Objectives: Transmission routes of Helicobacter pylori (Hp) have been extensively studied, but many aspects remain unclear. This study explored the dynamics of multiplex Hp serology within regular families during a 36-month prospective follow-up.

Methods: Altogether, 329 families from the Finnish Family HPV study were subjected to sequential blood sampling and now tested also for six Hp proteins, HP0010, HP0073, HP0547, HP0875, HP0887, and HP1564, using multiplex serology assay.

Results: Hp seropositivity, defined as being seropositive to at least three of the six Hp proteins, was more common among the fathers (20%) than mothers (10%). After maternal antibody decay, only a few children tested Hp-seropositive at later follow-up visits, indicating that acquisition of Hp infection is practically non-existent (0.4-2.0%) at an early age. No evidence was found to support the person-to-person transmission of Hp in this cohort because there was no correlation in Hp seropositivity or antibody levels between the spouses and/or their offspring, and individuals who were Hp-seropositive did not seem to increase the risk of other family members to co-test Hp-seropositive.

Conclusions: Our results perfectly agree with a recently published register-linkage study from Finland, where Hp and Hp-related co-morbidity are predicted to disappear among the native Finns during the 21^st century.