title: Review article: natural history and epidemiology of Helicobacter pylori infection.
abstract: Helicobacter pylori is a common bacterium infecting about half the world's population. It is causally linked with a diverse spectrum of gastrointestinal clinical disorders including peptic ulcer disease, gastric cancer, and gastric MALT lymphoma. The principal reservoir is the human stomach, and transmission probably occurs by person-to-person passage. Prevalence rates are generally much higher in developing countries compared to developed countries, although there are subgroups within many regions with higher H. pylori prevalence than in the general population. The prevalence of H. pylori varies by geographical location, ethnic background, socioeconomic conditions, and age. Recent studies suggest decreasing prevalence in developed countries or those with rapidly improving socioeconomic conditions. Comparative studies of the two fully sequenced H. pylori genomes are providing understanding of its large genetic diversity and bacterial virulence factors. The discovery of the type IV secretion system in H. pylori and its role in translocation of the CagA protein from the bacterial cell into the host epithelial cell provides insight into how host-bacterial interaction may lead to host disease. Cytokine promoter polymorphisms are determinants important in host gastric acid secretion status. Understanding the changing trends in H. pylori epidemiology, details of its transmission pathways, and the bacterial and host determinants leading to gastroduodenal disease remain the challenges in this area. Global epidemiological studies, advances in technology, and medical interventions have converged to help clarify the mechanisms of interaction between this ubiquitous micro-organism and its host that result in its diverse clinical manifestations.
authors.affiliation: GI Section, Veterans Administration Salt Lake City Health Care System, Division of Gastroenterology, University of Utah School of Medicine, Salt Lake City, Utah 84148, USA. mae.go@med.va.gov
authors.forename: M F
authors.initials: MF
authors.lastname: Go
mesh_terms: D000328:Adult; D018798:Anemia, Iron-Deficiency / Q000150:complications; D000942:Antigens, Bacterial; D001426:Bacterial Proteins / Q000235:genetics; D002648:Child; D019049:Developed Countries; D003906:Developing Countries; D005767:Gastrointestinal Diseases / Q000382:microbiology*; D016481:Helicobacter Infections / Q000150:complications / Q000453:epidemiology / Q000635:transmission*; D016480:Helicobacter pylori / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity; D006801:Humans; D012307:Risk Factors; D012959:Socioeconomic Factors; D013274:Stomach Neoplasms / Q000209:etiology / Q000382:microbiology
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C080866:cagA protein, Helicobacter pylori