Three patients with hypersensitivity pneumonitis caused by inhalation of spores of Cortinus shiitake (Lentinus edodes) cultivated in vinyl houses were observed. These three patients developed the disease after harvesting shiitake for several hours in closed frame houses with a heater in the autum and winter. The frames were full of spores of shiitake and the patients suffered from a discordant feeling, systemic weakness, a feeling of cold, fever (over 38 C), a feeling of airway occlusion, a slight cough and sputum. These symptoms disappeared during rest the next day.
Case 1 was examined by the inhalation provocation test with a suspension of shiitake spores and spore-allergen. This test caused several clinical symptoms (fever, airway occlusion and various symptomatic feelings), leucocytosis, decrease of PaO₂ a positive reaction of CRP and X-ray findings (appearance of interstitial pneumonitis shadows).
The 3 patients were considered to be suffering from allergic hypersensitivity pneumonitis due to inhalation of spores of Cortinus shiitake, because of their work, the development of symptoms after work in specific occupational conditions, a positive reaction to precipitating antibody against spore-allergen of shiitake, negative reactions to precipitation antibodies to 11 molds-allergens, various abnormal values in immunological tests and a positive reaction in a provocation test in one case.
In a survey of 45 shiitake-grower, it was found that 6 (13.3%) suffered from respiratory disease. No difference was found in the incidence of intracutaneous reactions to spore-allergen or allergen of dried shiitake in non-farm workers. Among 31 growers of shiitake a precipitation antibody to spore-allergen was observed only in these three patients. These results indicate that an allergic disposition is very important for development of hypersensitivity pneumonitis.