Respiratory infection, exposure to mouse allergen and breastfeeding: role in recurrent wheezing in early life.
BACKGROUND
Environmental factors may influence the development of allergen sensitization and asthma. The aim of this study was to evaluate the role of endotoxin and allergen exposure in early life as a risk factor for recurrent wheezing.


METHODS
One hundred and four infants from low-income families, at high risk of asthma, were enrolled at birth. Dust samples were collected from the bedding and bedroom floor within 6 months after birth. Recurrent wheezing was defined as 3 or more wheezing episodes in the past year. Endotoxin was determined by Limulus amebocyte lysate assay, and major indoor allergens were quantitated by ELISA in dust extracts. IgE antibodies were measured by ImmunoCAP at 30 months of age.


RESULTS
At 30 months, 51 of the 99 infants who completed the study (51.5%) had recurrent wheezing. Respiratory infection was strongly associated with recurrent wheezing (OR 6.67, 95% CI 1.96-22.72), whereas exclusive breastfeeding for at least 1 month was a protective factor (OR 0.09, 95% CI 0.01-0.51). Exposure to high levels of mouse allergen was more frequent among non-recurrent wheezers, approaching significance (OR 0.12, 95% CI 0.01-1.13; p = 0.064). None of the children were sensitized to mouse. Sensitization to mite was found in 26/90 (28.8%) children, with no association with recurrent wheezing.


CONCLUSIONS
Respiratory infection was strongly associated with recurrent wheezing in the first 30 months of life, in children at high risk of asthma, living in a socially deprived community in Brazil.
Division of Pediatric Allergy, Immunology and Rheumatology, Paulista School of Medicine, Federal University of São Paulo, São Paulo, Brazil.
Vera E V
VE
Rullo
L Karla
LK
Arruda
M Regina
MR
Cardoso
Vivien
V
Valente
Alessandra S
AS
Zampolo
Fernando
F
Nóbrega
Charles K
CK
Naspitz
Dirceu
D
Solé
D000485:Allergens / Q000032:analysis / Q000276:immunology*; D039741:Antigens, Dermatophagoides / Q000032:analysis; D052179:Antigens, Plant; D060829:Arthropod Proteins; D001512:Bedding and Linens; D001938:Brazil / Q000453:epidemiology; D001942:Breast Feeding / Q000706:statistics & numerical data*; D003546:Cysteine Endopeptidases; D004391:Dust / Q000032:analysis / Q000276:immunology; D004731:Endotoxins / Q000032:analysis; D004781:Environmental Exposure / Q000032:analysis*; D005260:Female; D005430:Floors and Floorcoverings; D006023:Glycoproteins / Q000032:analysis; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology; D007231:Infant, Newborn; D008297:Male; D011203:Poverty; D011446:Prospective Studies; D012135:Respiratory Sounds / Q000209:etiology*; D012141:Respiratory Tract Infections / Q000150:complications* / Q000453:epidemiology; D012307:Risk Factors; D012882:Skin Tests
D000485:Allergens; D039741:Antigens, Dermatophagoides; D052179:Antigens, Plant; D060829:Arthropod Proteins; D004391:Dust; D004731:Endotoxins; D006023:Glycoproteins; C518791:Mus m 1 allergen, Mus musculus; C105482:allergen Bla g 1; C091462:allergen Can f I; C091463:allergen Per a I; D007073:Immunoglobulin E; D003546:Cysteine Endopeptidases; C451159:Dermatophagoides farinae antigen f 1; C451162:Dermatophagoides pteronyssinus antigen p 1; C059296:Fel d 1 protein, Felis domesticus