Generate text that best answers this question: viral infections
The prevalence of celiac disease in the United States.
OBJECTIVES: The prevalence of celiac disease (CD) in the United States is unknown. We sought to estimate CD prevalence nationwide by using a nationally representative sample. METHODS: This study included 7,798 persons aged 6 years or older who participated in the National Health and Nutrition Examination Survey 2009-2010. Serum samples from all participants were tested for immunoglobulin A (IgA) tissue transglutaminase antibodies and, if findings were abnormal, also for IgA endomysial antibodies. Information about prior diagnosis of CD and use of a gluten-free diet (GFD) was obtained by direct interview. CD was defined as having either double-positive serology (serologically diagnosed CD) or a reported diagnosis of CD by a doctor or other health-care professional and being on a GFD (reported clinical diagnosis of CD). RESULTS: CD was found in 35 participants, 29 of whom were unaware of their diagnosis. Median age was 45 years (interquartile range, 23-66 years); 20 were women and 29 were non-Hispanic white. The prevalence of CD in the United States was 0.71% (95% confidence interval (CI), 0.58-0.86%), with 1.01% (95% CI, 0.78-1.31%) among non-Hispanic whites. In all, 55 participants reported following a GFD, which corresponded to a prevalence of 0.63% (95% CI, 0.36-1.07%). CONCLUSIONS: The prevalence of CD in the United States was 0.71% (1 in 141), similar to that found in several European countries. However, most cases were undiagnosed. CD was rare among minority groups but affected 1% of non-Hispanic whites. Most persons who were following a GFD did not have a diagnosis of CD.