Seroprevalence of Helicobacter pylori, incidence of gastric cancer, and peptic ulcer-associated hospitalizations in a Canadian Indian population

Abstract

The living conditions of many aboriginal communities in Canada may place their residents at risk for H. pylori infection. Our aims were to determine: (1) the seroprevalence of H. pylori in a traditional Indian community, (2) the clinical relevance of H. pylori infection in this population, and (3) if H. pylori could be identified by polymerase chain reaction from the local water. A demographic questionnaire was administered, and blood was collected from subjects in an Indian community in northwestern Manitoba. The serum was analyzed by ELISA for IgG to H. pylori and to CagA. ABO and Lewis antigens were tested. Age-adjusted incidence of gastric cancer and of hospitalizations associated with diagnoses of peptic ulcer were determined for the Indian and non-Indian Manitoba population in the years 1989-1993. Nested PCR was performed on lake water using H. pylori-specific primers and the amplicons probed with an internal Dig-labeled probe. Three hundred six (59%) of approximately 518 individuals who were resident in the community at the time of the study were enrolled. The ELISA for H. pylori was positive in 291 (95%). There was no association between H. pylori seropositivity and age, sex, gastrointestinal complaints, medications, housing characteristics, and ABO or Lewis antigen status. CagA was positive in 84.5% of infected subjects. The average annual age-adjusted incidence of hospitalizations associated with diagnoses of peptic ulcer disease in Manitoba was higher for treaty-status Indians (394.3/100,000) than for non-Indians (203.8/100,000), but gastric cancer rates were similar (11.2/100,000 vs 11.6/100,000). No H. pylori DNA was detected in the lake water. In conclusion, the seroprevalence of CagA-positive H. pylori is high in this representative Manitoban Indian community. This may be associated with an increased risk for peptic ulcer disease but is not associated with an increased risk for gastric cancer.