Seroprevalence of Helicobacter pylori in a longitudinal study of New Zealanders at ages 11 and 21

Background: Helicobacter pylori seroprevalence increases with age in adult life but spontaneous reversion may occur in childhood and adolescence. Aims: To determine the seroprevalence of H. pylori in a longitudinal study of New Zealanders at ages 11 and 21. Methods: Serum from members of the Dunedin Multidisciplinary Health and Dev elopment Study (DMHDS) at age 11 (n=561; 303 males, 258 females) and 21 (n= 785; 413 males, 372 females) was tested for H. pylori antibodies. A large p roportion of those tested at age 11 was retested at age 21 (n=465; 262 male s, 203 females). Serological status was examined in terms of gender, socioe conomic status (SES) and self-reported use of antibiotics. Results: The seroprevalence of H. pylori decreased by 38% from 6.6% (37/561 ) at age 11 to 4.1% (32/785) at age 21. Seroprevalence at age 11 was not as sociated with gender or SES. For those tested at both ages, the drop in ser oprevalence from 6.7% to 4.1% was statistically significant (t=2.57, p<0.01 , paired t-test) and was much greater in females (71%) than males (12%). Of the 31 seropositive individuals at age 11, 17 (six males, 11 females) sero reverted and self-reported antibiotic use in the year preceeding age 21 was more common in females (eight/11) than males (zero/six). Of the 434 serone gative individuals at age 11, only five (four males, one female) had seroco nverted at age 21. Conclusions: Seroprevalence in the DMHDS declined from age 11 to 21 predomi nantly in females. The decline involved a greater rate of seroreversion and lower rate of seroconversion in females than males.