Ascaris lumbricoides and allergic asthma: A new perspective.
Infestation of humans with the parasite Ascaris lumbricoides may induce high total serum IgE levels, but the influence of this immunogenic response on allergic asthma has not been defined. In this study, the specific antiparasitic IgE-mediated response as determined by skin-prick testing was related to the incidence of allergic asthma in Ascaris-infested patients. A limited number--17% of the non-allergic controls and 51% of the allergic asthmatics--had a clinically detectable immunogenic response to the parasite. The predicted incidence of asthma was significantly higher than the observed incidence in the subjects in whom the Ascaris skin test was positive. This was not found in subjects in whom the Ascaris skin test was negative. Inhalation of Ascaris antigen induced asthmatic reactions in 7 of 8 patients who were Ascaris-positive on skin testing, but not in the negative controls. The groups of patients who respond immunogenically to parasite infestation need to be defined, as they may be predisposed to allergic diseases such as asthma.