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- Dust Mites -
9/24/04 re: Effects of UV-light on dust mites I am the nurse specialist/clinical coordinator for a large community-based health initiative in Central Harlem. Recently a company offered to donate some of their services to families enrolled in our program. This company uses ultraviolet treatment to kill dust mites in mattresses and bedding. I am not familiar with this treatment, and I was unable to find any articles about this method. To your knowledge, is there any scientific data to support this method of killing dust mites? I was not personally aware of any data concerning UV light effects on dust mites. Therefore, I consulted Dr. Peyton Eggleston, an expert in the environmental control of dust mites and other indoor allergens. I had to await his response which is now enclosed below.
Dr. Eggleston's response:
Ultraviolet light is known to damage or kill living organisms, so, theoretically artificial light could kill house dust mites and reduce the allergens that they produce. High intensity UV light modifies proteins as well, so it is possible that UV light might render an allergen contaminated sheet non-allergenic. Having said that, I am not aware that anyone has actually demonstrated that UV light changes allergens-no matter how intense the UV light. An Australian investigator demonstrated that airing blankets in the sunlight killed house dust mites, but he also measured temperature and humidity in the blankets. Mites are killed by high temperatures and low humidity, and he demonstrated that the temperature and humidity in the blankets could have explained the mite death that he observed. So the bottom line is that it is possible for UV light to decrease house dust mite allergen, but there is no proof that it actually does.
5/27/03 re: Quality of different types of encasing material used in dust mite avoidance programs I am looking for some information on recommended products for allergen avoidance, in particular allergen impermeable mattress and pillow covers. The American Lung Association web site has an affiliation with National Allergy Supply, yet my local Lung Association recommends the Priorities product line, which costs about three times greater. Both offer a variety of materials, from cotton-poly blends to micro fiber, also varying in costs. Local medical supply companies offer another variety.
How does one best make a recommendation to patients? Are there criteria for evaluating the best material and product, at a reasonable cost? Are there recommended manufacturers or vendors?Pardon the slight delay in responding to your question. I was awaiting input I had requested from Dr. Peyton Eggleston of Johns Hopkins Medical Institutions, an expert in allergen avoidance approaches. Dr. Eggleston's response is enclosed below. I have also enclosed a reference to a review article about allergen avoidance by Dr. Eggleston which was part of the supplement to which Dr. Eggleston referred in his response.
Dr. Eggleston's response:
Not only are there excellent products available through the web and 800 numbers, but it is possible to find them in large outlet stores such as Walmart and Target. In particular, excellent allergen-proof mattress and pillow encasings are pretty widely available. These were carefully studied in a publication by Vaughan and colleagues in the Journal of Allergy and Clinical Immunology 199;104:1079-83 and they found that most of the non-woven materials and the higher quality cotton weaves were excellent. They did not test the luxury weave sheets and pillows (280 count and higher) but they would probably compare well to the very tight weaves that they did test. Whatever is used should be washed periodically (monthly). A supplement to the Journal in March 2001 contained a complete discussion of the current data and guidelines for the control of indoor allergen exposure.
Peyton A. Eggleston, MD
Professor of Pediatrics
Johns Hopkins University
J Allergy Clin Immunol 2001 Mar;107(3 Suppl):S403-5
Environmental allergen avoidance: an overview.
Eggleston PA, Bush RK; American Academy of Asthma, Allergy and Immunology.
Department of Pediatrics, Johns Hopkins Hospital, Baltimore, MD, USA.11/5/02 re: Availability of acaricides in the USA I am a medical doctor, pulmonologist from Buenos Aires, I want to know about the use of acaricides in children’s rooms and if they are approved by the FDA. There are acaricides such as Acarosan available for use in the USA but I am not sure whether they are subject to FDA review since they are not considered therapeutic agents administered to the patient. They are not listed in the Physician's Desk Reference, a publication that lists almost all FDA-approved treatment agents.
With regard to your question about the use of acaricides in a child's room, I should say that most experts feel that acaricides should not be used first in the control of dust mite allergens. This is because their use is not cost-effective, when compared to simpler measures. I have enclosed below a relatively recent Quiz of the Month I wrote for this AADMC website that discusses this situation (Reference # 1). I have also enclosed my review of a very good article by Tovey, discussing this subject which I cited in the Quiz of the Month item (Reference #2). Also enclosed is my review of a subsequent article by Tovey's group in Australia suggesting that incorporation of a particular acaricide (available in Australia as Acaril) in the laundry wash water will reduce dust mite allergen levels in the washed bedding (Reference #3).Reference #1 Quiz of the Month - 12/01
Your 28 year old patient with prominent perennial allergic rhinitis is very sensitive to house dust mites (HDM) in allergy skin test testing. Which of the environmental approaches listed below should be the first one recommended in such a case?
