[Epidemiological studies and mode of transmission of Helicobacter pylori infection]

Recent epidemiological reports of Helicobacter pylori (HP) reveal that HP is distributed among all populations in the world. The prevalence rate in the developed countries is generally, lower than that in the developing countries. The prevalence of HP increases with age both in the developed and the developing countries, reflecting a socioeconomic status; the poorer a population, the earlier is the age of infecting HP, resulting in the higher prevalence rate of HP. The epidemiological evidence indicates that person-to-person transmission of HP may occur, through either faecal-oral or oral-oral. Gastroendoscopy manipulation could be one of the transmission routes. In Japan, the prevalence above 40 years old was as high (70-80%) as that in the developing countries, whereas under 40 it was as low in the developed countries. This unique mode of prevalence in Japan may come from an ethnic background and requires further studies.