Effectiveness of house dust mite control measures in babies' beds: a randomised controlled trial

Introduction: Sensitisation to house dust mites is the strongest risk factor for asthma in coastal Australia. Common reservoirs are pillows, mattresses and bedding. We are conducting a study to test the efficacy of reducing exposure to house dust mites. Methods: Children at high risk of developing asthma were recruited antenatally and randomised into control and active groups. Both groups were advised on simple cleaning routines. The active intervention group was asked to wash the child's bedding in Acaril, an acaracidal detergent, before birth and at three month intervals. Allergen impermeable coverings were given to encase the child's cot mattress. Dust was collected at 4 weeks, 3 months and 6 months after birth and assayed for Der p1. Results: The table shows the geometric means of Der p1 (μg/g dust) and the 95% confidence intervals. Allergen levels at 4 weeks were low in both groups. In the active group, levels remained low compared to those in the control group, which gradually increased. Control group Active group p value n Mean (95% CI) n Mean (95% CI) 4 weeks 106 3.9(2.7,5.5) 99 2.8(2.1,3.7) 0.161 3 months 74 6.1 (4.3,8.7) 78 2.7 (2.0,3.7) 0.001 6 months 37 10.9(6.9,17.0) 38 3.2(2.1,4.8) <0.0001 Conclusion: Washing in Acaril, and using allergen impermeable covers results in a significant reduction of house dust mite allergen levels in babies' beds. These interventions may help to prevent the onset of asthma and allergy.