Common environmental allergens stimulate IgE responses and produce allergic disease, but the allergens that produce the most potent IgE responses in nature originate from helminthic parasites.1 ,2 Since parasitic infection is endemic in the majority of the world’s population, the relationship between helminthic infection and the IgE response is highly relevant to the understanding of allergic diseases. There is a general consensus that IgE antibody is an important component of the immune resistance to helminthiasis,5-9 although some conflicting results have been obtained.3 ,4 Local IgE reactions can create unfavourable conditions in the gut for intestinal parasites, and IgE can mediate the cytotoxic activity of eosinophils against parasitic larvae. These observations have led to the concept that, from an evolutionary perspective, the primary function of the allergic response may be as part of an anti-parasitic protective mechanism, and allergic disease may be the undesirable reaction towards otherwise inoffensive environmental substances.10 In developed countries the prevalence of allergic disease has increased over recent years at the same time that …