Natural history and epidemiology ofHelicobacter pyloriinfection

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.

Upper gastrointestinal endoscopic findings and prevalence of Helicobacter pylori infection among adult patients with dyspepsia in northern Tanzania

“…Endoscopy is the ideal procedure for identifying organic diseases of the foregut, but this service is yet to be widely available in developing countries including Tanzania. H. pylori infection is known to be among the most common human infections worldwide; approximately 50% of the world's population is infected with H. pylori (Brown, 2000;Go, 2002). H. pylori infection is associated with various upper gastrointestinal pathologies such gastritis, peptic ulcers and gastric cancer (Graham, 1994;Blaser, 1995;Go, 2002;Marshall & Winsdor, 2005).…”

“…H. pylori infection is known to be among the most common human infections worldwide; approximately 50% of the world's population is infected with H. pylori (Brown, 2000;Go, 2002). H. pylori infection is associated with various upper gastrointestinal pathologies such gastritis, peptic ulcers and gastric cancer (Graham, 1994;Blaser, 1995;Go, 2002;Marshall & Winsdor, 2005). Because of the strong association between this gram negative bacterium infection and gastrointestinal diseases and its high prevalence rate in developing countries (Suerbaum & Michetti 2002;Frenck & Clemens, 2003;Kazuo et al, 2004;Xia et al, 2005;Tkachenko et al, 2007;Kate et al, 2009)., H. pylori infection is among the leading gastroenterological public health problems in developing countries (Kate et al, 2009).…”

Genetic and Environmental Factors in the Immunopathogenesis of Atopy: Interaction of <i>Helicobacter pylori</i> Infection and <i>IL4</i> Genetics

“…Helicobacter pylori is the most common infectious gastrointestinal pathogen that infects gastric mucosa in early life and often leads to a life-long chronic gastritis (reviewed in [13]). It induces a vigorous Th1 mediated inflammatory response[ 14].…”

Prevalence of Helicobacter pylori among patients with dyspepsia and correlation between endoscopic and histological diagnosis

“…One half of the world's population has H. pylori infection, with an estimated prevalence of more than 90% in developing countries. [2][3][4][5][6] In our country, the reported prevalence of H. pylori ranged from 30% to 67%. [7][8][9][10][11] This bacterium colonizes human gastric mucosa and can elicit lifelong inflammatory and immune responses, with release of various bacterial and host dependent cytotoxic substances.…”