Abstract
Helicobacter pylori is found predominantly in human gastric mucosa. Transfer of the bacterium remains an open topic, but it is likely that infection is usually acquired at a young age, particularly where lower socio-economic conditions prevail. Transmission via an external source such as water supply is a possibility but, in general, infection is probably passed from person to person. Arguments for and against faecal-oral, oral-oral and gastric-oral transmission have been presented, but the dominance of one of these routes is still to be determined.