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).

BACKGROUND: The 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/DESIGN: The 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. DISCUSSION: It 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.

Peridomestic risk factors for canine leishmaniasis in urban dwellings: new findings from a prospective study in Brazil.

Despite the wealth of information on the prevalence and correlates of canine Leishmania infection (CLI), data on its incidence are still sparse, and little is known regarding risk factors for CLI. We studied a cohort of dogs in an urban area in Brazil to determine whether incidence varied with age, breed, and environmental characteristics. The mean follow-up was 1.5 years, and the crude incidence rate was 11.8 cases/100 dog-years (95% confidence interval [CI] = 8.6-15.6). In the multivariate analysis, short fur was the strongest predictor of CLI (relative risk [RR] = 9.4). In addition, our data indicate that raising pigs (RR = 4.1), chickens (RR = 3.3), or other livestock (RR = 2.6) significantly increased the risk of CLI. Thus, suggesting control measures directed towards modifying the environmental factors favoring contact between vectors, reservoirs, and susceptible humans, such as proximity to pigpens or hen houses. Furthermore, conventional control programs of insecticidal spraying of human dwellings should also apply insecticide in and around animal sheds.