Mechanisms of asthma and allergic inflammation
Sensitization to Ascaris lumbricoides and severity of childhood asthma in Costa Rica

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Background

Little is known about sensitization (defined as a positive IgE) to helminths and disease severity in patients with asthma.

Objectives

To examine the relationship between sensitization (defined as a positive IgE) to Ascaris lumbricoides and measures of asthma morbidity and severity in a Costa Rican population with low prevalence of parasitic infection but high prevalence of parasitic exposure.

Methods

Cross-sectional study of 439 children (ages 6 to 14 years) with asthma. Linear regression and logistic regression were used for the multivariate statistical analysis.

Results

After adjustment for parental education and other covariates, sensitization to Ascaris lumbricoides was associated with having at least 1 positive skin test to allergens (odds ratio, 5.15; 95% CI, 2.36-11.21; P < .001), increased total serum IgE and eosinophils in peripheral blood, reductions in FEV1 and FEV1/forced vital capacity, increased airway responsiveness and bronchodilator responsiveness, and hospitalizations for asthma in the previous year (odds ratio, 3.08; 95% CI, 1.23-7.68; P = .02).

Conclusion

Sensitization to Ascaris lumbricoides is associated with increased severity and morbidity of asthma among children in Costa Rica. This association is likely mediated by an increased degree of atopy among children with asthma who are sensitized to Ascaris.

Clinical implications

In areas with a low prevalence of helminthiasis such as Costa Rica, Ascaris sensitization may be an important marker of severe atopy and disease morbidity in children with asthma.

Section snippets

Study population

Children who participated in this study were index cases for a genetic study of nuclear families of children with asthma in Costa Rica. From February 2001 to March 2005, short questionnaires were sent to the parents of 9054 children age 6 to 14 years who were enrolled in 95 schools in Costa Rica. Of the questionnaires distributed, 5355 (59.1%) were returned. Children were eligible for inclusion in the study if they had asthma (defined as physician-diagnosed asthma and at least 2 respiratory

Results

A comparison of selected characteristics of children who were (n = 171) and were not (n = 268) sensitized to Ascaris is presented in Tables I (for categorical variables) and II (for continuous variables). Children who were sensitized to Ascaris were more likely to be boys, to have been hospitalized for asthma in the previous year, and to have at least 1 positive skin test to allergens, a positive IgE to dust mite or cockroach, markedly increased airway responsiveness to methacholine (a 20% fall

Discussion

To our knowledge, this is the first report of an association between sensitization to A lumbricoides and increased asthma morbidity. Among children with asthma in Costa Rica, sensitization to Ascaris was associated with increased odds of allergic sensitization, increased levels of total serum IgE and eosinophils in peripheral blood, increased airway responsiveness and bronchodilator responsiveness, reduced lung function, and hospitalizations for asthma in the previous year.

Studies of children

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  • Cited by (0)

    Supported by grants HL04370 and HL66289 from the National Institutes of Health.

    Disclosure of potential conflict of interest: E. K. Silverman has consulting arrangements with GlaxoSmithKline, has received grant support from GlaxoSmithKline, has received honoraria from Bayer, and received money from Wyeth for a talk on chronic obstructive pulmonary disease genetics. The rest of the authors have declared that they have no conflict of interest.

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