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 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.