Three cases of hypersensitivity pneumonitis caused by inhalation of spores of Pholiota nameko and the background of the disease

: Here we report a new type of hypersensitivity pneumonitis caused by inhalation of spores of Pholiota nameko. P. nameko is a kind of mushroom which is of Japanese delicacy. Among people who are working in nameko cultivation, we found three patients suffering from hypersensitivity pneumonitis, and identified that it was caused by inhalation of spores of P. nameko. Every patient was engaged in indoor nameko cultivation inside a building equipped with a air and moisture conditioning system for two to ten years. In the indoor environment, it was thought that they were exposed to and inhaled a high density of nameko spores. Among 15 healthy indoor nameko growers, we found 6 who had precipitating antibody against extracts from nameko spores; however, there were no antibody positive people in 17 outdoor nameko growers. As seen in dairy farmers, it was clarified that there is a percentage of precipitin positive nameko growers who are asymptomatic. This is concrete evidence that changes of mushroom cultivation style can induce a new type of hypersensitivity pneumonitis. These findings were considered to be an important experience from the view points of environmental pulmonary diseases and industrial medicine.