Background: Helicobacter pylori (Hp) is a gastric pathogen associated with development of duodenal or stomach ulcers, stomach cancer, and mucosa associated lymphoid-tissue (MALT) lymphomas. While Hp prevalence is declining in many regions, it remains the leading infectious cause of cancer worldwide. In the United States prevalence varies by geographic location, ethnic background, socioeconomic status, and age. This pilot project seeks to understand the role of Hp infection in the development of stomach cancer among Native Americans of Northern Arizona, where stomach cancer incidence rates are approximately three times higher than the general Arizona population and it is the leading cause of cancer mortality. Methods: A cross-sectional survey based on a random sample of households selected using census block vectors for tribal lands overlaid onto satellite imagery. Potential household structures were marked and randomly sorted with recruitment goals set to be proportional to underlying population size. Houses were ‘ground-truthed’ for eligibility and residents approached for participation. A total of 72 households were recruited between June-August 2018 with 105 self-identified Navajo >18 years old living in three communities in northern Arizona participating. Participants were assessed on household and individual level factors associated with infection. A urea breath test (UBT) was performed to test for active infection. We used logistic regression, adjusted for household clustering, to calculate odds ratios (aOR) and 95% confidence intervals (CI) for associations between UBT results and individual and household factors. Results: Active Hp infection was found in 66 of the 101 participants with valid UBT, crude prevalence of 65.4%. Male participants were more likely to be positive (aOR=2.89, 95% CI, 1.03-8.09). Participants with an unregulated household water source had the highest odds for positive UBT (aOR=8.85, 95% CI, 1.50-53.38). There was no association with age or education and a modest association with history of gallbladder disease. Only 23.8% reported they had ever heard of Hp infections and 12.9% previously tested for the infection. Conclusion: Prevalence of Hp is high among individuals in these Navajo communities. Use of household water that was not regulated, was strongly associated with active Hp infection. Further work is needed to determine if there is geographic variation and what Hp substrains are involved for this population. Attention also needs to focus on developing strategies to reduce the infection and target earlier detection.

Citation Format: Robin B Harris, Rachel Begay, Priscilla R Sanderson, Carmenlita Chief, Fernando Monroy, Heidi E Brown, Eyal Oren. Helicobacter pylori infections in Navajo communities of Northern Arizona [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr D109.