Allergic asthma to shiitake and oyster mushroom.

. BASIDIOMYCETES spores from edible mushrooms are a very rare cause of respiratory allergies. To our knowledge, we describe here the ®rst case of spores of shiitake and oyster mushroom as a cause of asthma in the same patient. Ever since the age of 15, a 48-year-old truck driver had been suffering from seasonal rhinoconjunctivitis. During the last 3 years he had been complaining of workplace-related attacks of asthma, rhinitis, and conjunctivitis. His work consisted of transporting food, especially mushrooms. The asthmatic attacks occurred immediately after unloading and carrying boxes ®lled with different mushrooms, especially shiitake and oyster mushrooms. The symptoms did not occur when he loaded the boxes from the freezer into the truck, but only when they were thawed. Skin prick tests and speci®c IgE with routine inhalants including molds were negative with the exception of grass and rye pollen. Prick-to-prick tests were strongly positive for shiitake gills (wheal 8 mm) and for oyster mushroom (wheal 7 mm), but negative for the stalk of shiitake as well as for Boletus edulis, Morchella esculenta, Psalliota arvensis, P. bispora, and Cantharellus cibarius. Total serum IgE and ECP levels were elevated to 901 kU/l and 37.7 mg/l, respectively. CAP results for shiitake and oyster mushroom, as well as spores from Japan (shiitake) and (oyster mushroom) Switzerland, were dosedependently positive (Table 1). Spirometry showed a moderately reduced air ow obstruction with a FEV1 of 2170 ml/s (predicted normal 3490 ml/s). Forced vital capacity was 3870 ml (predicted normal 4240 ml). Due to the severe asthma symptoms, the patient refused inhalative provocation tests with mushroom spores. However, the patient's history, the immediate positive skin reactions in the prick-to-prick tests, and the demonstration of a signi®cant amount of IgE to shiitake and oyster extracts supported the allergic, IgE-dependent pathogenesis of this occupational asthma. There are other cases described in the literature in which respiratory symptoms developed in patients involved in the commercial production of shiitake mushrooms. The cause of the respiratory diseases described in 1959 among mushroom workers was considered to be allergy to thermophilic actinomycetes that grew in heated hay. It was described as ``mushroom worker disease'' (1). Later a study of workers at a shiitake farm demonstrated the presence of precipitating IgG antibodies to shiitake spores. Allergic alveolitis developed in these patients within 4±8 months, and three of four examined patients had precipitating antibodies to shiitake spore extract; none of them had IgE (2). In Japan and China, where shiitake is extensively cultivated both outdoors and indoors, up to 9% of the exposed workers in one study developed asthmatic symptoms (3). Oyster mushrooms (Pleurotus ostreatus) are cultivated for human consumption in various subspecies. Their spores are highly potent allergens which can also cause exogenous allergic alveolitis. A reliable ALLERGY 2000: 55 :975^987 . COPYRIGHT G MUNKSGAARD 2000 . ISSN 0105-4538 . ALL RIGHTS RESERVED