Persistent and transient Helicobacter pylori infections in early childhood.

BACKGROUND Helicobacter pylori, the main cause of peptic ulcer disease and gastric cancer in adult populations, is generally acquired during the first years of life. Infection can be persistent or transient and bacterial and host factors determining persistence are largely unknown and may prove relevant for future disease. METHODS Two cohorts of healthy Chilean infants (313 total) were evaluated every 3 months for 18-57 months to determine pathogen- and host-factors associated with persistent and transient infection. RESULTS One-third had at least one positive stool ELISA by age 3, with 20% overall persistence. Persistent infections were acquired at an earlier age, associated with more household members, decreased duration of breastfeeding, and nonsecretor status compared to transient infections. The cagA positive strains were more common in persistent stools, and nearly 60% of fully characterized persistent stool samples amplified cagA/vacAs1m1. Persistent children were more likely to elicit a serologic immune response, and both infection groups had differential gene expression profiles, including genes associated with cancer suppression when compared to healthy controls. CONCLUSIONS These results indicate that persistent H. pylori infections acquired early in life are associated with specific host and/or strain profiles possibly associated with future disease occurrence.