THE USE OF DOMESTIC STEAM CLEANING FOR THE CONTROL OF HOUSE-DUST MITES

Background Control of dust mites using extremes of temperature is an a lternative to the use of acaricides. In the past we have attempted con trol by freezing with liquid nitrogen. The present paper deals with th e opposite extreme, the use of steam. Objective To assess the feasibil ity and effectiveness of a domestic steam cleaner for the control of d ust mites, its effect on mite populations and concentrations of the al lergen Der p 1. Methods A domestic steam cleaner was used to treat car pet squares that had been seeded in the laboratory with known numbers of dust mites (Dermatophagoides pteronyssinus). The number of live mit es was monitored for a period of 4 months in eight treated carpet squa res and eight controls. Dust samples were taken from 12 standardized a reas of carpet in a tenement flat in Glasgow, UK, before and after ste am cleaning treatment, and the concentration of allergen Der p 1 was c ompared with 12 adjacent, control areas. Results No live mites were fo und at any time in the treated carpet squares, whereas in the control squares geometric mean mite population density rose from 11 after 3 da ys to 39 after 1 month, 66 after 2, 122 after 3 and 185 after 4 months . There was a mean reduction of 86.7% in Der p 1 concentration (3.3-0. 44 mu g/g) compared with a reduction of 4.7% (2.22-2.116 mu g/g) in co ntrol areas, a difference that was statistically significant at the 5% level. Conclusion These data indicate that steam cleaning has conside rable potential as an highly effective and efficient method of killing dust mites and reducing concentrations of Der p 1 in domestic premise s.