Contact angioedema and conjunctivitis caused by Lumbricus terrestris: cross‐reactivity with Anisakis simplex

Abstract

The common earthworm (Lumbricus terrestris) is classified in the phylum Annelida, class Oligochaeta. Despite the fact that it is frequently used as a fishing bait, hypersensitivity reactions have exceptionally been described. Many allergic reactions to other species included in the phylum Annelida have been communicated, and so have happened with other kind of fishing baits, such as insect larvae or maggots. But isolated skin reactions are infrequent. A 51-year-old amateur fisherman, previously diagnosed of contact dermatitis to niquel and subclinic allergy to Anisakis simplex, suffered from several episodes during 2 months of intense facial edema and conjunctival hyperemia and pruritus immediately after rubbing his eyes while handling earthworms. He did not develop respiratory symptoms. He required emergency medical attention, and the symptoms resolved after 24 h with corticosteroids and antihistaminics. He had been using common earthworms (Lumbricus terrestris) weekly for more than 20 years as fishing baits with good tolerance. Allergologic study. Skin prick tests with common pneumoallergens were negative, and positive to A. simplex (wheal diameter: 5 mm). A prick-prick test with L. terrestris produced a 40-mm diameter wheal with pseudopodes (Fig. 1). Two atopic and two nonatopic control subjects tested negative. Total immunoglobulin (Ig)E measured 344 kU/l, and specific IgE to A. simplex was 6.50 kU/l (Pharmacia CAP System). Lumbricus terrestris proteins were extracted in phosphate-buffered saline (protein concentration: 6.4 mg/ml). A peroxidase-linked immunosorbent assay was performed, detecting specific IgE antibodies to L. terrestris in the patient’s sera. The L. terrestris and A. simplex extracts were run in a 12% sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) according to the discontinuous method described by Laemmli and co-workers (1). Coomassie Brilliant Blue dying revealed six protein bands ranging from 100 to 20 kDa. These proteins were electrophoretically transferred to polyvinylidene fluoride (PVDF) membranes, according to the method of Towbin et al. (2). Later, the membranes were incubated with serum from the patient and two controls, and next with peroxidase-linked antihuman IgE antibodies. Two allergenic bands were shown of >100 and 20 kDa in L. terrestris and an IgE reacting band of 46 kDa was detected in A. simplex. Further, we performed an immunoblot IgE inhibition assay using a commercial extract of A. simplex. The 20 kDa L. terrestris allergen was totally inhibited by A. simplex. Despite our recommendations, the patient kept on using L. terrestris as fishing baits. He avoided direct contact with the nematodes by wearing latex gloves which, so far, have prevented from the development of symptoms. Discussion. We report a case of contact angioedema and conjunctivitis caused by allergy to a common earthworm L. terrestris. A type I hypersensitivity mechanism has been demonstrated by in vivo and in vitro studies. Many different species are used as natural fishing baits, including crustaceans, insect larvae, maggots, and worms. Although sensitization to fishing baits is not a common AL LERGY 2 0 0 7 : 6 2 : 8 4 – 9 3 • a 2007 THE AUTHORS • JOURNAL COMPILAT ION a 2007 BLACKWELL MUNKSGAARD • CONTRIBUT IONS TO THIS SECT ION WILL NOT UNDERGO PEER REV IEW, BUT WILL BE REV IEWED BY THE ASSOCIATE EDITORS •