Thank you for your recent inquiry.
In answer to your questions:
You have asked about the efficacy of hot water washing:
There is evidence in the literature that heating does denature dust mite allergens and can perhaps make them less immunogenic (see Kikuchi abstract from the Journal of Immunology copied below).
However, this is not the basic rationale for using hot water wash. The major intent for hot water washing is to, by killing dust mites, over time reduce the number of dust mites in the home environment (see the McDonald abstract from the Journal of Allergy and Clinical Immunology copied below).
Thus, it is not that you are physically removing the dust mite.Rather, you are, by killing them each time you use heat, gradually reducing their numbers.
You asked about evidence that allergen covers on the bedding may affect outcomes.
The literature is replete with studies assessing the effect of allergen avoidance on not only the quantity of allergen available, but also the effect of reducing allergen exposure on asthma outcomes and symptoms. When we talk about this, it is important to separate two implications of your question.
One is whether or not complete allergen avoidance is effective, and the second is whether or not the single measure of putting allergen covers on the bedding is effective. There is little doubt that allergen avoidance per se is an effective therapy when allergen is playing a role in the pathogenesis of allergic airway disease (both rhinitis and asthma). Studies many years ago have, at least in my opinion, conclusively demonstrated this effect (see Platts-Mills, et al. and Peroni abstracts copied below).
However, whether single environmental control procedures (e.g., the use of bedding covers) are effective is much more controversial. There are several articles that have looked at this issue not only in terms of dust mite covers, but also commonly employed allergen control measures. There are Cochrane reviews that have evaluated this literature. The interpretation of these published data is, in my opinion, not yet definitive and still open to critique.
For your convenience, I have copied below abstracts taken from a number of the salient articles in the literature that have looked at this issue.
Thus, there is little doubt that environmental control measures (when they adequately reduce allergen exposure) are effective in the treatment of allergic airway disease. However, the issue of single environmental control measures, their effectiveness in reducing allergen exposure and therefore affecting outcomes remains more controversial. The information copied below will allow you to delve further into this issue if you wish.
Thank you again for your inquiry and we hope this response is helpful to you.
The Journal of Immunology www.jimmunol.org
The Journal of Immunology, 2006, 177: 1609-1617.
Yuko Kikuchi*,†, Toshiro Takai2,*, Takatoshi Kuhara*, Mikiko Ota*,§, Takeshi Kato*, Hideki Hatanaka¶, Saori Ichikawa*,||, Tomoko Tokura*, Hisaya Akiba‡, Kouichi Mitsuishi†, Shigaku Ikeda†, Ko Okumura*,‡ and Hideoki Ogawa*,†Crucial Commitment of Proteolytic Activity of a Purified Recombinant Major House Dust Mite Allergen Der p1 to Sensitization toward IgE and IgG Responses1
Atopy (Allergy) Research Center, † Department of Dermatology, and ‡ Department of Immunology, Juntendo University School of Medicine, Tokyo, Japan; § Department of Hygiene Chemistry, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan; Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, Japan; and || Department of Materials and Biological Sciences, Faculty of Science, Japan Women’s University, Tokyo, Japan
The major proteolytic allergen derived from the house dust mite Dermatophagoides pteronyssinus, Der p1, is one of the most clinically relevant allergens worldwide. In the present study, we evaluate the contribution of the proteolytic activity and structure of a highly purified rDer p 1 to immune responses. Mice were i.p. immunized with three forms of rDer p 1 adsorbed to Alum: one enzymatically active, one treated with an irreversible cysteine protease-specific inhibitor, E-64, and one heat denatured. Immunization with E-64-treated or heat-denatured rDer p 1 elicited much less production of serum total IgE and not only rDer p 1-specific IgE but also IgGs compared with immunization with active rDer p 1. Assays for Ab-binding and its inhibition and structural analyses indicated that E-64-treated rDer p 1 retained its global structure and conformational B cell epitopes. A proliferative response and production of IL-5 by spleen cells restimulated with rDer p 1 were observed on immunization with the active rDer p 1 but not E-64-treated rDer p 1. The cells from mice immunized with heat-denatured rDer p 1 exhibited the highest levels of proliferation and production of IL-5 and IFN-γ. The results indicate that the proteolytic activity of the highly purified rDer p 1 crucially commits to the sensitization process, including both IgE and IgG responses. Additionally, we demonstrated immunogenic differences by functional or structural manipulations of the rDer p 1. The findings have implications for sensitization to this relevant allergen in humans and for the design of modified allergen-vaccines for future allergen-specific immunotherapy
Lindy G. McDonald BSc(Hons), Euan Tovey PhD
Journal of Allergy and Clinical Immunology
Volume 90, Issue 4, Part 1, October 1992, Pages 599-608.
