Long‐term Helicobacter pylori infection — from gastritis to gastric cancer

The prevalence of H. pylori colonization of the gastric mucosa in asymptomatic people increases with age, reaching 40% by the age of 50 in developed countries and nearly 80% by the age of 30 in many developing countries.5 It has been suggested that this phenomenon appears related to the differences of sanitary practices between developed and developing countries, 6 as most risk is acquired during childhood, sanitary practices during that period would be most reflective of an individual's risk of infection.In our studies of an asymptomatic Japanese population, 7 we reported that the incidence of H. pylori infection for people born after 1960 increased at 1% per year as in other developed countries, whereas for those born before 1950 the prevalence was high (70-80%) and relatively constant.These data suggest the presence of at least two cohorts that differ in risk for H. pylori infection and suggest there has been a major change in the age-specific incidence of H. pylori infection in Japan that became evident approximately 50 years ago.It is of interest that the frequency of H. pylori infection for those under the age of 30 follows a pattern