Helicobacter pylori (H. pylori) bacteria play a significant role in the etiology of gastric and duodenal ulcers, gastro-esophageal reflux disease and gastric adenocarcinoma. Intellectually disabled/developmentally disabled (ID/DD) adults are reported to have H. pylori infection at approximately twice the rate of the general population and experience recurrence at a seven-fold higher rate, contributing to increased mortality due to gastric cancer. The oral cavity may serve as a reservoir for H. pylori and subsequently contribute to the recurrence of gastric infection. Numerous studies have identified H. pylori in dental plaque, an environment that is relatively resistant to systemic antibiotics. Systemic antibiotics are used to treat H. pylori infections but do not appear to eradicate H. pylori in the mouth. The oral status of ID/DD adults is reported to be poor due to inadequate oral hygiene, leading to increased plaque, caries and periodontal disease. Furthermore, poor oral status (periodontal disease) has been associated with H. pylori seropositivity. While ID/DD adults have elevated rates of H. pylori gastric infections, nothing is known about the prevalence of H. pylori in their oral cavities. The proposed exploratory research will address the following questions in this disadvantaged population: 1) What is the prevalence of H. pylori in the dental plaque in ID/DD adults? 2) Is poor oral status associated with H. pylori gastric infection? and 3) Does H. pylori persist in the dental plaque of ID/DD adults after systemic antibiotic treatment, and if so, is it associated with recurrence of gastric infection? This epidemiological study of 112 institutionalized ID/DD and 112 control subjects will involve oral examinations, indices, dental plaque sampling, and C13 Urea Breath Tests at baseline to determine prevalence. Nested Polymerase Chain Reaction (PCR) analyses will be used to detect H. pylori in the dental plaque. For those ID/DD subjects who have a positive gastric H. pylori test at baseline, repeated oral sampling and gastric tests will be performed over 1 year to determine persistence. If poor oral health status and oral H. pylori prevalence are correlated with gastric H. pylori infections, a future pilot clinical trial will be conducted to investigate the concordance between genetic strains of H. pylori in the mouth and stomach, the effect of various interventions on oral health, oral H. pylori prevalence, and H. pylori gastric infections in ID/DD adults. The proposed research responds to the Surgeon General's National Call to Action to conduct studies to elucidate underlying mechanisms and determine any causal associations between oral infections and systemic conditions. The proposed research also addresses the need to reduce health disparities, improve quality of life, and reduce morbidity and mortality in vulnerable populations. Project Narrative: Helicobacter pylori infections are a significant cause of morbidity in institutionalized intellectually and developmentally disabled (ID/DD) persons in the United States. There is reason to investigate whether there is an association between oral health and H. pylori infection and recurrence of H. pylori infection in ID/DD individuals. The proposed study would provide pilot data for a clinical trial and add to the knowledge concerning oral status and H. pylori infection. Our results may demonstrate that professional oral care is medically necessary for the reduction of morbidity and mortality caused by H. pylori infection in ID/DD persons. This research is consistent with the Healthy People 2010 overarching goal of eliminating health disparities. It is also consistent with the Surgeon General's National Call to Action to determine oral health care needs, refine protocols of care for special needs patients, and to conduct studies to determine associations between oral infections and systemic conditions.