title: Particular characteristics of allergic symptoms in tropical environments: follow up to 24 months in the FRAAT birth cohort study.
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 factors for 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 immunological testing, 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, maternal asthma 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 of allergic 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.
authors.affiliation: Institute for Immunological Research, University of Cartagena, Cartagena, Colombia.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Acevedo
authors.forename: Jorge
authors.initials: J
authors.lastname: Sánchez
authors.forename: Josefina
authors.initials: J
authors.lastname: Zakzuk
authors.forename: Adriana
authors.initials: A
authors.lastname: Bornacelly
authors.forename: Carlos
authors.initials: C
authors.lastname: Quiróz
authors.forename: Álvaro
authors.initials: Á
authors.lastname: Alvarez
authors.forename: Marta
authors.initials: M
authors.lastname: Puello
authors.forename: Ketty
authors.initials: K
authors.lastname: Mendoza
authors.forename: Dalgys
authors.initials: D
authors.lastname: Martínez
authors.forename: Dilia
authors.initials: D
authors.lastname: Mercado
authors.forename: Silvia
authors.initials: S
authors.lastname: Jiménez
authors.forename: Luis
authors.initials: L
authors.lastname: Caraballo
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D001249:Asthma / Q000453:epidemiology / Q000276:immunology; D002675:Child, Preschool; D015331:Cohort Studies; D003105:Colombia / Q000453:epidemiology; D004485:Eczema / Q000453:epidemiology* / Q000209:etiology* / Q000276:immunology; D005260:Female; D006798:Housing; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009349:Nematode Infections / Q000453:epidemiology / Q000276:immunology; D011203:Poverty; D011247:Pregnancy; D015995:Prevalence; D011528:Protozoan Infections / Q000453:epidemiology / Q000276:immunology; D012135:Respiratory Sounds / Q000209:etiology* / Q000276:immunology*; D012221:Rhinitis, Allergic, Perennial / Q000276:immunology; D012307:Risk Factors; D012737:Sex Factors; D011795:Surveys and Questionnaires; D014329:Tropical Climate; D014505:Urban Population; D055815:Young Adult