Partial mattress encasing significantly reduces house dust mite antigen onbed sheet surface: a controlled trial

Background: The most effective measure in house dust mite antigen reduction is mattress encasing with an impermeable membrane. A reduction in encasing costs will help increase patients' compliance in mite antigen avoidance. Objective: To investigate the effectiveness of partial mattress encasing wi th a nylon sheet produced in Thailand on the reduction of group I mite anti gens from beddings. Methods: Sixty regularly-used beds from the house officers' dormitory of th e Siriraj Hospital Mahidol University, Thailand, were randomly matched into two groups according to mite antigen levels. The control group (CG) used o nly regular cotton bed sheets whereas the partial encasing group (PG) used mattresses partially covered with a locally produced nylon sheet underneath the regular cotton bed sheets. Dust collection from the beddings was perfo rmed at baseline, 2, 4 and 6 months after application of the nylon sheet. M ite antigen levels were detected by a two step monoclonal antibody ELISA. Results: Mite antigen levels in both groups were not different at the begin ning of the study. The PG had significantly lower group I antigen levels on regular bed sheet surfaces than the CG (P < .004) at the 2, 4 and 6 month timepoints. However, antigen levels on the mattress surface of the PG was s ignificantly higher than the CG at the end of the study (P < .004). The bar rier efficacy of the nylon sheet in preventing migration of group I mite an tigens from the mattress to the surface of the regular cotton bed sheet was 94% whereas that of the regular cotton bed sheet was 66% (P = .007). Conclusion: Partial mattress encasing with a locally made nylon sheet can r educe mite antigens on the regular cotton bed sheet surfaces for up to 6 mo nths.