1. Encase the mattress and pillows in impermeable covers and wash all bedding regularly in hot (130 degree F) water
2. Have an electrostatic filter device placed in the forced air system
3. Install air ionizer devices in the bedroom and other frequently used rooms.
4. Use a high-efficiency particulate air (HEPA) filter-equipped vacuum cleaner.
5. Treat all fabrics with a tannic acid-based acaricide to kill the dust mites
CORRECT ANSWER- #1
Discussion: A major source of HDM allergens is the bedding contents, including mattress, pillows, sheets, blankets and bedcovers. Therefore, the
most cost-effective approach to HDM avoidance is to cover the mattress and pillows and to wash all the other bedding materials in water hot enough to kill the HDM (>130 degrees F) (1). Because the HDM can live and grow in the skin scales shed by all of us when moving around in bed, such washing of bedding must be repeated on a regular basis. When items are not washable, one can try putting them in the clothes dryer at the hottest setting for 1 hour (assuming that the fabrics will tolerate such an exposure). Such dryer exposure is fairly effective at killing the HDM but will not get rid of residual HDM allergen as would occur in the clothes washer. Therefore, this "dryer" approach is best used on newly used, but not old, bedding items.
Air filtration systems, whether employing electrostatic or HEPA filters, are of only limited value in reducing the HDM allergen content of the house dust, This is because the HDM allergen is predominantly located on surfaces and is suspended in the air only transiently, mostly in the air immediately around the sites where the HDM on the surface are disturbed. Therefore, only a small minority of the HDM allergen load is suspended in the air long enough to be removed by air filtration devices. Use of a tightly fitting HEPA filter-equipped vacuum cleaner will likely reduce HDM levels if used frequently on rugs and carpets. However, such vacuuming is not as effective in reducing overall HDM. levels as removing all fabric floor coverings such as carpets and rugs.
I know of no convincing evidence that air ionizers significantly reduce the HDM content in household dust samples.
As pointed out by Tovey in his review of HDM avoidance/control
measures (1), use of acaricides containing tannic acid result in only modest and transient reductions in HDM levels. Because such acaricide treatment must be done relatively frequently, a sizable expense is incurred with this approach. Therefore, one would reserve use of such agents only for situations where simpler approaches are not sufficient.
1. J Allergy Clin Immunol 1999;103:179-91
Reference #2 Methods and effectiveness of environmental control
Summary
There has been great interest in and emphasis on the sensitization to aeroallergens such as housedust mite (HDM) as a risk factor in asthma. It is generally (but not universally) agreed that effective HDM avoidance measures will improve asthma outcomes in HDM-sensitive individuals. But what measures are most effective? This subject was reviewed by Tovey et al of the University of Sydney in Australia. They stressed that avoidance measures related to bedding is most important with suitable encasements, washing sheets/blankets at >130â F (to both kill the HDM and wash away allergens. Removal of floor covering and frequent wet washing of smooth floors is also helpful. Chemical treatment of carpets is expensive and generally insufficiently effective in lowering HDM allergen levels to non-pathogenic levels. Vacuuming with tightly sealed units, good filters and double-thickness bags may yield modest additional benefit. Air filtration generally does not add much for HDM removal because of the short time that HDM allergenic particles are airborne after each air disturbance. Air filtration can be more effective in removing furry pet allergens but the clinical benefit of this is debatable.
Reference
J Allergy Clin Immunol 1999;103:179-91
Editor's Comments
We have reviewed a number of studies in this area (see Current Literature Section). I found this one of the best, well-balanced reviews of this subject in which there is sometimes more enthusiasm and advertising "hype" than solid documentation. As the authors point out, acaricide sprays and other devices reputed to reduce allergen levels within the home are being increasingly marketed. Many measures are time consuming and expensive and of doubtful efficacy. This review is worth reading before advising patients!
Reference #3 Control of mite allergens in children's bed
Summary
It is now recognized that beds are a major source of dust mite allergen (DMA), one of the most important indoor aeroallergens. Levels of DMA are frequently a risk factor in atopic asthmatics. Current methods (use of occlusive encasements for mattress and pillow; washing bedding at high (>120¦ F) temperatures) will partially reduce DMA levels in beds. In their study, Vanlaar et al of the University of Sydney in Australia have found that periodic washing of bedding in water containing Acaril, an acaricide, will significantly reduce DMA levels further, as detected by an ELISA technique.
