Seroprevalence of Helicobacter pylori in school-aged Chinese in Taipei city and relationship between ABO blood groups

AIM: To explore the seropositive rate of antibodies against H. pylori (anti-HP) in Taipei City and to compare the relationship of ABO blood groups and H. pylori infection. METHODS: In 1993, high school students in Shih-Lin District were randomly selected for blood samplings by their registration number at school. In addition, similar procedures were performed on the well-children clinics of Taipei Veterans General Hospital. Besides, randomly selected sera from the adults who took the physical examination were recruited for evaluation. Informed consents were obtained from all the subjects before blood samplings and parents were simultaneously informed for those who were younger than 18-year-old. Blood tests for anti-HP and ABO blood groupings were performed by enzyme-linked immunosorbent assay. Chi square tests were used for the comparisons between seroprevalence of H. pylori and ABO blood groups. RESULTS: Totally, 685 subjects were recruited (260 children aged 1-14 years, 425 high school students aged 15-18 years) were evaluated, and another 88 adult healthy volunteers were studied as well for comparison. The age-specific seropositive rate of anti-HP was 1.3% at age 1-5 years, 7.7% at age 6-10 years, and 11.5% at age 11-14 years. The seroprevalence of H. pylori infection was abruptly increased in young adolescence: 18.6% at age 15 years, 28.1% at age 16 years, 32.4% at age 17 years and 41.0% at age 18 years, respectively. In the 425 high school students, ABO blood groupings were performed, which disclosed 48.5% (206/425) of blood group O, 24% (102/425) of blood group A, 21.8% (93/425) of blood group B and 5.6% (24/425) of blood group AB. In comparison of the subjects with blood group O and the other blood groups, no statistical significance could be identified in the seroprevalence of H. pylori (P=0.99). CONCLUSION: The seroprevalence of H. pylori infection in Taipei City in adults is similar to the developed countries, and the abrupt increase of H. pylori during high school may be resulted from marked increase of interpersonal social activities. Although blood group 0 was reported to be related top H. pylori infection in previous literature, we found no association between H. pylori infection and ABO blood groups.