Seroprevalence of Helicobacter pylori infections in a cohort of US Army recruits.

To study the prevalence and risk factors of Helicobacter pylori infection in healthy young adults, sera were collected from a nationwide sample of 404 females and 534 males (mean age, 20.2; range, 17-26 years) at induction into the US Army at Fort Jackson, South Carolina, during the fall of 1990. An enzyme-linked immunosorbent assay (PYLORI STAT, BioWhittaker, Inc., Walkersville, MD) was used to detect H. pylori-specific immunoglobulin G antibodies. Demographic data were obtained from a personnel database and by linking US census information to the subject's home address. The observed crude seropositivity rate was 26.3% (95% confidence interval 23.2-28.9). The direct sex-, race-, and geographic region-adjusted seropositivity rate was 20.8% (95% confidence interval 17.9-23.7). Seropositivity rates for blacks, Hispanics, and whites were 44%, 38%, and 14%, respectively, (chi 2, p < 0.001), and rates increased progressively from 24% in the age group 17-18 years to 43% in the age group 24-26 years (chi 2 for trend, p < 0.001). The age trends remained strong after controlling for race Median income was also an important predictive variable for seropositivity (chi 2, p < 0.0001). Sex, the percent urbanization, and population density of the home county were not significant predictors of seropositivity when age and race-ethnic group were controlled in a statistical model. The sharp increase in seroprevalence in this narrow age range suggests that the incidence rates are higher in young adults than previously reported.