Reference
J Allergy Clin Immunol 2000;105:1130-3
Editor's Comments
These findings by a highly experienced group investigating control of
indoor aero allergens may be very important. However, it is not yet clear how much added benefit the use of Acaril conveys. In a review published in 1999, Dr. Tovey, the senior member of this group, concluded that acaricides in general offered little added benefit in the reduction of DMA if other measures ( reduction of humidity ,removal of all floor coverings, encasements of mattresses/pillows and hot temperature washing of bedding) were already being carried out. Perhaps acaricides do have a role in the washing of bedding in their relatively humid environment in Sydney, Australia.
10/29/01 re: Value of Aller-Rx as an acaricide Does anyone have any experience or knowledge of good studies looking at the spray called Aller-Rx, touted to be as good as or better than tannic acid for allergen denaturalization, without the problem of staining? The "studies" accompanying their literature appear to be all internally generated. I have not seen ads for Aller-Rx for some time and do not know the constituents of this product. However, I should say that highly respected investigators of the environmental control of dust mites such as Tovey have concluded that chemical treatments of fabrics to kill dust mites or denature their allergens add relatively little benefit (considering the time and expense involved) if appropriate removal of floor coverings, mattress and pillow encasement and laundering practices have been carried out (see enclosed review by me of Tovey's review article). Other groups have come to the same conclusions (see enclosed abstract). Since the review by Tovey, his group has reported that laundering fabrics at high temperatures with detergents or the agent Acaril are more effective than soap washing (see enclosed abstracts). Therefore, I would have to conclude at this time that the emphasis should be on avoidance and laundering approaches, reserving any chemical treatment of fabrics for only those cases where the mite allergen levels cannot be reduced sufficiently by the former measures. There has been great interest in and emphasis on the sensitization to aeroallergens such as house dust mite (HDM) as a risk factor in asthma. It is generally (but not universally) agreed that effective HDM avoidance measures will improve asthma outcomes in HDM-sensitive individuals. But what measures are most effective? This subject was reviewed by Tovey et al of the University of Sydney in Australia. They stressed that avoidance measures related to bedding is most important with suitable encasements, washing sheets/blankets at >130â F (to both kill the HDM and wash away allergens. Removal of floor covering and frequent wet washing of smooth floors is also helpful. Chemical treatment of carpets is expensive and generally insufficiently effective in lowering HDM allergen levels to non-pathogenic levels. Vacuuming with tightly sealed units; good filters and double-thickness bags may yield modest additional benefit. Air filtration generally does not add much for HDM removal because of the short time that HDM allergenic particles are airborne after each air disturbance. Air filtration can be more effective in removing furry pet allergens but the clinical benefit of this is debatable.Methods and effectiveness of environmental control
Summary
Reference
J Allergy Clin Immunol 1999; 103:179-91Editor’s Comments
We have reviewed a number of studies in this area (see Current Literature Section). I found this one of the best, well-balanced reviews of this subject in which there is sometimes more enthusiasm and advertising "hype" than solid documentation. As the authors point out, acaricide sprays and other devices reputed to reduce allergen levels within the home are being increasingly marketed Many measures are time consuming and expensive and of doubtful efficacy. This review is worth reading before advising patients!J Allergy Clin Immunol 1998 Apr; 101(4 Pt 1): 451-6
The Melbourne House Dust Mite study: long-term efficacy of house dust mite reduction strategies.
Sporik R, Hill DJ, Thompson PJ, Stewart GA, Carlin JB, Nolan TM, Kemp AS, Hosking CS.
Department of Allergy, Royal Children's Hospital, Melbourne, Victoria, Australia.: Asthma severity among mite-sensitized individuals appears to be related to the degree of mite allergen exposure.Background
Objectives: 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.
J Allergy Clin Immunol 2001 Sep; 108(3): 369-74
Effectiveness of laundry washing agents and conditions in the removal of cat and dust mite allergen from bedding dust.
Tovey ER, Taylor DJ, Mitakakis TZ, De Lucca SD.
Institute of Respiratory Medicine, Royal Prince Alfred Hospital, Australia.There is limited information about the removal of allergens by laundry washing.Background:
Objective: The purpose of this investigation was to determine the dynamics of the removal of mite allergen (Der p 1) and cat allergen (Fel d 1) from bed dust during simulated laundry processes.
