Risk factors and immunological pathways for asthma and other allergic diseases in children: background and methodology of a longitudinal study in a large urban center in Northeastern Brazil (Salvador-SCAALA study)

Abstract

BackgroundThe prevalence of asthma and allergic diseases has increased in industrialised countries, and it is known that rates vary according whether the area is urban or rural and to socio-economic status. Surveys conducted in some urban settings in Latin America found high prevalence rates, only exceeded by the rates observed in industrialised English-speaking countries. It is likely that the marked changes in the environment, life style and living conditions in Latin America are responsible for these observations. The understanding of the epidemiological and immunological changes that underlie the increase in asthma and allergic diseases in Latin America aimed by SCAALA studies in Brazil and Ecuador will be crucial for the identification of novel preventive interventions.Methods/DesignThe Salvador-SCAALA project described here is a longitudinal study involving children aged 4–11 years living in the city of Salvador, Northeastern Brazil. Data on asthma and allergic diseases (rhinitis and eczema) and potential risk factors will be collected in successive surveys using standardised questionnaire. This will be completed with data on dust collection (to dust mite and endotoxin), skin test to most common allergens, stool examinations to helminth and parasites, blood samples (to infection, total and specific IgE, and immunological makers), formaldehyde, physical inspection to diagnoses of eczema, and anthropometric measures. Data on earlier exposures when these children were 0–3 years old are available from a different project.DiscussionIt is expected that knowledge generated may help identify public health interventions that may enable countries in LA to enjoy the benefits of a "modern" lifestyle while avoiding – or minimising – increases in morbidity caused by asthma and allergies.

Overweight, asthma symptoms, atopy and pulmonary function in children of 4–12 years of age: findings from the SCAALA cohort in Salvador, Bahia, Brazil

“…Saline solution and histamine were used as negative and positive controls, respectively (18) . The size of the skin wheal reaction was read after 15 min and the test was considered positive if the mean of the two perpendicular diameters (excluding the erythema and pseudopods) was $3 mm larger than that of negative controls.…”

Use of prescribed and non-prescribed medications among children living in poor areas in the city of Salvador, Bahia State, Brazil

“…This study forms part of a larger project carried out in Salvador on the risk factors for asthma and allergies in children (SCAALA) 24 .…”

“…The characteristics of the cohort were described in a previous study 24 . The study population was selected from a sample of children residing in 24 micro-areas representing the poorest regions in Salvador.…”

“…The first survey was conducted between 2000 and 2002, with the aim of assessing the impact of a sanitation program on the health of children aged 0-4 years 25 . This cohort was also studied in a second epidemiological survey of risk factors for asthma and allergies conducted in 2005, which characterized the population covered by the SCAALA project 24 . Thus, during the period of home interviews in 2006, 1,382 children aged 4-11 years participated in the study, comprising 95.6% of the initial cohort of the SCAALA project (1,445 children) 24 .…”

Distribuição da gravidade da asma na infância

“…10 For purposes of agreement analysis, the moderate and severe asthma categories of the GINA questionnaire were collated into a single "severe" category, whereas intermittent and provided positive responses to questions assessing symptom severity, whereas 307 (77.3%) replied in the negative.…”