title: [The effects of a rural environment on the prevalence of allergic rhinitis among schoolchildren in Mexicali, Baja California, Mexico].
abstract: OBJECTIVE
  To assess the prevalence of allergic rhinitis symptoms among schoolchildren in Mexicali, Baja California, Mexico, and determine what impact a rural environment might have on this condition.
  
  
  METHODS
  A population-based, cross-sectional study using a standardized questionnaire administered to a random sample of 2087 schoolchildren 6-7 years of age (1078 girls and 1009 boys) living in the city of Mexicali, Baja California, Mexico. The study analyzed associations between exposure variables and personal and family health history, and two dependent variables-nasal symptoms and nasal and ocular symptoms, in the absence of a cold or flu-using odd ratios (OR) and 95% Confidence Intervals (95%CI). The study took place in February-July 2004 and followed the methodology of the International Study of Asthma and Allergies in Childhood (ISAAC).
  
  
  RESULTS
  The general prevalence of nasal symptoms and nasal and ocular symptoms was 25.0% and 10.5%, respectively. The boys and girls who had ever lived on a farm or in a rural area had a lower probability, adjusted for confounding variables, of presenting nasal symptoms (OR=0.43; 95%CI: 0.24-0.77), or nasal and ocular symptoms (OR=0.39; 95%CI: 0.16-0.93).
  
  
  CONCLUSIONS
  In the study population, exposure to a rural environment in early childhood decreased the risk of developing allergic rhinitis, regardless of a family history of asthma.
authors.affiliation: Instituto Nacional de Salud Pública, Cuernavaca, Morelos, Mexico.
authors.forename: Claudia
authors.initials: C
authors.lastname: Bäcker
authors.forename: Albino
authors.initials: A
authors.lastname: Barraza-Villarreal
authors.forename: Hortensia
authors.initials: H
authors.lastname: Moreno-Macías
authors.forename: Consuelo
authors.initials: C
authors.lastname: Escamilla-Núñez
authors.forename: Isabelle
authors.initials: I
authors.lastname: Romieu
mesh_terms: D002648:Child; D003430:Cross-Sectional Studies; D004777:Environment; D005260:Female; D006801:Humans; D008297:Male; D008800:Mexico / Q000453:epidemiology; D015995:Prevalence; D012221:Rhinitis, Allergic, Perennial / Q000453:epidemiology*; D006255:Rhinitis, Allergic, Seasonal / Q000453:epidemiology*; D012424:Rural Population