title: Seroprevalence of Helicobacter pylori in a longitudinal study of New Zealanders at ages 11 and 21.
abstract: BACKGROUND
  Helicobacter pylori seroprevalence increases with age in adult life but spontaneous reversion may occur in childhood and adolescence.
  
  
  OBJECTIVE
  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 Development 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 proportion of those tested at age 11 was retested at age 21 (n = 465; 262 males, 203 females). Serological status was examined in terms of gender, socioeconomic 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 associated with gender or SES. For those tested at both ages, the drop in seroprevalence 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) seroreverted 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 seronegative individuals at age 11, only five (four males, one female) had seroconverted at age 21.
  
  
  CONCLUSIONS
  Seroprevalence in the DMHDS declined from age 11 to 21 predominantly in females. The decline involved a greater rate of seroreversion and lower rate of seroconversion in females than males.
authors.affiliation: School of Pharmacy, University of Otago, Dunedin, New Zealand.
authors.forename: J P
authors.initials: JP
authors.lastname: Fawcett
authors.forename: J P
authors.initials: JP
authors.lastname: Shaw
authors.forename: M
authors.initials: M
authors.lastname: Brooke
authors.forename: A
authors.initials: A
authors.lastname: Walker
authors.forename: G O
authors.initials: GO
authors.lastname: Barbezat
mesh_terms: D000293:Adolescent; D000328:Adult; D000907:Antibodies, Bacterial / Q000032:analysis*; D002648:Child; D005260:Female; D016481:Helicobacter Infections / Q000453:epidemiology*; D016480:Helicobacter pylori / Q000276:immunology*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009520:New Zealand / Q000453:epidemiology; D016036:Seroepidemiologic Studies
chemical_list: D000907:Antibodies, Bacterial