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.


METHODS
Specific IgE against aeroallergens (sIgE) and skin prick test (SPT) reactivity for the most common local allergens were measured in 1128 children aged 4 to 11 years. Data on wheezing and potential confounders were collected by questionnaire. Infections by 8 pathogens were assessed by using serology and stool examination. Associations of wheeze and atopic outcomes with single and multiple infections were analyzed by means of logistic regression.


RESULTS
Negative results for Toxoplasma gondii were associated with a higher prevalence of sIgE (≥0.70 kU/L), whereas negative results for Ascaris lumbricoides, T gondii, herpes simplex virus, and EBV were associated with a higher prevalence of SPT reactivity. Children with 3 or fewer infection markers had a higher prevalence of sIgE and SPT reactivity compared with those with 4 or more infection markers. However, isolated infections or pathogen burden were not associated with the prevalence of atopic or nonatopic wheeze.


CONCLUSIONS
The findings provide support for the idea that the hygiene hypothesis is operating in an urban Latin American context, but its expression is thus far restricted to the atopic status of patients and not the perceived asthma symptoms.
Departamento de Ciências da Biointeração, Instituto de Ciências da Saúde, Universidade Federal da Bahia, Salvador, Bahia, Brazil. neuzalcantara@gmail.com
Neuza Maria
NM
Alcantara-Neves
Rafael Valente
RV
Veiga
Vitor Camilo Cavalcante
VC
Dattoli
Rosimeire Leovigildo
RL
Fiaccone
Renata
R
Esquivel
Álvaro Augusto
ÁA
Cruz
Philip John
PJ
Cooper
Laura Cunha
LC
Rodrigues
Maurício Lima
ML
Barreto
D000485:Allergens / Q000276:immunology; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D061148:Hygiene Hypothesis; D006969:Hypersensitivity, Immediate / Q000453:epidemiology* / Q000276:immunology; D007073:Immunoglobulin E / Q000276:immunology; D007239:Infections / Q000453:epidemiology* / Q000276:immunology; D008297:Male; D012135:Respiratory Sounds; D012882:Skin Tests
D000485:Allergens; D007073:Immunoglobulin E