Another autoimmune disease caused by gluten intolerance is dermatitis herpetiformis, which mainly involves the skin. A severe, itchy, blistering skin rash shows up, usually on the elbows, knees, buttocks, and back; in severe cases, the rash can be on any skin surface. Dermatitis herpetiformis is diagnosed by a skin biopsy, but if an intestinal biopsy is also performed, damage to the villi is usually found, although to a lesser degree than that which occurs in celiac disease. Usually, there are no digestive symptoms of dermatitis herpetiformis, but it is treated with a gluten-free diet as well as with medication for the rash.
Celiac disease can be more difficult to diagnose than dermatitis herpetiformis because its symptoms often mimic other digestive diseases such as irritable bowel disease, Crohn disease, ulcerative colitis, and intestinal infections. Complicating the matter is the fact that people with untreated celiac disease often develop lactose intolerance (the symptoms of which also include gas, bloating, and diarrhea) because of the damage to the intestinal villi. Lactose, the sugar in milk and other dairy products, is digested by the enzyme lactase, which is located on the villi. Usually, lactose intolerance disappears within about 2 to 12 months of starting a gluten-free diet. In some cases, however, a person remains lactose intolerant and must continue to avoid dairy products as well as gluten.
Once diagnosed, the only treatment of celiac disease is lifelong, complete elimination of gluten-containing foods from the diet. With gluten elimination, symptoms may disappear within a few days, but complete healing of the small intestine may take three to six months or, in some cases, up to two years. Eating even a small amount of gluten can make a person sick again. In a small percentage of people, a gluten-free diet does not improve symptoms; these people may need to be treated with steroids or immunosuppressive drugs.
Who gets this disease?
Celiac disease commonly shows up in children, but it has been diagnosed in people of all ages, mainly because not everyone with celiac disease experiences symptoms right away. In studies from several countries, including Scotland, England, the United States, and Canada, almost 50% of those with a new diagnosis of celiac disease did not experience symptoms. Several factors may influence the onset of symptoms in those genetically predisposed to the disease. It is believed that the longer an infant is breast-fed, the later the symptoms of celiac disease appear. (However, it is not known if breast-feeding can prevent celiac disease.) The age at which a person began eating gluten and how much gluten he consumes may also affect the onset of celiac disease. A bacterial or viral infection or the stress caused by pregnancy or surgery may trigger symptoms in susceptible individuals.
Since celiac disease is an inherited disease, all first-degree family members — parents, siblings, and children — of people with celiac disease should be screened. About 10% to 15% of first-degree family members will also have celiac disease. In addition, celiac disease often occurs in those with another autoimmune disorder, such as Type 1 diabetes, thyroid disease, Sjögren syndrome, rheumatoid arthritis, and Addison disease. Celiac disease is found in 5% to 7% of people who have Type 1 diabetes; some researchers recommend that all children with Type 1 diabetes be screened for celiac disease.
Women are about twice as likely to have celiac disease as men, and the disease is most common in people of European descent (the incidence is particularly high in Scandinavian countries, Italy, and Ireland). It is less common in those of African or Asian heritage. In countries where there is greater awareness of the disease, there is increased diagnosis. In Central Europe, 1 in 200 people has celiac disease. In Italy, every child is screened for celiac disease by age six; approximately 1 in 184 Italians has the disease. In the United States, celiac disease is largely unrecognized and underdiagnosed. While only about 500,000 Americans have been diagnosed with the disease, a recent study suggests that as many as 1 in 133 Americans may have celiac disease. Underdiagnosis of celiac disease is a serious concern, because the risk of long-term complications increases the longer it goes untreated.