The role of water temperature and laundry procedures in reducing house dust mite populations and allergen content of bedding
Purchase
From the Department of Medicine, University of Sydney, New South Wales, Australia
Received 14 October 1991; revised 19 May 1992; Accepted 3 June 1992. Available online 19 April 2005.
Abstract
The effects of various laundry procedures on house dust mites and their allergens have been established. All mites were killed by water temperatures 55 ° C or greater. Killing at lower temperatures was not enhanced by any of the pure detergents or laundry products tested. A cold cycle of laundry washing with or without laundry powder did not remove most live mites from bedding, however, the allergen concentration (Der p I/gm fine dust) was reduced by more than 90%. Dry cleaning did not reduce the allergen concentration of the dust, although most, if not all, mites were killed.
Lancet. 1982 Sep 25;2(8300):675-8.
Reduction of bronchial hyperreactivity during prolonged allergen avoidance.
Platts-Mills TA, Tovey ER, Mitchell EB, Moszoro H, Nock P, Wilkins SR.
Abstract
To study the long-term effects of avoiding domestic allergens, nine asthmatic patients who were allergic to dust mites lived in hospital rooms for two months or more. In all patients symptoms and early morning peak flows improved. In seven patients anti-asthma treatment could be reduced and it was possible to carry out repeated bronchial provocation with histamine. Five of these patients showed a progressive eightfold or greater increase in the concentration of histamine necessary to provoke a 30% fall in forced expiratory volume in one second (PD30). The increase in PD30 in the seven patients during their period of living in hospital was highly significant. Avoidance of important allergens seems not only to result in clinical remissions but in many cases also reduce bronchial hyperreactivity
Am J Respir Crit Care Med. 1994 Jun;149(6):1442-6.
Effective allergen avoidance at high altitude reduces allergen-induced bronchial hyperresponsiveness.
Peroni DG, Boner AL, Vallone G, Antolini I, Warner JO.
Source
Clinica Pediatrica, University of Verona, Italy.
Abstract
We studied the effects of reduced allergen exposure on bronchial hypereactivity (BHR) in two groups of asthmatic children allergic to house dust mites (HDM) living at high altitude for 9 continuous mo. In the first group the serum levels of total and HDM-specific IgE showed significant decreases after 3 mo (p < 0.001 and p < 0.02, respectively) and after 9 mo (p < 0.001). Three months after returning home the total IgE levels had increased significantly (p < 0.001). The mean percentage fall in peak expiratory flow after exercise testing improved after 3 and 9 mo (p < 0.05), but it had deteriorated after 3 mo at home (p < 0.01). The methacholine PD20-FEV1 increased after 3 mo (p = 0.001) and further after 9 mo (p < 0.001), with a decrease after the 3-mo period at sea level (p = 0.01). In the second cohort there was a significant increase in HDM PD20-FEV1 after 6 and 9 mo (p < 0.001), with a slight decrease of magnitude of the allergen-induced late reaction. Histamine PD20-FEV1 significantly increased after 6 and 9 mo at high altitude, particularly in the challenges performed after the HDM bronchial provocation (p < 0.01). Our data demonstrate that allergen avoidance in asthmatic children not only decreases nonspecific BHR but also decreases allergen sensitivity, late allergen-induced bronchial reactions, and enhancement of BHR by allergen challenge.
Hayden ML, Perzanowski M, Matheson L, Scott P, Call RS, Platts-Mills TA.
Ann Allergy Asthma Immunol. 1997 Nov;79(5):437-42.
Dust mite allergen avoidance in the treatment of hospitalized children with asthma.
Source
Department of Medicine, University of Virginia, Charlottesville, USA.
Abstract
Background: Asthma is a leading cause of hospital admission in children. The majority of children with asthma are sensitized and exposed to inhalant allergens that may contribute to chronic airway inflammation.
Objective: To evaluate the practicality and effects of dust mite (D. farinae and D. pteronyssinus) allergen avoidance in homes of children hospitalized with acute asthma.
Methods: Children 5 to 18 years of age who were admitted with asthma to a suburban Atlanta hospital were randomly assigned, without knowledge of allergen sensitization or exposure in their houses, to active (n = 13) or placebo (n = 10) treatment group. Active treatment included encasing mattress, box springs, and pillows in allergen impermeable covers; weekly hot water wash of bed linens; replacement of bedroom carpet with polished flooring; and 3% tannic acid spray to living room carpet. Placebo treatment included permeable encasing for bedding, cold water wash, and water spray for carpet. Dust samples were analyzed for dust mite, cockroach, and cat allergens, while serum samples were analyzed for IgE antibodies to the same allergens. Outcome measures included daily peak expiratory flow rates, spirometry, methacholine inhalation challenge, and hospital readmission.
