title: Does previous infection protect against atopic eczema and recurrent wheeze in infancy?
abstract: BACKGROUND
  Frequent infection in infancy and early childhood has been hypothesized to explain the low prevalence of asthma and other atopic disease among children in developing countries (the so-called 'hygiene hypothesis'), but the low prevalence in Eastern Europe remains unexplained.
  
  
  OBJECTIVE
  To test the hygiene hypothesis in the Republic of Belarus by examining the relationship between gastrointestinal (GI) and respiratory infection and two potentially atopic outcomes in the first 12 months of life: atopic eczema and recurrent wheeze. METHODS; We carried out two case-control studies nested within a large (n=17 046) randomized trial in Belarus, with cases defined as (1) first occurrence of atopic eczema (n=819) and (2) second episode of wheezing (n=112). Incidence density sampling was used to select four matched controls born within 1 month at the same hospital as the case. Exposure was defined as one or more episodes of GI or respiratory infection (examined separately) with onset >7 days before onset of the case's atopic outcome. Analyses controlled for family atopic history, duration of exclusive breastfeeding, sex, birth weight, maternal education, and (for recurrent wheeze) maternal smoking.
  
  
  RESULTS
  For atopic eczema, prior GI infection occurred in 7.4% of cases vs. 6.0% of controls [adjusted OR=1.27 (0.94-1.72)] and prior respiratory infection in 35.2% vs. 32.6% [adjusted OR=1.14 (95% CI=0.94-1.37)]. For recurrent wheeze, prior GI infection occurred in 9.8% of cases vs. 7.4% of controls [adjusted OR=1.30 (0.60-2.82)].
  
  
  CONCLUSIONS
  Our results do not support the hypothesis that infection protects against atopic eczema or recurrent wheezing in the first 12 months of life.
authors.affiliation: Department of Pediatrics, McGill University Faculty of Medicine, Montreal, Canada. michael.kramer@mcgill.ca
authors.forename: M S
authors.initials: MS
authors.lastname: Kramer
authors.forename: T
authors.initials: T
authors.lastname: Guo
authors.forename: R W
authors.initials: RW
authors.lastname: Platt
authors.forename: Z
authors.initials: Z
authors.lastname: Sevkovskaya
authors.forename: I
authors.initials: I
authors.lastname: Dzikovich
authors.forename: J-P
authors.initials: JP
authors.lastname: Collet
authors.forename: S
authors.initials: S
authors.lastname: Shapiro
authors.forename: B
authors.initials: B
authors.lastname: Chalmers
authors.forename: E
authors.initials: E
authors.lastname: Hodnett
authors.forename: I
authors.initials: I
authors.lastname: Vanilovich
authors.forename: I
authors.initials: I
authors.lastname: Mezen
authors.forename: T
authors.initials: T
authors.lastname: Ducruet
authors.forename: G
authors.initials: G
authors.lastname: Shishko
authors.forename: N
authors.initials: N
authors.lastname: Bogdanovich
mesh_terms: D000328:Adult; D001424:Bacterial Infections / Q000150:complications* / Q000276:immunology; D001942:Breast Feeding; D016022:Case-Control Studies; D003876:Dermatitis, Atopic / Q000276:immunology / Q000517:prevention & control*; D019049:Developed Countries; D005260:Female; D005759:Gastroenteritis / Q000150:complications / Q000276:immunology; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D008297:Male; D002094:Republic of Belarus; D012130:Respiratory Hypersensitivity / Q000276:immunology / Q000517:prevention & control*; D012135:Respiratory Sounds; D012141:Respiratory Tract Infections / Q000150:complications / Q000276:immunology