Fifty mattress dust samples from private houses were examined—all were mite infested. Dermatophagoides pteronyssinus occurred in all samples and accounted for 81% of all mites.
In thirty-two paired samples the total mite population of bedroom floor dust was only 10% of that found in the corresponding mattress dust. D. pteronyssinus was the dominant species in both and the population of this mite amounted to 7.5% of that found in the mattress dust.
An analysis of mattress dust from 100 hospital beds showed that ninety-four mattresses were mite free; the other six contained only seven mites, all D. pteronyssinus.
It is suggested that frequent changing and washing of bed linen and brushing and cleaning of mattresses were the main factors in preventing mite infestation in the Cardiff hospitals.