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- Allergen Avoidance -

4/3/04 re: Efficacy of Ionic Breeze device
Q.

There has recently been a lot of advertising regarding the Ionic Breeze electrostatic precipitator air cleaner Ionic Quadra, and the Ionic Breeze GP (Germicidal Protection). I recognize that these air cleaners are extemely quiet. When at the recent AAAAI meeting, I was given information by Sharper Image, the maker of these air cleaners that suggest that this product is as effective an air cleaner as a HEPA cleaner. Is there any information, in a peer-reviewed journal that would suggest that the Ionic Breeze cleaners are as effective as the HEPA cleaners in removing air borne allergens? I can reference the articles I was given by Sharper Image if you want. Thank you.

A. To help answer your question, I consulted Dr. Robert Wood of the Johns Hopkins Medical Institutions, a highly respected expert in aeroallergen control, including the use of air filtration devices. Dr. Wood's response is enclosed below. I have also enclosed below an abstract of a review of the medical uses of air filtration devices written by Dr. Wood.
_______________________________________________________________
There are no good data on the Ionic Breeze but I can give you a few impressions. Tom Platts-Mills has studied it and published a paper in Clin Exp Allergy last year in which they claim it is an excellent air sampling device. You could never get this from the paper but my impression is that it became an air sampler when it failed as an air cleaner. I would also refer you to the Consumer Reports from lastOctober in which they concluded for the second time that ionic air cleaners are of absolutely no value. I strongly encourage my patients to get a HEPA product and to stay away from the Ionic Breeze.
____________________________________________________________

Curr Allergy Asthma Rep. 2002 Sep;2(5):397-400.
Air filtration devices in the control of indoor allergens.
Wood RA.
Johns Hopkins Hospital, 600 North Wolfe Street, CMSC 1102, Baltimore, MD

There are a variety of air cleaning devices that have been developed for the control of indoor allergens and irritants. These include both portable, room-sized units, and central units for use with a home's heating and ventilation system. While air cleaners can help to reduce some allergens, such as those produced by cats and dogs, they are unlikely to work for most other indoor allergens. The use of air cleaners for the management of allergic disease is reviewed in this article, and specific recommendations for their use are provided.
10/31/01 re: Value of air filtration/ionization in respiratory allergies and asthma.
Q.

Where can I find non-commercially hyped reviews of the pros and cons of air filtration (HEPA) vs. air ionization devices?

A. Although there have been encouraging findings concerning reduction of airborne levels of certain aeroallergens by air filtration devices (see enclosed abstract below as an example), it has been difficult to find convincing evidence that these filtration approaches result in reduced severity of respiratory allergies and asthma. This situation is summarized in the enclosed paragraph below from a nice review of allergen control by Dr. Jill Warner.

Air ionization has been promoted for years as an effective adjunctive treatment of respiratory allergies. I have not been convinced of the efficacy of this approach.

One factor that may lead to unimpressive effects of air handling treatments on respiratory allergy clinical manifestations is that the major indoor aeroallergen, from dust mites, does not stay suspended in the air for very long. Rather, it is found in high concentrations on the surface of carpets, mattresses, stuffed toys, etc., being suspended only into the surrounding air when there is local disturbance of air currents by movement of us humans, animals, etc. Therefore, dust mite allergens are not persistently available in the air for effective air filtration by these devices. Thus, the relatively low levels which are persistently suspended in the air may be reduced by filtration, but this does not have a prominent effect on the majority of the allergen stores.

J Allergy Clin Immunol 1990 Jun;85(6):1050-7
Comment in:
J Allergy Clin Immunol. 1991 Jul;88(1):140
A double-blind study of the effectiveness of a high-efficiency particulate air (HEPA) filter in the treatment of patients with perennial allergic rhinitis and asthma.
Reisman RE, Mauriello PM, Davis GB, Georgitis JW, DeMasi JM.
Department of Medicine, SUNY/Buffalo, N.Y.

