title: The Melbourne House Dust Mite Study: long-term efficacy of house dust mite reduction strategies.
abstract: BACKGROUND
  Asthma severity among mite-sensitized individuals appears to be related to the degree of mite allergen exposure.
  
  
  OBJECTIVE
  The objective of this study was to assess the long-term effectiveness of mite avoidance measures in the homes of asthmatic children in Melbourne, Australia.
  
  
  METHODS
  The concentration of house dust mite allergen (Der p 1) was measured on the child's mattress surfaces and bedroom floors in 85 homes on 10 occasions over a 16-month period. After the first three visits, all mattresses were covered with a semipermeable encasement, and carpeted bedroom floors were randomly allocated to regular applications of a placebo or an "anti-mite" shampoo.
  
  
  RESULTS
  The concentration of Der p 1 recovered was initially high in the carpeted bedrooms (n = 66) (41.1, 95% confidence interval, 30.7 to 55.0 microg Der p 1 per gm) and mattresses (n = 85) (39.6, 27.2 to 57.7). During the initial observation period the concentration of mite allergen fell in the treatment, placebo, and parental control groups. During the seven treatment periods, no differences were seen between the Der p 1 concentrations in the groups using the "anti-mite" shampoo, placebo shampoo, or the parental control group (e.g., at visit 4; 12.6, 8.2 to 19.5; 14.8, 8.6 to 25.1; and 12.0, 8.1 to 17.7 microg/gm, respectively). In contrast, the concentration of Der p 1 in samples from uncarpeted floors and mattress encasements was low (4.1, 2.1 to 8.0 microg/gm and 4.2, 2.6 to 6.5 microg/gm, respectively) and insufficient dust for analysis was frequently obtained from these sites.
  
  
  CONCLUSIONS
  There was no additional benefit from the use of an "anti-mite" shampoo. The absence of carpets and the use of mattress encasements was a useful long-term strategy for mite allergen avoidance.
authors.affiliation: Department of Allergy, Royal Children's Hospital, Melbourne, Victoria, Australia.
authors.forename: R
authors.initials: R
authors.lastname: Sporik
authors.forename: D J
authors.initials: DJ
authors.lastname: Hill
authors.forename: P J
authors.initials: PJ
authors.lastname: Thompson
authors.forename: G A
authors.initials: GA
authors.lastname: Stewart
authors.forename: J B
authors.initials: JB
authors.lastname: Carlin
authors.forename: T M
authors.initials: TM
authors.lastname: Nolan
authors.forename: A S
authors.initials: AS
authors.lastname: Kemp
authors.forename: C S
authors.initials: CS
authors.lastname: Hosking
mesh_terms: D000818:Animals; D039741:Antigens, Dermatophagoides; D001249:Asthma / Q000628:therapy*; D002648:Child; D004391:Dust / Q000009:adverse effects*; D006023:Glycoproteins / Q000032:analysis*; D006801:Humans; D008925:Mites / Q000276:immunology*; D012621:Seasons
chemical_list: D039741:Antigens, Dermatophagoides; D004391:Dust; D006023:Glycoproteins