Incidence of Demodex folliculorum on skin of lids and nose.

The incidence of follicle mites (Demodex) has been studied in 206 non-selected subjects by means of adhesive tape impressions on skin during daytime of nose and lids and moist storage of the tape. The incidence was seen to rise with increasing age: 4% in young subjects, 30% in the age group of 20 to 80, and 47% in older. The mite was more often present on the skin of the nose (17%) than on that of the upper lid (8%), while the incidence on the lower lid was between these 2 extremes (13%). A total of 126 Demodex mites were detected (123 Demodex folliculorum and 3 Demodex brevis), all full-grown. Of these, 41% were ghosts. The migration was evenly distributed in all directions within the areas examined. About 0.2% of the mites can be roughly estimated to have migrated at a certain point of time from the follicles of the nose to its skin.