Inverse association between skin response to aeroallergens and Schistosomamansoni infection

Background: Helminthic infections and allergic disease are highly prevalent in many areas of the world. It is known that IgE antibodies are involved i n the pathogenesis of both helminthiasis and atopy. However, the consequenc es of the presence of helminthic infections in atopic patients are still no t completely understood. Methods: Subjects infected by Schistosoma mansoni with more than 200 eggs/g of feces (n = 42) and uninfected subjects (n = 13 3) were selected from an endemic area of schistosomiasis. The history of al lergy and results of the immediate hypersensitivity prick tests with inhala nt allergen extracts were registered. Total IgE and IgE specific to S. mans oni and aeroallergens were measured in serum by ELISA. Results: The proport ion of individuals with a positive skin test to allergens was higher in the uninfected group (24.3%) than in the group with more than 200 eggs/g of fe ces (4.8%). The odds of atopy (defined as a positive test for at least one of the antigens) were 5 times higher (odds ratio = 7.0; 95% confidence inte rval = 1.6-31.1%; p = 0.01) in the un infected group, after taking into acc ount the potential influence of gender and age. While there was a tendency for higher total and S. mansoni-specific IgE levels in infected patients, a n opposite trend, that is higher aeroallergen-specific IgE, was observed in uninfected subjects. Conclusions: There was a strong and statistically sig nificant inverse association between the immediate skin test response to co mmon aeroallergens and infection by S. mansoni. The results indicate that i mmediate hypersensitivity reactions may be suppressed in S. mansoni-infecte d individuals. Copyright (C) 2000 S. Karger AG,Basel.