How come I've got it? (A review of Helicobacter pylori transmission).

Numerous epidemiological studies have shown the two main risk factors for Helicobacter pylori acquisition: childhood and low socio-economic level both in developing and developed countries. Nevertheless, in the absence of ubiquitous extra-human reservoir(s), the route(s) for person-to-person transmission remains undetermined. Very recent data favour the oro-oral route: besides gastric mucosa, mouth might be a sanctuary site and the oro-oral transmission hypothesis seems applicable worldwide. Nevertheless, the gastro-oral route (vomiting, gastro-oesophageal reflux) is still possible and deserves further research. In developing countries, feco-oral transmission (perhaps through the water supply) might be a significant mechanism of human contamination both for primary infection in children and perhaps, reinfection in adults.