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An African origin for the intimate association between humans and Helicobacter pylori.

ABSTRACT: Infection of the stomach by Helicobacter pylori is ubiquitous among humans. However, although H. pylori strains from different geographic areas are associated with clear phylogeographic differentiation, the age of an association between these bacteria with humans remains highly controversial. Here we show, using sequences from a large data set of bacterial strains that, as in humans, genetic diversity in H. pylori decreases with geographic distance from east Africa, the cradle of modern humans. We also observe similar clines of genetic isolation by distance (IBD) for both H. pylori and its human host at a worldwide scale. Like humans, simulations indicate that H. pylori seems to have spread from east Africa around 58,000 yr ago. Even at more restricted geographic scales, where IBD tends to become blurred, principal component clines in H. pylori from Europe strongly resemble the classical clines for Europeans described by Cavalli-Sforza and colleagues. Taken together, our results establish that anatomically modern humans were already infected by H. pylori before their migrations from Africa and demonstrate that H. pylori has remained intimately associated with their human host populations ever since.

SUBMITTER: Linz B

PROVIDER: S-EPMC1847463 | biostudies-literature | 2007 Feb

REPOSITORIES: biostudies-literature

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An African origin for the intimate association between humans and Helicobacter pylori.

Linz Bodo B Balloux François F Moodley Yoshan Y Manica Andrea A Liu Hua H Roumagnac Philippe P Falush Daniel D Stamer Christiana C Prugnolle Franck F van der Merwe Schalk W SW Yamaoka Yoshio Y Graham David Y DY Perez-Trallero Emilio E Wadstrom Torkel T Suerbaum Sebastian S Achtman Mark M

Nature 20070207 7130

Infection of the stomach by Helicobacter pylori is ubiquitous among humans. However, although H. pylori strains from different geographic areas are associated with clear phylogeographic differentiation, the age of an association between these bacteria with humans remains highly controversial. Here we show, using sequences from a large data set of bacterial strains that, as in humans, genetic diversity in H. pylori decreases with geographic distance from east Africa, the cradle of modern humans. ...[more]

PMID: 17287725

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Project description:ObjectivesThe role of Helicobacter pylori (H pylori) in gastroesophageal reflux disease (GERD) remains controversial, particularly in children, because there are limited published data. Adult studies suggested that H pylori infection may protect against GERD by causing atrophic gastritis, which leads to reduced gastric acid secretion. The objective of our study was to determine the role of H pylori infection in the development of GERD in a pediatric population.Patients and methodsA retrospective analysis of 420 patients (M:F = 214:206) who underwent esophagogastroduodenoscopy (EGD) with biopsies between January 2000 and April 2006 was conducted. Patient demographics, clinical indications for EGD and the prevalence of reflux esophagitis (RE), the biomarker for GERD, in 2 groups, H pylori positive and H pylori negative, were reviewed. The prevalence of RE in the H pylori-positive and H pylori-negative groups was further analyzed on the basis of sex and age (<1 year, 1-10 years, >10 years). The mean age of the study population was 8.2 years (range 0-20 years). The clinical indications for EGD were as follows: recurrent abdominal pain (n = 186, 44%), malabsorption (n = 80, 19%), persistent vomiting (n = 80, 19%), suspected eosinophilic gastrointestinal disorders (n = 63, 15%), and others such as upper gastrointestinal bleeding or inflammatory bowel disease surveillance (n = 11, 3%). Statistical analysis was performed by using chi test, Fisher exact test, and multivariate logistical regression analysis.ResultsAmong the 420 patients, 16 patients (3.8%) were positive for H pylori and 167 patients (39.8%) were found to have RE. Thirteen patients with H pylori were found to have histologic evidence of RE. The prevalence of RE in the H pylori-positive population was 81.3% compared with 38.1% in the H pylori-negative population (P < or = 0.05). There were no patients with H pylori in the youngest age group. In the second age group (1-10 years), 100% of the H pylori-positive patients had RE, whereas 44.6% of the H pylori-negative patients had RE (P < or = 0.05). Both male and female patients with H pylori had a higher prevalence of RE, 77.8% and 85.7%, respectively. On a multivariate logistical regression, for the overall study cohort, H pylori-positive patients had an odds ratio of 5.79 of developing RE compared with H pylori-negative patients (P < or = 0.05).ConclusionsOur study results indicate that there is a significantly higher prevalence of RE in an H pylori-infected cohort independent of age or sex. The findings suggest that H pylori infection in children is positively associated with RE.

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An African origin for the intimate association between humans and Helicobacter pylori.

Publications

An African origin for the intimate association between humans and Helicobacter pylori.

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