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Background: In Brazil, studies evaluating the prevalence of asthma and allergic diseases among children living in rural area compared to urban area are rare. Some authors identified as risk factors for higher prevalence of current wheezing to have a family history of asthma, to have contact with pets, and being student in an urban school. The International Study of Asthma and Allergies in Childhood (ISAAC) phase 3 has shown higher prevalence of wheezing, nasal symptoms and cutaneous rash in the last 12 months in centers from Northern (N) and Northeastern (NE) regions of Brazil., Objective: To evaluate if adolescents with similar genetic background, living in a rural area are protected against the development of symptoms of asthma, rhinitis, and atopic eczema when compared to those living in an urban area in the same region of the country., Subjects and Method: Adolescents (13-14 year-old) living in Caruaru (Pernambuco) and in Santa Maria (Rio Grande do Sul) were enrolled in this study (2002-2003). The adolescents filled in the ISAAC written questionnaire (WQ), previously translated and validated to the Brazilian culture (30-32). Data obtained were transcribed manually into a database (Epi-Info) supplied by ISAAC's coordinators and were statistically analyzed by the SSPS-12 software., Results: The prevalence of asthma related symptoms were higher among those adolescents living in the urban centers in comparison to the rural ones. These differences were significant for wheezy ever, wheezy in the last 12 months, asthma ever, and wheezy with exercise in Caruaru and for wheezy ever and asthma ever, in Santa Maria. Comparing urban areas, the prevalence of asthma related symptoms in Caruaru was higher than in Santa Maria, except for wheezy ever and wheezy with exercise. The opposite was observed comparing rural areas: the prevalence of asthma (except for nocturnal cough) was higher in Santa Maria despite lesser severity of symptoms in this city.

The present study is aimed to describe the changes in the prevalence of symptoms of asthma, rhinitis and eczema among Brazilian adolescents (AD, 13-14 years old) between Phases 1 and 3 of the International Study of Asthma and Allergies in Childhood (ISAAC). The prevalence of self-reported symptoms of asthma, rhinitis and eczema in AD from five Brazilian cities (Curitiba, Porto Alegre, Recife, Salvador and São Paulo), obtained during ISAAC Phase 1 (n = 15 419) and Phase 3 (n = 15 684), was compared to determine the trend of prevalence in a 7-year interval. There was a trend to reduction in the current prevalence of wheezing and increasing of nocturnal cough when averaging figures from the five cities. The prevalence of wheezing in the last 12 months was 27.7 vs. 19.9% (p < 0.01); asthma ever 14.9 vs. 14.7% (p > 0.05); severe episode of wheezing 5.2 vs. 5.2%; nocturnal cough 32.6 vs. 34.9% (p < 0.01); exercise wheezing 23.6 vs. 23.0% (p > 0.05) and awake with wheezing 11.8 vs. 11.2% (p > 0.05). Similar things were observed with the prevalence of current symptoms of rhinitis and eczema. In Brazil, there was a small but significant mean decrease in the prevalence of two asthma-related symptoms, wheezing and nocturnal cough, though this trend was not consistent in the surveyed cities. The prevalence of asthma symptoms in Brazil, despite its mean trend to a decrease, is still one of the highest in Latin America.

Objectives: To evaluate the relationship between exposure to gaseous air pollutants (ozone [O3], carbon monoxide [CO], nitrogen dioxide [NO2], and sulfur dioxide [SO2]) socioeconomic status and the prevalence of symptoms of asthma, rhinitis and atopic eczema in adolescents., Subjects and Methods: A sample of 16 209 adolescents from São Paulo West (SPW), São Paulo South (SPS), Santo André (SA), Curitiba (CR), and Porto Alegre (PoA) were enrolled. Data on air pollutants and socioeconomic status were compared to prevalence of symptoms with the Spearman correlation coefficient., Results: Socioeconomic status was quite similar in all cities. The levels of O3 in SPW, SPS, and SA, and of CO in SA were higher than the acceptable ones. In relation to O3 and CO exposures, adolescents from SPW and SA had a significant risk of current wheezing, whereas living in SPW was associated with a high risk of rhinoconjunctivitis, eczema, and flexural eczema and living in CR to rhinitis. Exposure to NO2 was associated with a high risk of current wheezing in SPW and SA, and of severe asthma in SPW and PoA. Exposure to SO2 was associated with a high risk of current wheezing in SPW and SA, severe asthma in SPW and PoA, and nighttime cough, eczema, flexural eczema and severe eczema in SPW. Living in SPW, CR, or PoA was associated with a high risk of rhinitis, rhinoconjunctivitis, and severe rhinitis., Conclusions: Although we did not detect a characteristic pattern for all symptoms evaluated or a specific air pollutant, our data suggest a relationship between higher exposure to photochemical pollutants and high prevalence or risk of symptoms of asthma, rhinitis, and atopic eczema.

By using the standard written questionnaire (WQ), designed for the International Study of Asthma and Allergies in Childhood (ISAAC) we determined the prevalence of rhinitis and its related-symptoms, in Brazilian children and adolescents, living in different cities of the country. The WQ was answered by the parents of 11,403 children aged 6-7 years from five Brazilian cities: Porto Alegre (South, N = 2,846), São Paulo (Southeast, N = 3,005) Uberlândia (Southeast, N = 2,991), Itabira (Southeast, N = 1,151) and Recife (Northeast, N = 1,410). The WQ was also applied to 20,587 adolescents (13-14 years old) living in: Porto Alegre (South, N = 3,195), Curitiba (South, N = 3,004), São Paulo (Southeast, N = 3,008), Uberlândia (Southeast, N = 2,998), Itabira (Southeast, N = 2,134), Salvador (Northeast, N = 3,162) and Recife (Northeast, N = 3,086). The mean response rates were 75% and 95%, for the 6-7 year-old children and for the adolescents, respectively. The data was transcribed to a database (Epi-Info) and analyzed regarding the answers to questions of rhinitis module. The mean prevalence of rhinitis (affirmative response to question 2) was 26.6% and 34.2% in the groups of 6-7 and 13-14 year-old, respectively. Applying the criteria that evaluate the association between nasal and ocular symptoms (affirmative response to question 3) the mean prevalence of allergic rhinitis were 12.8% for the 6-7 year-old children and 18.0% for the adolescents. In conclusion, the prevalence of rhinitis and its related symptoms among children and adolescents living in different Brazilian cities was as high as the prevalence observed in other areas of the world.