Recent changes in the prevalence of Helicobacter pylori infection among children and adults in high- or low-incidence regions of gastric cancer in China.

BACKGROUND: The prevalence of Helicobacter pylori (H. pylori) infection varies by geographic locations. Studies indicate that the infection rate of H. pylori was previously high in China but that rates had been declining worldwide over recent decades.

THE AIMS OF OUR STUDY WERE: (1) to determine the current prevalence of H. pylori infection among children and adults residing in areas with high (Muping County, Shandong) and low (Yanqing County, Beijing) incidences of gastric cancer in China, and (2) to compare the prevalence for 2006 with the prevalence for the early 1990s.

METHODS: Using Warthin-Starry silver staining of gastric mucosal biopsy specimens and H. pylori stool antigen tests (HpSA), we tested a total of 2065 asymptomatic children aged 8 - 15 years and adults aged 40 - 79 years in the above two regions from May to July 2006. We evaluated 520 children and 526 adults from Muping, and 516 children and 503 adults from Yanqing. Subjects were selected randomly and H. pylori status was determined by HpSA in children and either HpSA or histology of gastric biopsies in adults. Data obtained in the early 1990s in the same two areas of China were also collected and studied.

RESULTS: For children, the prevalence of H. pylori infection was significantly higher in Muping (37.69%) than it was in Yanqing (25.58%, P < 0.001). In both regions, the prevalence of H. pylori increased with age but was not related to gender. A significant difference was observed between 8 - 9-years old and 10 - 11-years old (P < 0.05), but not between other adjoining age groups (P > 0.05). From 1991 to 2006 H. pylori prevalence among 8 - 10-year-old children decreased in Muping (60.00% vs 32.07%, P < 0.001), but not Yanqing (24.06% vs 19.10%, P > 0.05). In the adult group, H. pylori prevalence was 50.95% in Muping, which was significantly higher than the 41.35% positive rate in Yanqing (P < 0.01). But there were no statistically significant differences between different age groups of 40 - 49, 50 - 59, and 60 - 79 years, or between males and females. A significant decrease in H. pylori prevalence in both regions was observed when the results of 2006 were compared with the data obtained in 1990 in Muping (50.95% vs 73.78%, P < 0.001) and in 1992 in Yanqing (41.35% vs 55.35%, P < 0.01).

CONCLUSIONS: After fifteen years, the prevalence of H. pylori infection among both children and adults remained significantly higher in areas with a high incidence of gastric cancer in China compared with that in areas with a low incidence of gastric cancer. H. pylori infection rates have decreased in the general Chinese population during recent years.