Risk factors for wheezing in a subtropical environment: role of respiratory viruses and allergen sensitization.
BACKGROUND
Risk factors for acute wheezing among children in subtropical areas are largely unknown.


OBJECTIVE
To investigate the role of viral infections, allergen sensitization, and exposure to indoor allergens as risk factors for acute wheezing in children 0 to 12 years old.


METHODS
One hundred thirty-two children 0 to 12 years of age who sought emergency department care for wheezing and 65 children with no history of wheezing were enrolled in this case-control study. Detection of respiratory syncytial virus antigen, rhinovirus and coronavirus RNA, adenovirus, influenza, and parainfluenza antigens was performed in nasal washes. Total IgE and specific IgE to mites, cockroach, cat, and dog were measured with the CAP system. Major allergens from mites, cockroach, cat, and dog were quantified in dust samples by ELISA. Univariate and multivariate analyses were performed by logistic regression.


RESULTS
In children under 2 years of age, infection with respiratory viruses and family history of allergy were independently associated with wheezing (odds ratio, 15.5 and 4.2; P = .0001 and P = .008, respectively). Among children 2 to 12 years old, sensitization to inhalant allergens was the major risk factor for wheezing (odds ratio, 2.7; P = .03). High-level allergen exposure, exposure to tobacco smoke, and lack of breast-feeding showed no association with wheezing.


CONCLUSIONS
Some risk factors for wheezing previously identified in temperate climates were present in a subtropical area, including respiratory syncytial virus infection in infants and allergy in children older than 2 years. Rhinovirus was not associated with wheezing and did not appear to be a trigger for asthma exacerbations.
Department of Pediatrics, School of Medicine of Ribeirão Preto, University of São Paulo, Brazil.
Ataide A
AA
Camara
Jorgete M
JM
Silva
Virginia P L
VP
Ferriani
Kátia R C
KR
Tobias
Izolete S
IS
Macedo
Márcio A
MA
Padovani
Charlotte M
CM
Harsi
M Regina A
MR
Cardoso
Martin D
MD
Chapman
Eurico
E
Arruda
Thomas A E
TA
Platts-Mills
L Karla
LK
Arruda
D000485:Allergens / Q000008:administration & dosage; D001249:Asthma / Q000209:etiology / Q000276:immunology / Q000821:virology; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004802:Eosinophilia / Q000209:etiology; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D012135:Respiratory Sounds / Q000209:etiology* / Q000276:immunology; D012141:Respiratory Tract Infections / Q000209:etiology; D012307:Risk Factors; D014329:Tropical Climate; D014777:Virus Diseases / Q000150:complications; D014780:Viruses / Q000302:isolation & purification
D000485:Allergens; D007073:Immunoglobulin E