Routes of transmission of Helicobacter pylori infection

Helicobacter pylori is an important gastroduodenal pathogen, which has been recognized as a Class I carcinogen factor for gastric cancer and gastric mucosa associated lymphoid tissue lymphomas. In spite of the world-wide spread of the infection, the route of transmission is still not known. We reviewed data from several sero-epidemiological studies and aimed to identify potential sources of Helicobacter pylori infection. Available evidence strongly suggests an inverse correlation between socio-economic status and prevalence of Helicobacter pylori. The infection is acquired mostly during childhood in the third world, but is rare in children in developed countries, where the prevalence of Helicobacter pylori increases with age. Following the detection of the bacterium in saliva, faeces, and gastric juice, oral-oral or faecal-oral transmission and iatrogenic spread, through the use of unsterile endoscopes, have been proposed as possible routes of infection. Helicobacter pylori has also been found in some domestic cats, but at present, the risk of infection from these animals appears slight. The mode of transmission of Helicobacter pylori, as is yet, not known. Available information support the hypothesis of spread through close personal contact, considering humans as the only significant reservoir of infection.