Eradication of house dust mite from homes of atopic asthmatic subjects: A double-blind trial (original) (raw)
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Effect of improved home ventilation on asthma control and house dust mite allergen levels
Allergy, 2009
Background: The warm, humid environment in modern homes favours the dust mite population, but the effect of improved home ventilation on asthma control has not been established. We tested the hypothesis that a domestic mechanical heat recovery ventilation system (MHRV), in addition to allergen avoidance measures, can improve asthma control by attenuating re-colonization rates.Methods: We conducted a randomized double-blind placebo-controlled parallel group trial of the installation of MHRV activated in half the homes of 120 adults with asthma, allergic to Dermatophagoides pteronyssinus. All homes had carpets steam cleaned and new bedding and mattress covers at baseline. The primary outcome was morning peak expiratory flow (PEF) at 12 months.Results: At 12 months, the primary end-point; change in mean morning PEF as compared with baseline, did not differ between the MHRV group and the control group (mean difference 13.5 l/min, 95% CI: −2.6 to 29.8, P = 0.10). However, a secondary end-point; evening mean PEF, was significantly improved in the MHRV group (mean difference 24.5 l/min, 95% CI: 8.9–40.1, P = 0.002). Indoor relative humidity was reduced in MHRV homes, but there was no difference between the groups in Der p 1 levels, compared with baseline.Conclusions: The addition of MHRV to house dust mite eradication strategies did not achieve a reduction in mite allergen levels, but did improve evening PEF.
Journal of Allergy and Clinical Immunology, 2000
Background: The relationship between exposure to house dust mite (HDM) allergens and prevalence of sensitization to these allergens in patients with asthma has been confirmed in many studies. Mite population growth is regulated by humidity. Reducing humidity and removing allergen by efficient vacuuming should control mite allergen and reduce symptoms. Objective: We sought to investigate the effect of mechanical ventilation and high-efficiency vacuuming on HDM numbers and Der p 1 concentrations in the homes of mite-sensitive asthmatic subjects and to evaluate the effect of any reductions on symptoms.
Exposure to house dust mite allergens and the clinical activity of asthma
Journal of Allergy and Clinical Immunology, 1996
Background: House dust mite allergens play an important role in inducing IgE-mediated sensitization and the development of bronchial hyperresponsiveness (BHR) and asthma. This study investigated the relationship between mite allergen exposure and the clinical activity and severity of asthma. Methods: Nonsmoking adult patients with asthma (n = 53) were randomly recruited from the asthma registry of two large family practitioner surgeries. Each participant underwent skin testing with common inhalant allergens, a methacholine bronchoprovocation test, and pulmonary function testing on up to 3 separate occasions over a 4-week period. BHR was expressed both as PDeo and dose-response ratio (DRR), and the patients with PD2o of less than 12.25/xmol methacholine were classified as methacholine reactors. Patients were also asked to record peak expiratory flow rate (PEFR) values at 2-hour intervals during waking hours for 1 month. Daily PEFR variability was calculated as amplitude percent mean. Dust samples were collected by vacuuming bedding, bedroom carpets and mattresses. In addition, in the homes of 32 subjects with positive skin test responses to mites, airborne samples were taken overnight for 8 hours with a personal sampler attached to each subject's pillow. Der p 1 and Der p 2 levels were determined by a two-site monoclonal antibody-based ELISA. Results: No difference in mite allergen exposure was found between subjects who were sensitive to mites and those who were not. However, mite-sensitive methacholine reactors were exposed to significantly higher concentrations of Der p 1 in beds than mite-sensitive methacholine nonreactors (13.2/xg/gm and 1.45/xg/gm, respectively," p < 0.02). Der p 1 and Der p 2 were undetectable in 30 of 32 airborne samples. In mite-sensitive patients both Der p 1 and Der p 2 in beds significantly correlated with BHR (PDeo: r = -0.49, DRR, r = 0.49; PD2o: r = -0.46, DRR: r = 0.43) and amplitudepercent mean PEFR (r = 0.38, r = 0.41)for Derp 1 and Derp 2, respectively. There was a significant negative correlation between exposure to Der p I and percent predicted FEV 1 (r = -0.43). The correlation between Der p 2 and percent predicted FEV z just failed to reach a significant level but showed a clear trend (r = -0.35, p = 0.068). Conclusions: Clinical activity and severity of asthma (measured by the level of BHR, PEFR variability, and percent predicted FEV1) in mite-sensitive patients is related to exposure to mite allergens in the dust reservoir, with levels in bed being an important indicator that correlated with disease activity. (J Allergy Clin Immunol 1996;98:64-72.) Evidence strongly suggests that the prevalence and severity of asthma is increasing, especially in children, in spite of the availability of effective treatment. 