Medline and PubMed databases were searched on epidemiology of Helicobacter pylori for the period of April 2013-March 2014. Several studies have shown that the prevalence of H. pylori is still high in most countries. In north European and North American populations, about one-third of adults are still infected, whereas in south and east Europe, South America, and Asia, the prevalence of H. pylori is often higher than 50%. H. pylori remains highly prevalent in immigrants coming from countries with high prevalence of H. pylori. However, the lower prevalence of infection in the younger generations suggests a further decline of H. pylori prevalence in the coming decades. Low socioeconomic conditions in childhood are confirmed to be the most important risk factors for H. pylori infection. Although the way the infection is transmitted is still unclear, interpersonal transmission appears to be the main route. Finally, H. pylori recurrence after successful eradication can still occur, but seems to be an infrequent event.The epidemiology of Helicobacter pylori has been changing over the last decades, with a decline of the prevalence of the infection in most countries. The changing epidemiology of the bacterium has been associated with a parallel decline in peptic ulcer disease and gastric cancer [1] and may have an impact on the changing epidemiology of other diseases, such as gastroesophageal reflux disease, allergies, and asthma [2].Over the last year, several studies reported data on the prevalence of H. pylori infection in both adults (Table 1) and children (Table 2) in Europe, Canada, Latin America, Asia, and Africa.
Prevalence of Helicobacter pylori InfectionIn Europe, the prevalence of H. pylori seems to be lower in Northern countries than in Southern and Eastern countries. In the Netherlands, a randomly selected sample of 1550 blood donors from four different regions was tested for the presence of antibodies against H. pylori and the CagA antigen [3]. In this study, only native Dutch subjects were evaluated excluding non-European immigrants. This study reported a 32% prevalence of H. pylori infection, with 28% of H. pyloripositive subjects carrying a CagA-positive strain. The seroprevalence of H. pylori declined from 48% in subjects born between 1935 and 1946 to 16% in those born between 1977 and 1987, as a likely consequence of a birth cohort effect. Also the proportion of CagApositive subjects decreased from 38% to 14% in the same age cohorts. These data would suggest that a further reduction of H. pylori prevalence in the Netherlands over the coming decades could be expected.Additionally, from the Netherlands, a populationbased prospective study of a cohort of more than 6500 pregnant women was published [4]. This study found that the prevalence of H. pylori in Dutch women was 24%. The most important finding was that the prevalence of H. pylori was much higher in non-Dutch women with 64% of them being H. pylori seropositive. Moreover, in the latter group, infected subjects born abroad (first-generation i...