"This study was designed to assess the effectiveness of a high-efficiency particulate air (HEPA) filter in alleviating allergic respiratory symptoms. Thirty-two patients were studied who had symptomatic perennial rhinitis and/or asthma during the fall and winter months and had a positive skin test with house dust or house dust--mite extract. An ENVIRACAIRE room air cleaner was placed in the bedroom for 8 weeks. In a random manner, the active filter was used for 4 weeks and a blank filter for 4 weeks. There was an average 70% reduction in the particulate matter greater than or equal to 0.3 micron with the HEPA filter. In a double-blind design, results were assessed by analysis of the patients' symptom/medication scores and subjective evaluation. For the total study, there was no difference in the total symptom/medication scores or individual symptom scores during the placebo and active-filter periods. Analysis of the last 2 weeks of each filter period in which respiratory infection was absent demonstrated definite differences in total and individual symptoms, suggesting active-filter benefit. Patients' subjective responses also suggested benefit from the filter. The overall impression is that the HEPA filter can reduce allergic respiratory symptoms."

From Warner, J. - Ped Allerg Immunol. 2000;11:208-219
"Other techniques that have been investigated include: ionisers and air filtration devices. The effectiveness of all of these devices is extremely variable in reducing domestic allergens and whilst several have shown significant reductions in house dust mite allergens in specific source materials, few have been able to translate these reductions into clinical benefit. Some studies do not assess clinical benefit, purely measuring changes in allergen concentrations to assess the effectiveness of the intervention. These studies indicate potentially useful interventions, and people who are looking for techniques to reduce allergen concentrations may wish to try them in their own homes as part of an allergen-reduction schedule, but no clinical benefit has been proven. In the following sections, studies that have simply monitored allergen concentrations are reviewed first, followed by studies on clinical benefits. The effects on carpets are summarized in Table 2."
7/2/01 re: Value of cleaning ductwork in aeroallergen avoidance
Q.

Of what benefit is cleaning of the air ducts in a residential heating and air conditioning ventilation system? I have had several patients ask if it is worth the couple of hundred dollars to have the ducts cleaned to help control their (or their child's) asthma/seasonal allergic rhinitis. The only information I found was in an article which referred to the 56th annual AAAAI meeting where the cleaning of air ducts in the home to reduce animal allergens is of limited value. What about molds?
A. Most investigators of allergen avoidance measures have concluded that measures such as HEPA filtration and air duct cleaning are of only modest if any benefit in reducing the levels of dust mite allergens in rooms such as bedrooms. This is because most of the dust mite allergen is settled on the surfaces of bedding, carpets, etc. to which the person is locally exposed. The mite allergens are suspended in the air only transiently and locally around the source and are not circulated in large amounts through the air handling system of the dwelling (see the enclosed review by me of a review by Tovey et al, leading investigators of allergen avoidance. Also see my responses to previous Ask the Expert questions in this area by clicking on the "allergen avoidance" and "air filtration" key words in this Ask the Expert section). The subject of airborne mold levels is somewhat different and more complex. As you may know, it is felt that most of the molds found indoors actually come in from the outside and proliferate in areas of high humidity. Some investigators feel that markedly increase airborne mold levels may contribute to the "sick building syndrome" (see enclosed abstract). I have not seen an appropriately controlled study directed specifically to the effects of air duct cleaning on mold levels. However, I suspect that any modest benefit achieved would be not as impressive as attempts to reduce indoor relative humidity to below 50% at all times. Since high-humidity home environments frequently are secondary to wet basements, an aggressive attempt to eliminate water entry into the basement from rainstorms should be made. Use of dehumidifiers that drain into a sink or other outlet is also helpful. When mold/mildew is still present in sizable amounts, cautious use of evaporating fungicide crystals (e.g., paraformaldehyde) in a air-sealed basement room may reduce the airborne mold levels for a period of months. Any room treated in such a way should be well ventilated afterwards for at least a day before it is used. As noted in the enclosed abstract, frequent replacement of filters and cleaning of exposed parts of the air handling system with bleach-containing materials may reduce mold/fungal levels transiently. All these measures involve considerably less expense than the duct cleaning services which are aggressively marketed in some areas.

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 >130 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!

Appl Occup Environ Hyg 2000 Aug;15(8):635-43
Resolution of sick building syndrome in a high-security facility.
Hiipakka DW, Buffington JR.
U.S. Naval Hospital, Rota, Spain.

