Distribution and density of house dust mites Dermatophagoides spp. (Acarina:Pyroglypidae) in the mattresses of two areas of Rome, Italy.

The distribution of Dermatophagoides farinae and D. pteronyssinus in two groups of houses in Rome was investigated by means of weekly sampling of dust on mattresses during the period of high mite density (May-July, 1994). All mattresses were infested; overall 4,179 live and dead mites were collected. In the two examined areas, a difference in species distribution was observed. D farinae was always the prevalent species, it was 94.7% in area A and 64.1% in area B; only in houses 9 and 10 D. pteronyssinus was the most abundant species (71.4% and 45.8%). Housekeeping practices were investigated by interviewing the tenants and relative humidily and indoor/outdoor temperature were measured during each weekly sampling. A correlation analysis revealed a significant relationship between housekeeping practices and mite density (r = 0.83). The poorest housekeeping practices produced the heaviest mite infestation, while good ones were associated with low densities.