Results: Children in both groups were similar by demographics, sensitization, and exposure to dust mite allergen. Allergen levels fell > 3-fold in many active and placebo homes. Children in the active group had improved PEFR at 3 and 6 months after intervention (P < .04, P < .05, respectively). Six of seven children in the study who were sensitized and exposed to dust mite allergen demonstrated improved PEFR at 3 months when allergen levels fell in both bedding and bedroom floor. There was no difference in FEV1 or methacholine challenge, although a few children in either group could tolerate methacholine because of bronchial hyperreactivity. Six children (four active and two placebo) were readmitted to hospital during the study.
Conclusion: Increases in PEFR were recorded among children in the active treatment group and also among sensitized patients whose dust mite allergens fell. These results support the hypothesis that avoidance can be effective even among children admitted to hospital. The study was complicated by insufficient numbers of mite-allergic children and poor compliance with diaries and the protocol. Recruitment from the hospital resulted in participants with more severe asthma than anticipated. The results also suggest that many of the patients in this group will continue to have exacerbations triggered by upper or lower respiratory tract infections.
Clin Exp Allergy. 2004 Feb;34(2):268-75.
A review of the effects of impermeable bedding encasements on dust-mite allergen exposure and bronchial hyper-responsiveness in dust-mite-sensitized patients.
Recer GM.
Source
New York State Department of Health, Center for Environmental Health, Troy, NY 12180, USA.
Abstract
Background: Sensitization and exposure to dust-mite antigens are causative factors in the development and exacerbation of asthma. Impermeable bedding encasements are considered a first-line treatment to reduce dust-mite antigen exposure in clinical asthma-management guidelines. Public-health recommendations for environmental asthma treatments should be based on the weight of evidence supporting the reliability of environmental interventions so that uncertainties regarding their effectiveness can be accurately communicated to patients, and so that limited public-health resources can be most effectively utilized.
Objective: To evaluate the strength of a clinical-trial evidence supporting the efficacy of bedding encasements as an asthma treatment.
Methods: A narrative review was conducted of all clinical trials involving bedding encasement for the treatment of asthma. Collective statistical analyses were also performed to characterize the quantitative effect of bedding encasement on dust-mite allergen exposure and bronchial hyper-responsiveness (BHR) when used by asthma patients.
Results: Over 30 clinical trials were reviewed. Of those studies reporting adequate exposure and BHR results, four reported significant reduction in dust-mite allergen exposure and concomitant BHR reduction in active-treatment groups using bedding encasements. In 10 studies, mite-allergen exposure was reportedly decreased during the study, but BHR was not changed in the active-treatment group or was reduced to a similar degree in the active-treatment and control groups. Five other studies reported a lack of significant effect of the intervention on exposure and BHR. Collective paired analyses found that the effect of bedding encasement on allergen exposure and BHR tended toward only a modest, non-significant improvement. Collectively, effects of bedding encasement on BHR and dust-mite allergen exposure were modestly correlated only when the baseline exposure was above 2 microg Type 1 antigen per gram settled dust.
Conclusion: Although bedding encasement might be an effective asthma treatment under some conditions, when implemented in clinical trials by asthma patients, its effectiveness is inconsistent and appears to be, at best, modest. Therefore, its significance as a reliable asthma management modality for any individual asthma patient is uncertain. Where resource constraints are significant, targeting the use of variably effective interventions such as bedding encasements toward those patient sub-populations most likely to derive substantial benefit may gain the largest net public-health benefit.
Cochrane Database Syst Rev. 2010 Jul 7;(7):CD001563.
House dust mite avoidance measures for perennial allergic rhinitis.
Sheikh A, Hurwitz B, Nurmatov U, van Schayck CP.
Source
Centre for Population Health Sciences, The University of Edinburgh, Medical School, Doorway 3, Teviot Place, Edinburgh, UK, EH8 9AG.
Abstract
Background: This is an update of a Cochrane Review first published in The Cochrane Library in Issue 4, 2001 and previously updated in 2003 and 2007.It is estimated that in developed countries approximately 30% of the general population suffer from one or more allergic disorders, of which allergic rhinitis is particularly common. Perennial rhinitis is most often due to allergy to the house dust mite. In such patients house dust mite avoidance is logical, but there is considerable uncertainty regarding the efficacy and effectiveness of interventions designed to reduce dust mite exposure.
