Effects of environment on human cytokine responses during childhood in the tropics: role of urban versus rural residence.

Background: Environment may have a key role in the development of the immune system in childhood and environmental exposures associated with rural residence may explain the low prevalence of allergic and autoimmune diseases in the rural tropics. We investigated the effects of urban versus rural residence on the adaptive immune response in children living in urban and rural areas in a tropical region of Latin America.

Methods: We recruited school children in either rural communities in the Province of Esmeraldas or in urban neighborhoods in the city of Esmeraldas, Ecuador.

Risk factors for death in patients with severe asthma.

Objective: To identify risk factors for death among patients with severe asthma.

Methods: This was a nested case-control study. Among the patients with severe asthma treated between December of 2002 and December of 2010 at the Central Referral Outpatient Clinic of the Bahia State Asthma Control Program, in the city of Salvador, Brazil, we selected all those who died, as well as selecting other patients with severe asthma to be used as controls (at a ratio of 1:4).

Seroprevalence and risk factors for Toxocara infection in children from an urban large setting in Northeast Brazil.

Objectives: This study aimed to standardize an "in house" immunoassay to detect anti-Toxocara IgG antibodies in human serum to estimate the seroprevalence of Toxocara infection, and to identify its potential risk factors in children living in poor areas of Salvador, a large northeastern Brazilian city.

Methods: Parents of 1309 children answered a questionnaire containing possible risk factor for acquisition of this infection. Blood was collected and the presence of anti-Toxocara IgG antibodies was detected by indirect ELISA using T.

The effect of single and multiple infections on atopy and wheezing in children.

Background: The current epidemic of asthma and atopy has been explained by alterations in immune responses related to reduction in childhood infections. However, the findings of epidemiologic studies investigating the association between infection with atopy and asthma have been inconsistent.

Objective: We sought to investigate the effect of single or multiple infections (pathogen burden) on atopy and wheeze in urban children from Latin America.

Poverty, dirt, infections and non-atopic wheezing in children from a Brazilian urban center.

Background: The causation of asthma is poorly understood. Risk factors for atopic and non-atopic asthma may be different. This study aimed to analyze the associations between markers of poverty, dirt and infections and wheezing in atopic and non-atopic children.