Anaphylactic reaction elicited by condurango bark in a patient allergic to natural rubber latex

Abstract

Since the 1980s, immediate-type allergy to natural rubber latex (NRL), frequently used in surgical gloves and other medical devices but also found in a variety of common products that have become part of our everyday environment, has become a serious health problem.1 In particular, health care workers, other persons professionally exposed to NRL, and patients with multiple medical interventions are affected. In many patients with NRL allergy, hypersensitivity to certain food items has been reported.2 We here report on a patient allergic to NRL who experienced anaphylactic reactions elicited by a herbal tea. A 25-year-old male nurse had generalized urticaria, angioedema, and asthma 30 minutes after he had ingested a herbal tea. He gave a history of seasonal respiratory symptoms caused by pollens. Furthermore, he was known to be allergic to NRL, with exposure causing rhinoconjunctivitis and asthma. The herbal tea contained blackberry leaves, caraway, fennel, camomile, orange peel, and condurango bark. At the time of skin prick testing, immediate type reactions were found to various aeroallergens (including birch, grass, and mugwort pollens), various food allergens, NRL milk, the herbal tea, and condurango bark. Neither the reaction to the herbal tea nor to the condurango bark were found in 10 control subjects, and the patient did not react to the other constituents of the tea. In the patient’s serum specific IgE antibodies were demonstrable by CAP-FEIA (Pharmacia, Freiburg, Germany) to a variety of aeroallergens, a variety of food allergens, NRL (17.2 kU/L), and condurango bark (9.79 kU/L). Oral challenge tests with incremental doses of the herbal tea (20 mg/ml water; ranging up to 100 ml) and condurango bark (3 mg/ml water; ranging up to 100 ml) resulted in both generalized urticaria and asthma starting 30 minutes after the last dose; symptoms cleared quickly with adequate treatment. To verify the relationship between hypersensitivity to condurango bark and NRL allergy, inhibition tests were performed. Binding of specific IgE antibodies to NRL in vitro was inhibited up to 57% after preincubation with condurango bark and up to 62% after preincubation with NRL (Fig. 1). Correspondingly, after preincubation with different concentrations (ranging from 0.032 to 32 mg/ml) of NRL (skin prick test solution; ALK Horsholm, Denmark) the binding of the patient’s IgE antibodies to condurango bark was inhibited up to 85%. Control tests showed that binding of the patient’s specific IgE to grass, birch, or mugwort pollen was inhibited by at most 20% by condurango bark, whereas inhibition after preincubation with the respective allergens ranged from 80% to 100%. Marsdenia condurango (family Asclepiadaceae) is a shrub growing in Colombia, Ecuador, Peru, some other parts of South America, and East Africa.3 Condurango bark, also known as eagle-vine bark, contains numerous substances and has been used for centuries as a folk medicine remedy to treat stomachache, syphilis, or snake bite. Currently it is used in some preparations for supplementary treatment of gastritis or stomach ulcer. It also can be present in herb-flavored liqueurs or bitter drinks. At higher doses, typical side effects of condurango bark are convulsions and paralysis. To our knowledge this is the first report of IgE-mediated hypersensitivity reaction caused by condurango bark.