Seroepidemiological study of Helicobacter pylori infection in infancy.

The incidence of Helicobacter pylori infection in very young children was determined, based on the emergence of specific IgG antibodies in sequential serum samples from birth to 2 years of age. The risk of acquiring H pylori infection in infancy as a result of maternal exposure to the organism was also assessed, based on the determination of maternal cord-blood antibodies. Serum IgG class H pylori antibodies were analysed in the cord blood samples of 195 newborns and in their follow up samples until the age of 2 years. Maternal antibodies were detected in the cord-blood samples of 21 children (10.6%). These antibodies disappeared in all but one child before 7 months of age and no new seroconversions occurred in these children. Ten originally cord-blood negative children seroconverted up to the age of 2 years (5.1%). It is concluded that a major proportion of H pylori infections observed in young adults in Finland are acquired during the first two years of life. Maternal seropositivity is not a straightforward risk factor for acquiring H pylori infection in infancy.