Efecto del ambiente rural sobre la prevalencia de rinitis alérgica en escolares de Mexicali, Baja California, México

objectives: 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 2 087 schoolchildren 6-7 years of age (1 078 girls and 1 009 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.