House Dust Mite Allergen Avoidance Research Articles

What's new in atopic dermatitis?

What's new in atopic dermatitis?

The psychrometric control of house dust mites: a pilot study

This paper describes a pilot intervention study on the effectiveness of house dust mite allergen avoidance for 12 asthmatic children (two being controls). In addition to mite allergen removal, the study included tailored advice aimed at reducing mite population growth via changes in moisture production, heating and ventilation habits. This paper focuses on the effects of this advice on household behaviour, hygrothermal conditions and mite populations. The efficacy of monitoring and modelling techniques is also discussed. The study highlighted a number of interrelated confounding factors which have to be addressed in future similar larger scale studies, but the results are promising with regards to the effectiveness of such studies. Practical application: This study suggests that in temperate climates tailored advice on moisture production, heating and ventilation habits can lead to valuable changes in hygrothermal conditions, which in turn can result in reduced mite populations. However, pre-existing adverse building conditions may hinder such changes, and the effectiveness of tailored advice and of hygrothermal modifications is often difficult to assess. It is therefore recommended that any similar larger intervention study measures ventilation rates and adequately controls for a number of confounding variables — including the effect of changes in outdoor conditions and of the removal of existing mite populations. In this respect, hygrothermal population models can play a very useful role in the assessment of study effectiveness.

Prevention of allergic disease during childhood by allergen avoidance: The Isle of Wight prevention study

Early life allergen exposure may increase the risk of childhood allergy, but the protective effect of reduction in allergen exposure remains uncertain. To evaluate the effect of reduction in food and house dust mite (HDM) allergen exposure in infancy in preventing asthma and allergy. Infants, at higher risk because of family predisposition, were recruited prenatally and randomized to prophylactic (n = 58) and control (n = 62) groups. Prophylactic group infants were either breast-fed with mother on a low allergen diet or given an extensively hydrolyzed formula. Exposure to HDM was reduced by the use of an acaricide and mattress covers. The control group followed standard advice. Development of allergic diseases and sensitization to common allergens (atopy) was assessed blindly at ages 1, 2, 4, and 8 years in all 120 children. Repeated measurement analysis, adjusted for all relevant confounding variables, confirmed a preventive effect on asthma: adjusted odds ratio (OR), 0.24; 95% CI, 0.09-0.66; P = .005; atopic dermatitis, OR, 0.23; CI, 0.08-0.64; P = .005; rhinitis, OR, 0.42; CI, 0.19-0.92; P = .03; and atopy, OR, 0.13; CI, 0.05-0.32; P < .001. The protective effect was primarily observed in the subgroup of children with persistent disease (symptoms at all visits) and in those with evidence of allergic sensitization. Allergic diseases can be reduced, for at least the first 8 years of life, by combined food and HDM allergen avoidance in infancy. Strict food and HDM allergen avoidance should be considered for prevention of allergy in high-risk infants.

Three-year outcomes of dietary fatty acid modification and house dust mite reduction in the Childhood Asthma Prevention Study

Two factors thought to influence the risk of asthma are the promoting effect of sensitization to house dust mites and the preventive effect of increased omega-3 fatty acids. Although house dust mite allergen avoidance has been used as a preventive strategy in several trials, the effect of omega-3 fatty acid supplementation in the primary prevention of asthma and allergic disease is not known. To measure the effects of dietary supplementation with omega-3 fatty acids and house dust mite allergen avoidance in children with a family history of asthma. A total of 616 children at high risk of asthma were enrolled antenatally in a randomized controlled trial, and 526 children remained in the trial at age 3 years. The outcomes were symptoms of allergic disease and allergen sensitization. There was a significant 10.0% (95% CI, 3.7-16.4) reduction in the prevalence of cough in atopic children in the active diet group ( P=.003; number needed to treat, 10) but a negligible 1.1% (95% CI, -7.1 to 9.5) reduction cough among nonatopic children. There was a 7.2% (95% CI, 10.11-14.3) reduction in sensitization to house dust mite in the active allergen avoidance group ( P=.05; number needed to treat, 14). No significant differences in wheeze were found with either intervention. These results suggest that our interventions, designed to be used in simple public health campaigns, may have a role in preventing the development of allergic sensitization and airways disease in early childhood. This offers the prospect of reducing allergic disease in later life.

Allergen avoidance and prevention of atopy.

Recent increases in the prevalence of atopic disease argue strongly that environmental factors operating primarily in early life play a significant role. Exposure to food and inhalant allergens early in life may constitute a risk factor amenable to manipulation. Recent observational and interventional studies have produced conflicting data regarding the effectiveness of allergen avoidance in primary and secondary prevention of atopic diseases. Exclusive breast feeding for 4-6 months may protect against the development of allergic diseases in early childhood and remains good advice. Convincing proof for the preventive effects of the delayed introduction of solid foods and hydrolyzed formula in formula-fed infants is lacking. There is some evidence to support a preventive effect of house dust mite allergen avoidance before sensitization occurs. The effect of exposure to animal allergen is uncertain, with some studies showing an increase in sensitization while others suggest a protective effect. Therefore, no evidence-based advice can be given at this stage regarding allergen avoidance measures to be adopted by families with infants at high risk of atopy, except perhaps to breast feed exclusively for at least 4 months. Data regarding the secondary prevention of allergic disease by allergen avoidance were more secure until the publication this year of two randomized controlled trials which suggest that mattress impermeable covers, the main dust mite allergen avoidance measure, may not work. Allergen avoidance, however, should remain an essential part of the management of allergic diseases, even if the benefit of mattress covers is in doubt.

Dust mite allergens: mitigation and control.

