EPIDEMIOLOGY OF HELICOBACTER-PYLORI INFECTION

The seroprevalence of Helicobacter pylori infection increases with age . Incidence rates in children are higher than in adults and are consis tent with a cohort effect reflecting primary infection during childhoo d. Preliminary data would suggest that horizontal transmission of infe ction may occur both in adults and in children. Occasionally, this may result in transient multiple infection, because the observation of mo saicism has to imply horizontal transfer of genetic information betwee n infecting strains of H. pylori. The very close association between H . pylori infection and socio-economic conditions in childhood means th at the possibility of confounding factors should be considered when st udying routes of transmission or assessing the extra-gastric consequen ces of infection. Future studies will clarify these important issues.