1 House dust mite allergens are a major cause of asthma worldwide, and 45% to 85% of patients with asthma in the United Kingdom show skin test reactivity to mites, as compared with 5% to 30% in the general population. 2 The importance of early exposure to mite allergen in primary sensitization has been suggested by recent studies. Household exposure to levels of Der p 1 greater than 2 Ixg/gm of dust J ALLERGY CLIN IMMUNOL Custovic et al. 65 VOLUME 98, NUMBER 1 Abbreviations used BHR: Bronchial hyperresponsiveness CL: Confidence limits DRR: Dose-response ratio GM: Geometric mean PEFR: Peak expiratory flow rate
Building Services Engineering Research and Technology, 2003
This paper is concerned with historical changes in domestic ventilation and vapour dissipation rates and the associated risk of dust mite colonisation. A controlled trial evaluated allergen and water vapour control measures on the level of house dust mite (HDM) Der pI allergen and indoor humidity, concurrently with changes in lung function in 54 subjects who completed the protocol. MHRV units reduced water moisture content in the active group by an average of 12% while HDM allergen reservoirs in carpets and beds were reduced by over 96%. Self reported health status confirmed a significant clinical improvement in the active group. The study can form the basis for minimum winter ventilation rates that are likely to inhibit dust mite colonisation and activity in maritime/temperate climatic regions.
Clinical <html_ent glyph="@amp;" ascii="&"/> Experimental Allergy, 2001
Background Airway inflammation in asthma causes symptoms, airflow limitation and bronchial hyper-responsiveness. The strategy of asthma management is to reduce airway inflammation by drug treatment and avoidance of triggers, including allergens. Objective We determined the effect of exposure to house dust mite (HDM) allergens on bronchial responsiveness in asthmatics sensitive to mites while under optimal drug treatment. Methods We studied 71 mild to moderate HDM-sensitive asthmatics. Drug treatment sufficient to keep asthma under control was administered to each patient for 1 year. Subjects were divided into two groups, according to the amount of Der p 1 in their bedrooms measured after standard HDM reduction measures: low Der p 1 exposure (0.64^0.5 mg/g dust) (Group 1, n 34) and high Der p 1 exposure (12.5^11.4 mg/g) (Group 2, n 37). Bronchial responsiveness to methacholine (PD20FEV 1 ) was determined at the beginning and end of the study. Results In Group 1, PD20FEV 1 increased 2.15-fold at the end of the study from 57 to 123 mg (P , 0.05), whereas in Group 2 no significant changes were observed. The subjects in Group 2 tended to increase the use of inhaled steroids and bronchodilators in the autumn months compared with subjects in Group 1, but the difference was not significant. Conclusion This long-term study shows that exposure to lower levels of mite allergens in the bedroom is associated with a decrease of bronchial hyper-responsiveness in sensitized asthmatic subjects under optimal drug treatment.
Environmental intervention for house dust mite control in childhood bronchial asthma
Environmental Health and Preventive Medicine, 2012
Objectives This study was carried out to determine the effectiveness of physical and chemical environmental control measures for house dust mites (HDM) in controlling bronchial asthma in children. Methods A total of 160 asthmatic children who were sensitized to HDM underwent clinical and environmental assessment. The children were randomly allocated into one of four groups according to the intervention (chemical, physical, both chemical and physical, none) and the effectiveness of the intervention was assessed at 8 and 16 weeks. Results The group for which physical control measures were used showed significant improvement in all outcome measures, including mean differences of forced expiratory volume after 1 s (FEV1) and peak expiratory flow rate (PEFR), which were 2.05% and 4.65 l/min, respectively, at the 8-week follow-up evaluation. The percentage of severe asthma decreased from 45 to 22%. Similar results were obtained for the group with both chemical (tannic acid) and physical interventions (p \ 0.05 for all measures). In the group where tannic acid was used as a chemical measure, the number of children with moderate and severe asthma decreased from 15 in each category to 11 and 7, respectively. In the control group, only the mean difference of PEFR (1.62 l/min) was significant after 16 weeks. Despite these promising findings, only the FEV1 was significantly different (p = 0.014) when the four groups were compared. Conclusions Based on these results, we conclude that simple physical control measures have the potential to contribute to the control of asthma symptoms in asthmatic children sensitized to HDM allergen.
