Incidence of respiratory and allergic symptoms in Italian and immigrant children

Background: Immigration usually implies a complete change of the environment where one lives. Hence, studies on immigrants may help to disentangle genetic and environmental determinants of disease. We investigated whether the incidence of allergic and respiratory symptoms differed for Italian and immigrant children living in one area of Northern Italy. Methods: In December 2006, all the children (3-14 years) living in the Viadana district were surveyed through a parental questionnaire (response rate = 99%, n = 3854). Retrospective incidences of several symptoms were compared across different ethnic groups. Results: Parental asthma, allergic rhinitis and eczema were less frequent in immigrant children than in Italian children. Wheezing and eczema incidences were lower in children born to foreign parents (especially if born abroad, incidence rate ratio (IRR) = 0.47, 95% CI: 0.26-0.82 and IRR = 0.43, 95% CI: 0.23-0.83, respectively), with respect to Italian children, while the occurrence of nasal allergies was similar among the ethnic groups. The greatest incidence of persistent cough/phlegm was observed in children born in Italy to foreign parents (IRR = 1.98, 95% CI: 1.06-3.71) and in children whose parents had chronic bronchitis (IRR = 2.57, 95% CI: 1.52-4.33). Conclusions: Considering the distribution of parental atopic diseases and the low disease prevalence in the immigrants' countries of origin, we suggest that nasal allergies may be more sensitive than wheezing or eczema to the change in the environment related to migration. Genetic or environmental factors clustered into families seem to have a role on chronic bronchitis. © 2010 Elsevier Ltd. All rights reserved