Methods: Three studies were performed. The first compared combinations of 4 laundry agents (water alone, soap, detergent with enzymes, and detergent without enzymes), 4 temperatures (15 degrees, 25 degrees, 45 degrees, and 60 degrees C), and 3 extraction times (5, 20, and 60 minutes). The second study examined allergen extraction by 11 common brands of detergents at 25 degrees and 45 degrees C for 5 minutes. The third study compared 4 detergents containing enzymes before and after the denaturation of their enzymes. To measure the quantity of allergens extracted, each study used an ELISA assay as well as a more sensitive but semiquantitative Halogen immunoassay to detect any allergens remaining after the simulated laundry extraction.
Results: Study 1 showed that detergents extracted more of both Fel d 1 and Der p 1 than either soap or water alone and that almost all allergens were extracted within 5 minutes at 25 degrees. However, washing at 60 degrees C extracted slightly more Fel d 1 and denatured Der p 1, resulting in lower residual amounts of both allergens. Study 2 showed that all of the commercial detergents performed similarly. Study 3 showed that the presence of enzymes in detergent formulations did not produce a significant effect on the extraction of allergens.
Conclusion: Using detergent solutions at 25 degrees for at least 5 minutes was sufficient to extract most mite and cat allergen from dust of bedding
Control of mite allergens in children's bedding
Summary
It is now recognized that beds are a major source of dust mite allergen (DMA), one of the most important indoor aeroallergens. Levels of DMA are frequently a risk factor in atopic asthmatics. Current methods (use of occlusive encasements for mattress and pillow; washing bedding at high (>120¦ F) temperatures) will partially reduce DMA levels in beds. In their study, Vanlaar et al of the University of Sydney in Australia have found that periodic washing of bedding in water containing Acaril, an acaricide, will significantly reduce DMA levels further, as detected by an ELISA technique.Reference
J Allergy Clin Immunol 2000; 105:1130-3Editor’s Comments
These findings by a highly experienced group investigating control of indoor aero allergens may be very important. However, it is not yet clear how much added benefit the use of Acaril conveys. In a review published in 1999, Dr. Tovey, the senior member of this group, concluded that acaricides in general offered little added benefit in the reduction of DMA if other measures (reduction of humidity, removal of all floor coverings, encasements of mattresses/pillows and hot temperature washing of bedding) were already being carried out. Perhaps acaricides do have a role in the washing of bedding in their relatively humid environment in Sydney, Australia.Drying kills dust mites
Summary
There has been great emphasis on reduction of bedroom exposures to dust mites, a risk factor for asthma in sensitive individuals. Previous studies have shown that washing bedclothes in hot water (>120â F) will kill dust mites. In this study, Fitzharris et al of the Wellington School of Medicine in New Zealand have shown that tumble drying at maximum temperature setting for one hour will kill the great majority of dust mites in comforters as well as blankets. However, the levels of dust mite allergens are not reduced. Thus, high temperature drying can be a partial approach to environmental mite exposure.Reference
J Allergy Clin Immunol 1999; 104:499-500Editor’s Comments
This report provides useful information but also highlights the fact that reduction of mite allergen levels in bedding require both killing the live, multiplying mites and denaturing their protein to reduce allergenicity. There are chemical agents available to carry out such allergen denaturation, which could conceivably be used in a 2 pronged attack on mites (assuming that these chemicals do not damage bedding material). However, what may be a better, more cost-effective approach is to periodically dry at high heat all blankets and comforters starting soon after items such as bedding are purchased and before a large population of mites has accumulated.6/01 re: Dust mite control for furniture I am a pharmacist in Louisiana, and yesterday I had a customer ask me a question I couldn't answer. It seems they are having a hard time controlling dust mites in their apartment, not upstairs in the bedrooms, where they have covered pillows, mattresses, etc, but downstairs. They have pulled up the carpet and installed tile, but don't know what to do about the sofa. They have used foggers but need to know what they can use to treat the sofa. Any suggestions? The only product I have heard of for dust mites was a powder used on carpeting. Any information you can provide would be greatly appreciated. There has been considerable debate among investigators whether chemical treatment of carpets and furniture really adds sufficient benefit in living rooms to the generally accepted measures of
- removing carpets and rugs and
- avoiding use of overstuffed furniture unless the latter are covered with impermeable covers which are washed regularly. Reduction of the relative humidity to <50% a tall times is also very important. Therefore, accurate monitoring of the relative humidity and resultant use of a dehumidifier, if indicated, will be very helpful. I have enclosed below my reviews of several articles by leading investigators in this field which will give more detail.