Domestic control of house dust mite allergen in children’s beds
Journal of Allergy and Clinical Immunology, 2000
Background: House dust mite allergen levels in humid coastal regions of Australia are high, particularly in beds. Because high allergen levels in beds are associated with more severe asthma, reduction of levels may be important for asthma control. Objective: We tested the effectiveness of an acaricidal treatment of bedding in combination with occlusive mattress and pillow encasings in reducing allergen levels in children's beds in a community setting. Methods: A total of 14 beds of children were selected for the active intervention. In each home the bed of a sibling of nearest age was selected as the control. Dust was vacuumed from beds by using a standard protocol, and Der p 1 levels were measured by using ELISA. Adjacent settling dust was collected by using opened Petri dishes. The intervention consisted of encasing mattresses and pillows in occlusive covers and washing all bedding with Acaril, an acaricidal additive. The acaricidal wash was repeated twice in 7 households at 2-month intervals. Control beds were not treated. Results: The mean Der p 1 concentration at baseline was 27.9 µg/g in the active beds and 18.1 µg/g in the control beds. At 4 days after intervention, Der p 1 decreased to 3.2 µg/g and 15.7 µg/g in active and control beds, respectively. The average difference (active minus control) over the first 8-week cycle was 78.5% (P < .0001), and the difference over 3 washing cycles was 125.1% (P < .05). The mean rate of settling Der p 1 adjacent to the actively treated beds decreased from 24.4 ng·m -2 ·d -1 at baseline to 10.0 ng·m -2 ·d -1 after intervention (P < .01). Conclusion: A substantial reduction in Der p 1 levels in beds and in airborne dust in a humid region with naturally high house dust mite allergen levels can be achieved and sustained in a community setting with use of occlusive covers and a rigorous washing routine. (J Allergy Clin Immunol 2000;105: 1130-3.)
House Dust Mites Avoidance and Allergic Children: A Prospective Study of a New Strategy
Clinical and Molecular Allergy, 2014
Background: Dust mites are a frequent cause of allergic rhinitis in children. Reduction of exposure seems to be the most logical way to treat these patients even if its effectiveness is controversial. Objective: Our aim was to investigate whether a new strategy, attracting and trapping house dust mites outside the mattresses with a new type of device can reduce the symptoms of allergic children. Methods: In a prospective study, mattresses were treated with a new type of trapping device. The principle of the device is to attract mites outside mattresses, to take them away and to kill them without insecticides. This trapping device was given to 40 children with moderate to severe house dust-mite allergy. Inclusion criteria were a positive RAST to the house dust-mite antigen or to the allergy skin tests. Severity of symptoms was estimated after two weeks by an established score. The results were observed after two uses of the trapping device (2 weeks). Results: All patients completed the trial. No side effects were observed. At the end of the study, a significant reduction in allergic symptoms was observed. After patients had two uses of the trapping device, significant differences were observed for the nasal congestion, sneezing, nasal itching and ocular itching. No significant difference was observed for the rhinorrhea. The percentages of patients strongly affected by their allergy (with severe or moderate symptoms) and who had mild or none symptoms after two uses of the device were 70% for the nasal congestion, 47% for the sneezing, 62% for the nasal itching, 60% for the ocular itching, and 62% for the rhinorrhea. Conclusion: Using the trapping device, commercialized under the name of Acar'up ® , produced significant and beneficial effects on symptomatology. These results encourage proceeding on this path in the choice of the therapy for those subjects affected by respiratory allergopathy to house dust mites.