissues, in particular the villi in the small intestine.

Normally, these tiny, hair-like fingers act to absorb nutrients from food. But when the villi malfunction, the digestive system goes haywire, causing problems such as chronic diarrhea, gas, bloating, reflux and constipation.

A small bit will cause illness

Alexis Jonnson, 23, of Walnut Creek, Calif., spent most of her life battling severe nausea and often was told by doctors it was anxiety. "It felt like the inside of my stomach was being scraped. It wasn't anxiety," says Jonnson, diagnosed at age 17.

In severe cases, such as Lucia Libreri's, a person can't absorb the nourishment needed to grow. But once Lucia, who lives in River Grove, Ill., stopped eating the gluten-packed pastas and breads served up in her family's Chicago-area Italian restaurant, Da Luciano's, she began growing.

"For the first year, it was very difficult to understand the contamination issues. That even a tiny bit of gluten on a spoon or pan could be bad," Lucia's mothers says. "But it's much easier now, second nature."

What many doctors don't know is celiac disease also can manifest itself in ways that have nothing to do with the digestive system. Doctors usually misdiagnose it, mistreat it or miss it altogether, says Peter Green, director of Celiac Disease Center at Columbia University in New York City.

"Studies show there's a great delay in diagnosis in this country. Doctors here are taught that it's rare," says Green, who was educated in Australia where it's considered a common illness.

In one study, Columbia researchers reported it took an average of 11 years for patients to receive a diagnosis.

When Lucia was diagnosed, her parents and six siblings also were tested since it runs in families. Her brother, Peitro, now 18, tested positive. "He'd been anemic and on iron pills for three years and had asthma," Rosalia says. "He was so skinny. We couldn't figure out why."

After three months on a gluten-free diet, Peitro gained 30 pounds. "He's healthy and going off to college," she says.

But some people, such as Lucia's two younger brothers, Aldo and Claudio, may exhibit few or no symptoms. "There were no big outward symptoms in the other two," Rosalia says.

"Don't let the appearance of good health fool you. You may have unseen damage going on inside your body that can catch up with you later," says Alessio Fasano, director of the University of Maryland School of Medicine's Center for Celiac Research in Baltimore.

People with celiac disease have higher rates of osteoporosis, certain cancers and infertility, studies show. "If a family member tests positive, get your other family members tested, too, even if they look healthy," Fasano says.

Gluten-free food available

There are two ways to test for celiac disease. Specific blood tests can be performed, but false negatives are possible. If a blood test is positive, a biopsy of the small intestine is required. The biopsy is considered the gold-standard for diagnosing the disease.

To heal, people must eat a gluten-free diet for the rest of their lives. "Even a tiny taste can trigger an immune response," Pietzak says.

Ten years ago, packaged gluten-free foods were uncommon on grocery shelves, but now stores such as Whole Foods and Trader Joe's offer dozens of choices.

New food labeling laws also help.

In January, the Food and Drug Administration began requiring manufacturers to list ingredients that contain protein derived from eight major allergenic foods, including wheat, says Andrea Levario, executive director of American Celiac Disease Alliance.

The list of restaurants offering gluten-free options is growing, too, and includes chains such as P.F. Chang's China Bistro and Outback Steakhouse, says Elaine Monarch of the Celiac Disease Foundation in Studio City, Calif.

When her children were diagnosed four years ago, Rosalia says finding tasty foods was frustrating. But today, after developing new recipes and importing special ingredients, every item on their restaurant menu has a gluten-free alternative.

"We get customers with celiac disease who really miss eating their favorite foods. When they see we have gluten-free breads and pizzas they light up. I've seen people eat our cannoli and cry they're so happy."