Background: Helicobacter pylori infection is common worldwide, but the time of acquisition is unclear. We investigated this issue in a cohort of children selected retrospectively from a population followed up for 21 years.
Methods: We monitored 224 children (99 black, 125 white; 110 male, 114 female) from 1975-76 (ages 1-3 years) to 1995-96. H pylori status was assessed by presence of serum IgG antibodies.
Findings: 18 (8.0%) children at age 1-3 years had H pylori antibodies (13% black vs 4% white children, p=0.008). By age 18-23 years, the prevalence of the infection was 24.5% (43% black vs 8% white participants, p< 0.0001). Of the 206 children not infected at baseline, 40 (19%) became infected by age 21-23. The crude incidence rate per year was 1.4% for the whole cohort, ranging from 2.1% at 4-5 years and 1.5% at age 7-9 years to 0.3% at 21-23 years. The seroconversion rate was higher among black than among white children (relative risk 3.3, 95% CI 1.8-6.2, p=0.001). The median age for seroconversion was 7.5 years for both races. Nine of the 58 seropositive children cleared the infection during follow-up. The rate of seroreversion per year was 1.1%; it was highest among children at age 4-5 years (2.2% vs 0.2% at ages 18-19).
Interpretation: Most newly acquired H pylori infections happened before age 10 years. Treatment and preventive strategies should be aimed at children in this age-group.