House dust mites (Acari : pyroglyphidae) in the cities of Gdansk and Gdynia (Northern Poland)

277 samples of house dust collected in 1996-1998 from 17 flats, three hospi tals, two hotels and one students' hostel situated in the cities of Gdansk and Gdynia were subjected to acarological examination. Acari were found in 50 (37.3%) of 134 samples from the flats, in 11 (15.5%) of 71 samples from the hospitals and in 13 (18.1%) of 72 samples from the hotels. The majority of mites (91.6%) was found in samples that originated from the private fla ts. 95.0% of mites from the flats, 35.0% mites from the hotels and 8.0% mit es from the hospitals belonged to two dust mite species pf the family Pyrog lyphidae: Dermatophagoides pteronyssinus and Dermatophagoides farinae. D. f arinae was significantly predominant and composed 82.8% of the whole pyrogl yphid collection. Samples from private flats contained significantly more m ites than those from hospitals and hotels: mean mites densities per 1 gram of dust were 13.07, 1.03 and 1.00, respectively. The authors suggest that o nly density of house dust mites in private flats may be clinically importan t.