Baseline levels of the house-dust mite
allergen,
Der p 1, were measured on the carpets and mattresses of 60 pure-mite-sensitive asthmatic children in the Cape Peninsula, by means of an
enzyme-linked
immunosorbent assay (ELISA). High levels of mite
allergens were recorded (range 2-50 micrograms
Der p 1/g dust). In order to investigate the efficacy of the application of
acaricides to carpets and bedding, 3 groups of 20 children were studied. Carpets and mattresses in group A were treated with a
detergent, Metsan (Snowchem), and in group B with Metsan combined with the
acaricide,
Acarosan (Noristan). Group C was a control group in which no treatment was applied. The level of airway hyperreactivity (PC20) to
histamine was measured at the beginning of the study and again 3 months after
acaricide treatment. Significant reductions in carpet
Der p 1 levels were achieved in group A (22.83 v. 13.26 micrograms
Der p 1/g dust; P = 0.04) and group B (21.76 v. 13.26 micrograms
Der p 1/g dust; P = 0.01), but mite levels were not reduced in any of the mattresses treated. There was also no improvement in airway hyperreactivity in any of the groups. This study clearly demonstrates that at present it is not possible to reduce
Der p 1 antigen levels in mattresses in the Cape Peninsula with the available
acaricides, even when one of these is combined with a
detergent solution. Until strategies are developed which will significantly reduce
Der p 1 levels in the bedding of sensitive individuals, a reduction in ongoing airway
inflammation and airway hyperreactivity cannot be expected.