In recent years, greater attention has been given to the role of indoor allergens as a cause of sensitization and allergic respiratory diseases. Although indoor allergen control measures to reduce symptoms in individuals allergic to mites have produced controversial results, environmental allergen avoidance is today one of the four primary goals of asthma management recommended in several guidelines of asthma treatment. Exposure to high indoor aeroallergen levels, especially to house dust mite allergens, is an important environmental risk factor for allergic sensitization and the subsequent development and exacerbation of asthma. Therefore, effective aeroallergen avoidance is of use to prevent and treat allergic diseases. Although endotoxin exposure may be protective in early life, it has been demonstrated that the inhalation of endotoxin may exacerbate asthma in house dust mite sensitized patients. Mite-allergic asthmatic patients should be aware of the dangerous combination of mite allergen exposure associated with high endotoxin levels in house dust. These two immunologically active substances have been associated with severe asthma and seasonal exacerbation of symptoms. Effective house dust mite allergen avoidance will never be achieved using a single control measure; various methods are required to affect the multiple factors that facilitate high indoor allergen levels. Education of the patients and their families is also an important component of environmental control strategies.

Hot tumble drying and mite survival in duvets

Exposure to the house dust mite (HDM) allergen Der p 1 has increasingly been associated with the development and exacerbation of asthma. Consequently, HDM allergen avoidance advice is included in management plans for asthma and allergic diseases. A particular focus is placed on the bedroom, where HDM allergen exposures are usually highest.1 Occlusive covers for mattresses, duvets, and pillows are effective in reducing exposure to reservoir HDM allergen, and hot-water washing (>55°C) is effective in killing HDMs.

Do Asthmatics Benefit from House Dust Mite Allergen Avoidance Strategies?: Results of a Systematic Review of the Literature ♦ 22

We conducted a systematic review to determine if asthmatics who are sensitive to house dust mites (HDM) benefit from HDM allergen avoidance strategies. Using MEDLINE, a review of bibliographies, and references supplied by international experts in entomology and pediatric allergy, we identified 764 titles of English language articles, published between January, 1966 and July, 1997, which possibly included information about allergen avoidance strategies for HDM. Two investigators (MC, PE) independently reviewed the full bibliographic citation of each of the 764 candidate articles and identified 112 articles for further review. The full text of each of the 112 articles was read by two independent reviewers (MC, JZ) to identify randomized controlled trials which met the following criteria: presence of original data, intervention duration longer than eight weeks, washout period of at least four weeks for crossover trials, and a history of asthma with objective evidence of HDM sensitivity in the study population. Differences between the reviewers were resolved by consensus (MC, JZ, PE). 18 articles met the above inclusion criteria and included one or a combination of the following interventions: chemical control measures (13 articles), impermeable covers (9), aggressive cleaning (8), and/or humidity reduction (2). Studies also varied in their exclusion of study patients (i.e. severity of asthma, pet ownership, and/or tobacco exposure), as well as selection of outcome measurements, such as HDM allergen levels (12), HDM counts (5), house dust weight (3), subjective symptom scores (9), medication use (6), physician's assessment (1), lung function tests (12) and histamine/methacholine challenge tests (10). The 18 accepted articles differed in their conclusions regarding the benefit of HDM allergen avoidance measures. We conclude that the heterogeneity of interventions, exclusion criteria, and outcome measures prevents combining data among studies to calculate overall summary measures of intervention effectiveness. Furthermore, the studies suggesting a clinical benefit are qualitatively different from negative studies, since they tend to have more explicit protocols to monitor patient compliance, and tend to exclude patients on chronic steroids, patients with recent hospitalizations, and patients who own pets.

House Dust Mite Allergen Avoidance: A Randomized, Controlled Trial of Surface Chemical Treatment and Encasement of Bedding

House Dust Mite Allergen Avoidance: A Randomized, Controlled Trial of Surface Chemical Treatment and Encasement of Bedding

House Dust Mite Allergen Avoidance: A Randomized, Controlled Trial of Surface Chemical Treatment and Encasement of Bedding

House Dust Mite Allergen Avoidance: A Randomized, Controlled Trial of Surface Chemical Treatment and Encasement of Bedding

House dust mite allergen avoidance: a randomized controlled trial of surface chemical treatment and encasement of bedding

To test the effectiveness of a house dust mite (HDM) allergen avoidance strategy we conducted a randomized controlled trial in 35 atopic subjects with asthma, aged 13 to 60 living in Sydney - a high HDM allergen environment. After a 3 month run-in period, subjects were randomized to active allergen avoidance treatment (n = 17) or placebo (n = 18) groups and followed for 6 months. The active treatment involved placing impermeable covers over the mattress, pillows and duvet and spraying the remaining bedding, as well as the carpets and furniture, with a tannic acid/acaricidal spray. Subjects kept a daily record of symptoms and peak expiratory flow rates and had 3 monthly assessments of lung function and airway hyperresponsiveness (AHR). Dust samples were collected from the bed, the bedroom floor and the living room floor at 3 monthly intervals and 2 weeks after the treatment. Mean HDM allergen levels at baseline at these sites were, in the active group, 15.5, 9.6 and 10.2 micrograms Der p I/g of fine dust, and, in the placebo group 25.7, 11.8 and 6.3 micrograms/g. Two weeks after the allergen avoidance treatment the HDM allergen level in the beds was reduced to 29% of baseline (95% CI 16-50%, P = 0.038 compared with placebo), but was not significantly different at 3 or 6 months. There was also no significant effect of the allergen avoidance treatment on symptom scores, peak flow variability, lung function or AHR P > 0.1).(ABSTRACT TRUNCATED AT 250 WORDS)