title: Dynamics of Helicobacter pylori infection in a US-Mexico cohort during the first two years of life.
abstract: BACKGROUND
  The Pasitos Cohort Study has followed children in El Paso, Texas and Ciudad Juarez, Mexico since 1998 to identify determinants of Helicobacter pylori infection. This paper describes patterns of acquisition and elimination of H. pylori infection in 468 children from birth to 24 months.
  
  
  METHODS
  Mothers were recruited during pregnancy at maternal-child clinics; children were targeted for follow-up examinations every 6 months after birth. H. pylori infection was detected using the 13C-urea breath test, corrected for age-dependent variation in CO2 production.
  
  
  RESULTS
  Test results were available for 359, 341, 269, and 215 children around target ages of 6, 12, 18, and 24 months, respectively. The person-time at risk of a first detectable infection was 7742 person-months; 128 first infections were detected, thus the incidence rate was 1.7% per month (95% confidence interval 1.4-2.0%). Rates were similar in boys and girls and on both sides of the border; evidence suggests, however, that this similarity could be due to selection bias. Among children with follow-up after a positive test, 77% tested negative at a later visit.
  
  
  CONCLUSIONS
  The initial acquisition of detectable H. pylori infection occurred at a rate of 20% per year among Pasitos Cohort children from birth to 24 months of age. A key finding, with implications for clinical, community health, and research settings, is that most of these infections did not persist. The transient nature of early H. pylori infection should be considered when designing research or contemplating therapeutic intervention for this age group.
authors.affiliation: University of Texas Health Science Center, School of Public Health, Houston, TX, USA. karen.goodman@ualberta.ca
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Goodman
authors.forename: Kathleen
authors.initials: K
authors.lastname: O'rourke
authors.forename: R Sue
authors.initials: RS
authors.lastname: Day
authors.forename: Constance
authors.initials: C
authors.lastname: Wang
authors.forename: Zhannat
authors.initials: Z
authors.lastname: Nurgalieva
authors.forename: Carl V
authors.initials: CV
authors.lastname: Phillips
authors.forename: Corinne
authors.initials: C
authors.lastname: Aragaki
authors.forename: Armando
authors.initials: A
authors.lastname: Campos
authors.forename: J Manuel
authors.initials: JM
authors.lastname: de la Rosa
mesh_terms: D001944:Breath Tests / Q000379:methods; D004812:Epidemiologic Methods; D005260:Female; D016481:Helicobacter Infections / Q000453:epidemiology*; D016480:Helicobacter pylori; D006798:Housing / Q000706:statistics & numerical data; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008800:Mexico / Q000453:epidemiology; D011379:Prognosis; D012008:Recurrence; D012075:Remission, Spontaneous; D012959:Socioeconomic Factors; D013781:Texas / Q000453:epidemiology