Review: Prevalence and dynamics of Helicobacter pylori infection during childhood

Humans and our ancestors have evolved since the most ancient times with a commensal microbiota. The conservation of indicator species in a niche-specific manner across all of the studied human population groups suggests that the microbiota confer conserved benefits on humans. Nevertheless, certain of these organisms have pathogenic properties and, through medical practices and lifestyle changes, their prevalence in human populations is changing, often to an extreme degree. In this Essay, we propose that the disappearance of these ancestral indigenous organisms, which are intimately involved in human physiology, is not entirely beneficial and has consequences that might include post-modern conditions such as obesity and asthma.

Peptic ulcer disease (PUD) is most commonly associated with Helicobacter pylori infection and the use of acetylsalicylic acid (ASA) and nonsteroidal anti-inflammatory drugs (NSAIDs). The management of H. pylori infection has improved radically in recent years; however, the prescription of ASA and NSAIDs has increased over the same period. To evaluate the current global incidence and prevalence of PUD by systematic review of the literature published over the last decade. Systematic searches of PubMed, EMBASE and the Cochrane library. The annual incidence rates of PUD were 0.10-0.19% for physician-diagnosed PUD and 0.03-0.17% when based on hospitalization data. The 1-year prevalence based on physician diagnosis was 0.12-1.50% and that based on hospitalization data was 0.10-0.19%. The majority of studies reported a decrease in the incidence or prevalence of PUD over time. Peptic ulcer disease remains a common condition, although reported incidence and prevalence are decreasing. This decrease may be due to a decrease in H. pylori-associated PUD.

Helicobacter pylori (H. pylori) infection is well known to be associated with the development of precancerous lesions such as chronic atrophic gastritis (AG), or gastric intestinal metaplasia (GIM), and cancer. Various molecular alterations are identified not only in gastric cancer (GC) but also in precancerous lesions. H. pylori treatment seems to improve AG and GIM, but still remains controversial. In contrast, many studies, including meta-analysis, show that H. pylori eradication reduces GC. Molecular markers detected by genetic and epigenetic alterations related to carcinogenesis reverse following H. pylori eradication. This indicates that these changes may be an important factor in the identification of high risk patients for cancer development. Patients who underwent endoscopic treatment of GC are at high risk for development of metachronous GC. A randomized controlled trial from Japan concluded that prophylactic eradication of H. pylori after endoscopic resection should be used to prevent the development of metachronous GC, but recent retrospective studies did not show the tendency. Patients with precancerous lesions (molecular alterations) that do not reverse after H. pylori treatment, represent the "point of no return" and may be at high risk for the development of GC. Therefore, earlier H. pylori eradication should be considered for preventing GC development prior to the appearance of precancerous lesions.