Objectives: To assess the benefit (and harm) of measures designed to reduce house dust mite exposure in the management of house dust mite sensitive allergic rhinitis.
Search Strategy: Our search included the Cochrane Ear, Nose and Throat Disorders Group Trials Register, the Cochrane Central Register of Controlled Trials Register (CENTRAL) (The Cochrane Library Issue 4, 2009), MEDLINE and EMBASE. The date of the last search was 31 December 2009.
Selection Criteria: Randomised controlled trials, with or without blinding, in which house dust mite control measures have been evaluated in comparison with placebo or other dust mite avoidance measures, in patients with clinician-diagnosed allergic rhinitis and confirmed allergy to dust mite.
Data Collections and Analysis: Two authors independently screened titles and abstracts, graded methodological quality using the Cochrane approach and extracted data. Meta-analysis was neither possible nor appropriate due to heterogeneity of the patient groups studied.
Main Results: Nine trials involving 501 participants satisfied the inclusion criteria. Only two studies investigating the effectiveness of mite impermeable bedding covers were of good quality; the remaining seven studies were small and of poor quality. Two trials investigated the efficacy of acaricides, another two trials investigated the role of high-efficiency particulate air (HEPA) filters. One trial, using a factorial design, investigated the efficacy of both acaricide and house dust mite impermeable bedding covers in isolation and combination; the remaining four trials investigated the efficacy of bedroom environmental control programmes involving use of house dust mite impermeable bedding covers. Seven of the nine trials reported that, when compared with control, the interventions studied resulted in significant reductions in house dust mite load. Of the interventions studied to date, acaricides appear to be the most promising type of intervention, although the findings from these studies need to be interpreted with care because of their methodological limitations. House dust mite impermeable bedding as an isolated intervention is unlikely to offer clinical benefit. No serious adverse effects were reported from any of the interventions.
Authors’ Conclusions: Trials to date have on the whole been small and of poor methodological quality, making it difficult to offer any definitive recommendations on the role, if any, of house dust mite avoidance measures in the management of house dust mite sensitive perennial allergic rhinitis. The results of these studies suggest that use of acaricides and extensive bedroom-based environmental control programmes may be of some benefit in reducing rhinitis symptoms and, if considered appropriate, these should be the interventions of choice. Isolated use of house dust mite impermeable bedding is unlikely to prove effective
Engl J Med. 2003 Jul 17;349(3):237-46.
Evaluation of impermeable covers for bedding in patients with allergic rhinitis.
Terreehorst I, Hak E, Oosting AJ, Tempels-Pavlica Z, de Monchy JG, Bruijnzeel-Koomen CA, Aalberse RC, Gerth van Wijk R.
Source
Department of Allergology, Erasmus Medical Center, Rotterdam, Netherlands.
Abstract
Background: Encasing bedding in impermeable covers reduces exposure to house-dust mites, but the clinical benefit of this intervention as part of mite-avoidance measures for patients with allergic rhinitis is not known. We performed a multicenter, randomized, placebo-controlled trial of one year of use of impermeable bedding covers in the bedrooms of patients with rhinitis who were sensitized to house-dust mites to determine the effects on the signs and symptoms of disease.
Methods: Three participating university medical centers enrolled 279 patients with allergic rhinitis who were randomly assigned to receive impermeable or non-impermeable (control) covers for their mattress, pillow, and duvet or blanket. At the start of the study, all participants received information on general allergen-avoidance measures. The severity of rhinitis was measured on a rhinitis-specific visual-analogue scale and by means of a daily symptom score and nasal allergen provocation testing. We also measured the concentrations of Dermatophagoides pteronyssinus (Der p1) and D. farinae (Der f1) in dust from patients' mattresses, bedroom floors, and living-room floors at base line and after 12 months as a measure of the efficacy of the intervention.
Results: A total of 232 patients completed the study. There was a significant reduction in Der p1 and Der f1 concentrations in the mattresses of the impermeable-cover group, whereas there was no significant reduction in the control group. However, there was no significant effect on the clinical outcome measures. Analyses of subgroups defined according to age, level of exposure, type and severity of sensitization, or characteristics of the patient's home had similar results.
Conclusions: Mite-proof bedding covers, as part of a structured allergy-control program, reduced the level of exposure to mite allergens. Despite the success of the intervention, this single avoidance measure did not lead to a significant improvement of clinical symptoms in patients with allergic rhinitis.
Sincerely,
Phil Lieberman, M.D.