Most investigators have concluded that agents which either kill the dust mites (acaricides) or denature the dust mite allergen yield only modest additional benefit which last only a few months. Therefore, the repeated use of such agents in several rooms can become quite expensive. In a report by Tovey's group from Sydney, Australia in the year 2000 (see below), they found that washing clothes in water containing Acaril, an acaricide, was particularly helpful in their humid environment. This agent might be useful in treating soft furniture. I do not know whether this product is available in your location. Investigators in the USA and the UK have used Acarosan (containing benzyl benzoate), on soft furniture. However, others have concluded that use of Acarosan yielded only modest additional benefit.
Long-term efficacy of dust mite control measure
Summary
Several experts in allergen avoidance have stressed the importance of removal of carpets in dust mite control measures. (See Allergy Update #2 in the News Section). Yet many patients/parents are reluctant to carry out such removal and look for other viable approaches to reduce mite allergen concentrations. Sporik et al of the Royal Children's Hospital, Melbourne, Australia have reported that use of an "anti-mite" shampoo on carpets did not reduce mite allergen concentrations in carpets any more than a placebo shampoo. In contrast removal of carpet was associated with a 10 fold decrease in mite allergen levels in the rooms studied.Reference
J Allergy Clin Immunol 1998;101:451-56Editor's Comments
This report emphasizes what is becoming generally agreed. Even when shampoos or other applications do reduce mite numbers on allergen concentrations in a bedroom such reduction is transient and modest in degree - not enough to reduce mite allergen-induced symptoms. Also, these treatments are not inexpensive when a sizable room is involved.
Methods and effectiveness of environmental control
Summary
There has been great interest in and emphasis on the sensitization to aeroallergens such as house dust mite (HDM) as a risk factor in asthma. It is generally (but not universally) agreed that effective HDM avoidance measures will improve asthma outcomes in HDM-sensitive individuals. But what measures are most effective? This subject was reviewed by Tovey et al of the University of Sydney in Australia. They stressed that avoidance measures related to bedding is most important with suitable encasements, washing sheets/blankets at >130â F (to both kill the HDM and wash away allergens. Removal of floor covering and frequent wet washing of smooth floors is also helpful. Chemical treatment of carpets is expensive and generally insufficiently effective in lowering HDM allergen levels to non-pathogenic levels. Vacuuming with tightly sealed units, good filters and double-thickness bags may yield modest additional benefit. Air filtration generally does not add much for HDM removal because of the short time that HDM allergenic particles are airborne after each air disturbance. Air filtration can be more effective in removing furry pet allergens but the clinical benefit of this is debatable.Reference
J Allergy Clin Immunol 1999;103:179-91Editor's Comments
We have reviewed a number of studies in this area. I found this one of the best, well-balanced reviews of this subject in which there is sometimes more enthusiasm and advertising "hype" than solid documentation. As the authors point out, acaricide sprays and other devices reputed to reduce allergen levels within the home are being increasingly marketed Many measures are time consuming and expensive and of doubtful efficacy. This review is worth reading before advising patients!
J Allergy Clin Immunol 2000 Feb;105(2 Pt 1):252-8
Manchester Asthma and Allergy Study: low-allergen environment can be achieved and maintained during pregnancy and in early life.
Custovic A, Simpson BM, Simpson A, Hallam C, Craven M, Brutsche M, Woodcock A.
North West Lung Centre, Wythenshawe Hospital, Manchester, United Kingdom.Background: Early exposure to dust mite allergens may be critical for primary sensitization. Reducing exposure may offer a realistic chance for primary prevention of sensitization and asthma, but it is essential to implement measures that can achieve and maintain the low-allergen environment.
Objective: Our purpose was to assess the effectiveness of mite allergen avoidance measures in achieving and maintaining a low-allergen environment during pregnancy and in the first year of life.
