Abstract
We bred 20 adults of female Dermatophagoides farinae with 5 g of house-dust samples, and measured periodically the mite density and the amount of mite allergen. In most of the house-dust samples, the mite density increased exponentially, followed by a rapid increase of the allergen, especially Der fl which was originated from mite feces. In a house-dust sample which was rich in nutrients for mites, the number of mites increased more than 2,000 times that of the initial density (4 mites per gram of fine dust) after 15-week breeding, and the Der fl reached over 780,000 ng per gram of fine dust after 20-week breeding. This increase of the mite density was greater than that reported on other nutritious culture media, such as mixtures of dried yeast, powdered fish, etc. Another house-dust sample collected from a vacant house gave a very little increase of the number of mites and the allergen, showing low nutritive value. By adding human dander/skin scales to this sample, good propagation of the mites and a rapid increase of the allergen could be obtained. It was concluded that house-dust and human dander/skin scales were nutritious enough for mites to produce a large amount of mite allergen.