The main objective of this article is to serve as a case study for other industrial hygiene (IH) professionals' review as a "real world" effort in responding to a facility perceived as "sick" by its occupants. As many industrial hygienists do not have extensive backgrounds in evaluating microbial air contaminants or the mechanical function of building HVAC units, the overall intent is to provide "lessons learned" to IH generalists who may be asked to participate in indoor environmental quality (IEQ) surveys. In September 1994, a suspected case of "sick building syndrome" was investigated (with significant airborne fungal loads confirmed) at a communications center after numerous occupants reported upper respiratory disease and/or allergy-type symptoms. The setting was a two-story structure approximately 30 years old, with a normal occupancy load of 350 to 400 persons. In addition to continual structural modifications, the central HVAC air conditioning systems had poor maintenance histories. Inspection of HVAC components revealed visible fungal growth on air filters and air ducts and in cooling fan condensate drip pans. Fungal air samples were collected with an Anderson N6 air sampler and Sabouraund dextrose agar media. Over a study period of 23 months, three rounds of 26 air samples were collected for 5 minutes each at 28.3 liters/minute airflow. Cultures exhibited fungi such as Aspergillus, Penicillium, Alternaria, and Cladosporium. Certain strains of these fungi produce mycotoxins that may cause a variety of deleterious health effects such as those described by occupants. Initial 1994 airborne fungal concentrations ranged from 85 to 6157 colony forming units (CFUs) per cubic meter of sampled air (CFU/m3). Some investigators have reported fungal concentrations as low as 245 CFU/m3 associated with complaint sites in other buildings. Remediation efforts involved hiring a dedicated mechanic to implement a HVAC preventive maintenance program (including regular replacement of all HVAC air filters and cleaning of accessible components with water/bleach solution). Post-abatement January 1996 re-sampling revealed a significant drop in airborne fungal colonies up to 97 percent (range = 21 to 1092 CFUs/m3)—which also coincided with physicians at the local hospital sensing a qualitative reduction in patient visits from facility workers. To address seasonal bias, a final August 1996 air sample round revealed a range of 14 to 500 CFUs/m3. Of the 21 workspaces sampled in all three rounds, nine continued to show a decline in CFUs/m3 from September 1994 baseline counts. These results demonstrate the critical role of an ongoing HVAC maintenance program for reducing potential reservoirs of fungal organisms in indoor work environments. Building renovations (especially those involving major changes to building layout and usage) can adversely affect IEQ if plans do not include coordinated updates and regular preventive maintenance of HVAC systems. Eventual negative outcomes can be reduced occupant productivity and deleterious health effects.
6/01 re: Dust mite control for furniture
Q. 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.
A. 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
  1. removing carpets and rugs and
  2. 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;101:451-56

Editor'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;103:179-91

Editor'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.
11/10/00 re: Early exposure to aeroallergens
Q. Is there any clinical evidence that exposure to environmental allergens in early life reduce the chance of getting asthma later. The "hygiene hypothesis" in which exposure to infections result in the formation of Th1 cytokines at the expense of Th2 cytokines (those responsible for the asthma phenotype)?
A. Your thoughtful question is directed to an area of considerable interest and investigation.

Earlier epidemiologic studies sought to determine whether components of aeroallergens to which a pregnant woman was exposed would pass through the placenta to the fetus to either a) prime that fetus for earlier or more severe sensitivity when that individual was exposed naturally to that pollen in early childhood. or b) such in utero exposure to allergenic peptides might tolerize the fetus rather prime it. These studies actually found no increased or decreased sensitivity in the children in such cases.

More recently, it has been shown that fetal lymphocytes obtained after 20 weeks of gestation have the capacity to mount immune responses. Further, cord blood lymphocyte of some fetuses appear reactive to food allergens in vitro. Such possible priming in utero by food allergens passing through the placenta after maternal ingestion could explain the early appearance of food allergy in childhood.

Other investigators subsequently reported less impressive evidence of reactivity of fetal lymphocytes to aeroallergens. In a thoughtful editorial (JACI 2000;106:441-3) Platts-Mills et al questioned whether there was any firm evidence for such in utero priming. Points they raised include:

a) The amount of aeroallergen components entering the pregnant woman's body is likely much less than from ingested foods and probably too little to sensitize the fetus in utero

b) The laboratory findings suggesting such sensitization were quite modest and likely not relevant

c) It was unusual for atopic children to manifest clinical sensitivity to aeroallergens before the age of 2-3 years even though they had been exposed to these aeroallergens to some degree since birth. This situation differs from the early expression of food allergy in infancy and suggests that priming to aeroallergens in utero does not occur.

