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Acevedo et al. BMC Pulmonary Medicine 2012, 12:13 http://www.biomedcentral.com/1471-2466/12/13

RESEARCH ARTICLE

Open Access

Particular characteristics of allergic symptoms in tropical environments: follow up to 24 months in the FRAAT birth cohort study
Nathalie Acevedo1,2, Jorge Sánchez1,2, Josefina Zakzuk1,2, Adriana Bornacelly1,2, Carlos Quiróz1, Álvaro Alvarez3, Marta Puello3, KettyMendoza3, Dalgys Martínez1,2, Dilia Mercado1, Silvia Jiménez1,2 and Luis Caraballo1,2*

Abstract
Background: Early wheezing and asthma are relevant health problems in the tropics. Mite sensitization is an important risk factor, but the roles of others, inherent in poverty, are unknown. We designed a birth-cohort study in Cartagena (Colombia) to investigate genetic and environmental risk factorsfor asthma and atopy, considering as particular features perennial exposure to mites, parasite infections and poor living conditions. Methods: Pregnant women representative of the low-income suburbs of the city were randomly screened for eligibility at delivery; 326 mother-infant pairs were included at baseline and biological samples were collected from birth to 24 months for immunologicaltesting, molecular genetics and gene expression analysis. Pre and post-natal information was collected using questionnaires. Results: 94% of families were from the poorest communes of the city, 40% lacked sewage and 11% tap-water. Intestinal parasites were found as early as 3 months; by the second year, 37.9% of children have had parasites and 5.22% detectable eggs of Ascaris lumbricoides in stools(Median 3458 epg, IQR 975-9256). The prevalence of “wheezing ever” was 17.5% at 6 months, 31.1% at 12 months and 38.3% at 24 months; and recurrent wheezing (3 or more episodes) 7.1% at 12 months and 14.2% at 24 months. Maternal rhinitis [aOR 3.03 (95%CI 1.60-5.74), p = 0.001] and male gender [aOR 2.09 (95%CI 1.09 - 4.01), p = 0.026], increased risk for wheezing at 6 months. At 24 months, maternalasthma was the main predisposing factor for wheezing [aOR 3.65 (95%CI 1.23-10.8), p = 0.01]. Clinical symptoms of milk/egg allergy or other food-induced allergies were scarce (1.8%) and no case of atopic eczema was observed. Conclusions: Wheezing is the most frequent phenotype during the first 24 months of life and is strongly associated with maternal asthma. At 24 months, the natural history ofallergic symptoms is different to the “atopic march” described in some industrialized countries. This cohort is representative of socially deprived urban areas of underdeveloped tropical countries. The collection of biological samples, data on exposure and defined phenotypes, will contribute to understand the gene/environment interactions leading to allergy inception and evolution. Keywords: Birthcohort study, Wheezing, Allergy, Asthma, Rhinitis, Eczema, Atopic march, The tropics, Parasite, Poverty, Cartagena, Latin America

* Correspondence: caraballo@fundemeb.org 1 Institute for Immunological Research, University of Cartagena, Cartagena, Colombia Full list of author information is available at the end of the article
© 2012 Acevedo et al; licensee BioMed Central Ltd. This is an Open Accessarticle distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Acevedo et al. BMC Pulmonary Medicine 2012, 12:13 http://www.biomedcentral.com/1471-2466/12/13

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Background The causes of asthmaand other allergic diseases remain unknown. Genetic and epidemiological studies suggest that for these multifactorial diseases the expression of different phenotypes depend on complex interactions between susceptibility genes and the environment [1]. This is reflected in the wide differences in prevalence and natural history of allergic diseases around the world [2]. In many regions of Latin...