Helicobacter pylori: a poor man's gut pathogen?

Abstract

Helicobacter pylori is one of the human pathogens with highest prevalence around the world; yet, its principal mode of transmission remains largely unknown. The role of H. pylori in gastric disease and cancer has not been established until the end of the 20th century. Since then, its epidemiology has been extensively studied, and an accruing body of literature suggests that not all humans are equally at risk of infection by this gut pathogen. Here, we briefly review the different epidemiological aspects of H. pylori infection with emphasis on those factors related to human poverty. The epidemiology of H. pylori infection is characterized by marked differences between developing and developed countries, notably among children. In addition, congruent lines of evidence point out to socioeconomic factors and living standards as main determinants of the age-dependent acquisition rate of H. pylori, and consequently its prevalence. These data are alarming in the light of the changing global climate and birth rate, which are expected to change the demography of our planet, putting more children at risk of H. pylori and its complications for years to come.

Figure 1

A. H. pylori-related articles published between 1989 and 2009. Data are collected from search results on ISI Web of Science (WoS, URL: http://www.isiwebofknowledge.com) with "Helicobacter pylori OR H. pylori" as search string. B. Example infectious agents in literature. The PubMed literature database (URL: http://www.ncbi.nlm.nih.gov/pubmed) was searched for articles whose titles include the words: Mycobacterium tuberculosis (M. tuberculosis), Staphylococcus aureus (S. aureus), Helicobacter pylori (H. pylori), Escherichia coli (E. coli), and the human immunodeficiency virus (HIV). Although H. pylori is a recently discovered pathogen, it has more records in literature than well-established pathogens such as S. aureus and M. tuberculosis but is exceeded by HIV and E. coli, the latter being possibly the most cited bacterium and the most commonly used organism in the laboratory.

Figure 2

Cartograms showing the unequal distribution of (A) wealth, (B) human poverty indices, and (C) total births around the globe. The cartograms, or map projections, were obtained from URL: http://www.worldmapper.org with permission (^© Copyright SASI Group, University of Sheffield; and Mark Newman, University of Michigan). They had been generated by a diffusion-based method [91] and were included in the Worldmapper project [92-94].