The last point relates to your question. If repeated exposure to aeroallergens before and after birth were to skew away from an IgE immune response to aeroallergens, one would not expect the children to exhibit such reactivity at ages 3+ years. It is likely that it takes several years to mount an IgE response to the relatively small amount of allergenic pollen proteins to which a child is exposed each year. Of interest. the usual time for an atopic adult to become clinically sensitive to a newly encountered pollen is about 3-5 years. 

To further address your question, it would be interesting to compare the incidence of IgE sensitivity to an allergen such as ragweed in older children living in a ragweed-populated region (with strong family atopic backgrounds) who:

a) Spent their in utero time and first 2 years of life in the same ragweed-populated area vs.
b) moved to this ragweed-populated area from a ragweed-free region (e.g.- California) at age 3 years.

However, I am not aware of any study of this sort.

I hope that this response in a very complex area has been helpful.

 
6/23/00 re: Prevention of allergies in infancy
Q. I am looking for information concerning prevention of food allergy development in newborns/children by mother's avoidance of allergenic food during breast feeding. What is the mechanism of this (at least sometimes) preventive measure? Are there food allergens (or parts thereof) which can pass through into the mother's milk? Does it work even with potential allergens against which the parents are not allergic?
A. Space limitation does not permit full discussion of the huge amount of information published in this area by Zeiger, Sampson and others. To answer your main questions:
  1. Breast feeding as long as feasible with delay in introduction of other foods in "increased risk" infants (parents with strong histories of allergies to foods and inhalants) will reduce the likelihood of atopic dermatitis in infancy and delay (though not absolutely prevent) development of respiratory allergies. The foods with "high allergenic potential" should be introduced last (e.g. - eggs, cow's milk, nuts, peanuts, fish, soy). Extensively hydrolyzed formulas may substitute for breast feeding if the latter is not feasible.

  2. There have been cases where food allergens are passed in breast milk to the nursing infants although the likelihood of these sensitizing the infant is less than if ingested directly by the infant. Such breast milk transfer can occur whether or not the mother is allergic. One would suppose that the mother would avoid foods for which she is known to be allergic

For more information please read the abstracts listed below.

REFERENCES:  www.medline.com 

  • J Pediatr Gastroenterol Nutr 2000;30 Suppl:S77-86
  • Acta Paediatr Suppl 1999 Aug;88(430):104-9
  • Ann Med 1999 Aug;31(4):293-8
  • Allergol Immunopathol (Madr) 1998 May-Jun;26(3):97-101

 
6/21/00 re: Housing factors in allergy avoidance
Q. What information do you have concerning the relationship between allergies/asthma & the type of home( as in type of structure) one resides in ? What is the best type home ( brick; wood; log; etc.) favorable to allergies /asthma and/or perennial/allergic rhinitis? (Pt is currently taking allergy shots; is taking numerous mdi's for seasonal asthmatic bronchitis; & is getting ready to build a new home and would like to build a home which would be easier on allergies/asthma.)
A. The answer to your question depends, of course, on the nature of the allergens to which the patient is sensitive:
  1. For example, dust mites (the most common indoor allergen) grow better in the higher (>50%) relative humidities commonly experienced in newer "more tightly sealed" houses, particularly if there is an efficient central humidification system. However, on the other hand, very dry indoor air (relative humidity <20%) often seen in non-humidified, force-air heated houses in cold weather climates, is irritating to the airways. Therefore, monitoring and adjusting humidity levels between 20 and 45% is important.

  2. Avoidance of all carpeting and large rugs will also reduce mite allergens. Any small "throw" rugs used should be hot water washable (over 120° F).

  3. See our review in the Current Lit section of this AADMC website of a very good review article about avoidance measures by Tovey (J Allergy Clin Immunol 1999;103:179-91).

