title: Environmental risk factors in the first year of life and childhood asthma in the Central South of Chile.
abstract: BACKGROUND
  Childhood asthma has a high prevalence in South America--a region of the world currently undergoing a thorough modernization and transition process. Asthma in South America is mainly associated with poor urban environment, which actually may challenge the role of the hygiene hypothesis. We systematically assessed the impact of environmental factors in the first year of life on asthma.
  
  
  METHODS
  A case-control study including 188 asthmatics and 294 hospital-based controls aged 6-15 years was carried out in the Central South of Chile. Parents of study participants completed a computer-assisted interview on environmental factors (such as birth order, day-care attendance, pneumonia infection, regular animal and furry pet contact, and environmental tobacco smoke exposure) in the first year of life and potential confounders. Atopy was assessed using skin prick tests. Multivariate logistic regression models were calculated to assess the association between exposures and asthma, adjusting for potential confounders.
  
  
  RESULTS
  Day-care attendance (OR = 0.31; 95% CI: 0.10, 0.94) and regular farm animal contact (OR = 0.38; 95% CI: 0.17, 0.85) were inversely related to childhood asthma in the logistic regression models. Pneumonia infection (OR = 2.24; 95% CI: 1.21, 4.16) and mold or dampness in the home (OR = 1.87; 95% CI: 1.18, 2.97) in the first year of life were positively associated with asthma.
  
  
  CONCLUSIONS
  Our results suggest that the hygiene hypothesis is also applicable in the Chilean setting, a South American country in epidemiological transition.
authors.affiliation: Unit for Occupational and Environmental Epidemiology, Institute and Outpatient Clinic for Occupational, Social and Environmental Medicine, University Hospital of Munich, Munich, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Boneberger
authors.forename: Daniel
authors.initials: D
authors.lastname: Haider
authors.forename: Jennifer
authors.initials: J
authors.lastname: Baer
authors.forename: Leonie
authors.initials: L
authors.lastname: Kausel
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Von Kries
authors.forename: Michael
authors.initials: M
authors.lastname: Kabesch
authors.forename: Katja
authors.initials: K
authors.lastname: Radon
authors.forename: Mario
authors.initials: M
authors.lastname: Calvo
mesh_terms: D000293:Adolescent; D017668:Age of Onset; D001249:Asthma / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D016022:Case-Control Studies; D002648:Child; D002677:Chile / Q000453:epidemiology; D016001:Confidence Intervals; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007223:Infant; D016015:Logistic Models; D008297:Male; D016017:Odds Ratio; D012141:Respiratory Tract Infections / Q000175:diagnosis / Q000453:epidemiology; D012307:Risk Factors; D012720:Severity of Illness Index; D017678:Sex Distribution; D014028:Tobacco Smoke Pollution / Q000009:adverse effects / Q000706:statistics & numerical data
chemical_list: D014028:Tobacco Smoke Pollution