Epidemiology of Helicobacter pylori and Mechanisms of Carcinogenesis

Abstract

Soon after the discovery of H. pylori , numerous studies based on serological surveys highlighted an increasing prevalence of H. pylori infection with age within a population, which was inversely related to the socio-economic status [ 14 ]. This was related to the so-called cohort phenomenon: each age group has a different prevalence of an infection acquired primarily during childhood and lasting lifelong. The risk of acquiring the infection has decreased over the years due to improvement in socio-economic conditions.Regarding Europe, the prevalence of H. pylori infection according to the year of birth has decreased quickly and dramatically in countries from Northern Europe (e.g. Finland), whereas it remains high in some countries from Southern Europe (especially Portugal) [ 11 ]. Indeed, H. pylori infection remains a frequent and early event in Portugal [ 13 ].A gastric biopsy-based study conducted in the Brussels area (Belgium) over a 20-year period has also nicely shown that the prevalence was much higher in children (0-9 years old) with a North African origin compared to children with Western European origin. Therefore, these data show the effects of time, age and ethnicity on