Methods: The Manchester Asthma and Allergy Study is a prospective, prenatally randomized study that follows the development of asthma and atopy in a cohort of infants at high risk (both parents atopic) who are randomly allocated to full mite allergen avoidance or to a normal regimen. Avoidance measures comprise (1) mite-proof covers (mattress, pillow, and quilt) for parental bed, (2) high-filtration vacuum cleaner, (3) vinyl flooring in infant's bedroom, (4) new crib and portable crib mattresses encased in mite-proof material, (5) benzyl benzoate (Acarosan) applied on carpets and soft furniture, (6) bed linens washed in hot water weekly, and (7) washable soft toys. Dust samples from the parental bed, bedroom floor, living room floor, infant's mattress, and nursery floor were collected between the 10th and 14th weeks of pregnancy, immediately after birth, and then at age 6 months and 1 year, and Der p 1 levels were determined by mAb-based ELISA.
Results: Recovered Der p 1 from maternal mattress was reduced by 97. 25% (95% confidence interval [CI] 95.25%-98.41%) during the second and third trimesters of pregnancy, with the effect persisting for 6 months (98% reduction, 95% CI 97.25%-99.1%) and 12 months (97.6% reduction, 95% CI 95.7%-98.6%) after the birth (active vs control, P <.000001). Total Der p 1 from bedroom floor in the active group was reduced by 53.7% (95% CI 25.7%-71.2%) in samples collected within 4 weeks of the child's birth, with the percentage reduction being 62. 8% (95% CI 39.3%-77.2%) at 6 months and 26.5% (95% CI -24% to 57.1%) at 1 year (active compared vs control, P <.007). Der p 1 levels in crib mattress and nursery floor in the active group were extremely low (crib mattresses geometric mean [95% CI] 2.3 ng [1.6-3.4] at birth, 6.8 ng [4.5-10] at age 6 months, and 15.6 ng [9.8-24.8] at age 1 year [active vs control, P =.001]; nursery 1 ng [0.9-1.1] at birth, 1.7 ng [1.2-2.5] at age 6 months, and 2 ng [1.3-3.5] at age 1 year [active vs control, P <.00001]). The total amount of allergen recovered at age 1 year was 29-fold (95% CI 15.1- to 56.7-fold) higher in the control group than in the active group.
Conclusions: The avoidance measures used in this study achieved and maintained a low mite allergen environment during pregnancy and in the first year of life in homes of infants at risk of atopy.
Clin Exp Allergy 1999 Oct;29(10):1336-46
Effects of house dust mite avoidance measures on Der p 1 concentrations and clinical condition of mild adult house dust mite-allergic asthmatic patients, using no inhaled steroids.
Cloosterman SG, Schermer TR, Bijl-Hofland ID, Van Der Heide S, Brunekreef B, Van Den Elshout FJ, Van Herwaarden CL, Van Schayck CP.
Department General Practice and Social Medicine, University of Nijmegen, Nijmegen, The Netherlands.Background: Exposure to house dust mite (HDM) allergens often results in worsening of asthma. Therefore, avoidance of exposure to HDM allergens is often proposed. Unfortunately, the most effective and feasible avoidance strategy is still not completely assessed. Consequently, we investigated the effects of a combined HDM avoidance strategy on HDM allergen concentrations and clinical condition of allergic, mild asthmatic, patients using no inhaled steroids.
Methods: Asthmatic patients, allergic to HDM, using no inhaled corticosteroids, were randomly allocated to an active (n = 76) or a placebo allergen-avoidance group (n = 81). Avoidance measures consisted of applying Acarosan(R) (placebo: water) to the living room and bedroom floors, and the use of HDM-impermeable covers for mattresses and bedding (placebo: cotton covers for mattresses only). Effects on allergen concentrations (Der p 1), FEV1, bronchial hyperresponsiveness, peak flow parameters and asthma symptom scores were studied during 20 weeks and controlled for the allergic status of the patients.
Results: The active covers reduced Der p 1 concentrations to 9.4% (P = 0.0001), and were always significant lower than in the placebo group (P = 0.0002). Acarosan(R) resulted in slight but significant decreases (twofold, P = 0.0001), both on living room and bedroom floors, but concentrations were never significantly lower than the placebo group. Although the combined avoidance strategy resulted in a considerable reduction in allergen load in the active group, no differences were seen between the two groups in any of the clinical parameters during the follow-up period in this group of allergic asthmatics, using no inhaled corticosteroids. Corrections for the allergic status did not alter these results.
Conclusions: The combined avoidance strategy was effective in reducing HDM allergen concentration. This was especially achieved by the allergen-impermeable covers, while the effects of Acarosan(R) were only marginal. However, this allergen reduction was not reflected in a convincing improvement in clinical condition in this group of mild allergic asthmatics, using no inhaled steroids. Perhaps, a longer follow-up period would have resulted in more pronounced effects.
