Seroprevalence of cytotoxin-associated gene A positive Helicobacter pylori strains in Changle, an area with very high prevalence of gastric cancel in South China

Abstract

Background: Helicobacter pylori, especially the CagA-positive strains, are closely associated with peptic ulcers and gastric cancers. We performed a large scale gastric cancer screening project and examined the prevalence of H. pylori and CagA-positive strains in Changle, China, an area with one of the World's highest gastric cancer mortality. We also compared the prevalence with that in Hong Kong which has one-tenth of the gastric cancer mortality of that in Changle. Methods: A total of 2424 subjects in Changle and 523 subjects in Hong Kong had endoscopic examination and venesection. Sera were tested for anti-H. pylori antibody and anti-CagA antibody and correlated with endoscopic findings. Results: In Changle, 80.9% of the subjects were H. pylori carriers. Out of 551 carriers, 408 (74%) were positive for anti-CagA antibody. A total of 76% and 87% of the asymptomatic and gastric cancer patients were positive for anti-CagA antibody, respectively (P > 0.05). Compared to Hong Kong, there was a significantly (P < 0.0001) higher prevalence of CagA-positive strains in asymptomatic subjects in Changle (76%) than in Hong Kong (28%), but not in peptic ulcers or gastric cancers. Conclusions: Subjects in Changle had a high prevalence of H. pylori infection and a high prevalence of the CagA-positive strains. The contrast in the prevalence of CagA-positive strains, in asymptomatic subjects in two areas with differing gastric cancer mortality, supports the pathogenic role of CagA-positive strains in gastric carcinogenesis.