Sensitization to Ascaris lumbricoides and severity of childhood asthma in Costa Rica.

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 FEV(1) and FEV(1)/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.