Helicobacter pylori infection among Japanese children.

BACKGROUND: In Japan, there are few reports describing Helicobacter pylori infection among young children. The aim of the present study was to identify risk factors associated with H. pylori in school-aged children.
METHODS: Subjects were first-grade students of three elementary schools (n = 310) and second-grade students of a junior high school (n = 300). Personal information, such as student's medical history, parent's history, family size, sibshipsize and household pets, was collected from guardians using a questionnaire. Saliva samples and personal information were collected twice (1995 and 1996). By using the saliva samples, H. pylori IgG antibody was measured using a commercial kit. To analyze the risk factors for H. pylori infection, sex- and age-adjusted odds ratios (OR) were calculated using a multiple logistic model.
RESULTS: Among the children, factors related to Helicobacter antibody in saliva included spending a longer period of time in a nursery school or kindergarten (OR = 4.0) and a maternal history of stomach disease (OR = 2.8). Birth order (OR = 2.2), sleeping situation (OR = 2.3) and sibshipsize (OR = 1.6) were not factors that were significantly related to Helicobacter antibody in the saliva. Chewing food for the infant, family size, rooms in the household, sharing a bedroom during childhood, pets, a past history and a paternal history were not related to positivity.
CONCLUSIONS: The results indicate that transmission is person-to-person, mainly through close contact with other children and intrafamilial infection. Helicobacter pylori infection seems to occur frequently early in life, probably before 6 years of age.