  4. Because of the frequent development of cat sensitivity in atopic individuals, it is prudent to avoid keeping cats as pets. Sensitivity to dogs occurs less commonly/severely but certainly does occur in some individuals.

  5. Another advantage of smooth, washable floor covering (e.g. vinyl) is the increased efficiency in cleaning up dropped food items, especially if small children are present. Such food particles provide an excellent attractant for cockroaches, another common indoor allergen.

  6. There is considerable marketing of air filtration devices with the objective of reducing airborne levels of indoor allergens. While an efficient filtering system may significantly reduce airborne levels of some irritant such as tobacco smoke particulates, they do not significantly affect levels of dust mite allergens (which exist mainly in a settled state on bedding, overstuffed chairs and floor coverings) and probably have little effect reducing levels of animal dander allergens. (See Tovey review and our review of article by Wood et al in the Current Lit section).

  7. The value of HEPA-filter equipped vacuum cleaners is somewhat controversial. As pointed out by Platts-Mills, an expert in avoidance measures, the effectiveness of vacuum cleaners depends on how tightly sealed the unit is.

  8. Having said all that, I am not aware of any differences in the "allergenic potential" of houses constructed primarily of wood vs. brick, as questioned by you. There is little if any tree allergen present in the wood used in house construction. For awhile, there has been concerns raised in certain quarters about possible release of potentially sensitizing formaldehyde from certain types of insulation blown into the spaces behind drywalls.

 
5/19/00 re: Does mattress encasing and carpet removal really help asthma
Q. I am a dermatologist/allergologist in Germany. I read that encasing bed furniture does not really prevent or diminish development of asthma. An evidence based report could not found any proof of benefit by expensive encasing furniture. Similarly carpet cannot be excluded automatically because it also has positive effect of "holding" the dust. Thus the Allergy Clinic did put in carpets in all its bedroom for patients. What do you think about it? A social assurance in Germany (AOK) asked me - what was the newest scientific knowledge about  this problem. I asked 2 clinique heads and got 2 opposite answers in Germany.
A. You are correct that there are some differences of opinion in this area. First one has to ask several questions about individual asthma cases.
  1. Is prominent dust mite sensitivity present, as documented by strong prick test reactivity?

  2. Are there allergies to other aeroallergens present in the patient's environment (animal danders, roaches, etc.), irritants such as tobacco smoke. If these other factors are not controlled, the beneficial effects of dust mite avoidance may not be observed.

  3. Is the patient's environment humid (>40% relative humidity). Dust mite growth is markedly increased in humid environments making significant reduction in mite allergen levels much more difficult.

Once these questions are dealt with, one can look at the available evidence in the literature. I think that you may be referring to a metanalysis (reviewed by me for this AADMC web site - enclosed below) which concluded that dust mite control measures were not really that helpful. As you can see in my review, the methodology in this metanalysis was criticized by Dr. Platts-Mills, one of the leading investigators of dust mite sensitivity. Perhaps, one of the most balanced recent reviews of this subject by Tovey et al (see my review of that article enclosed  below. I suggest that you read the whole article).

A final comment concerns your remark that carpeting may be actually beneficial by trapping airborne dust mite allergenic particles. Actually, such mite allergens normally do not remain suspended in the air for long periods of time. They settle out in surfaces where they are encountered by humans. They are also inhaled after being temporarily suspended from such surfaces into the surrounding air due to air currents and other mechanical factors (see enclosed review by me).

Are mite avoidance measures worthwhile in dust mite allergies?

SUMMARY
Mite avoidance measures have been advocated by many experts in cases where mite-sensitive individuals have related symptoms in the upper and/or lower airways. Burr et al of the University of Wales College of Medicine carried out a meta-analysis of randomized, placebo-controlled trials of the effects of physical and/or chemical measures to reduce dust mite allergen concentration in the home on clinical manifestations in mite-sensitive asthmatics. Only 18 of the many studies reviewed met the inclusion criteria of the authors. Another 4 studies were "retrieved by Dr. Burr's personal archive." He concluded that there was no significant improvement in the asthma following mite control measures.

Dr. Thomas Platts-Mills of the University of Virginia School of Medicine strongly rebutted Dr. Burr's conclusion. He pointed out that demonstrated beneficial effects in some of the reviewed studies were "diluted" by results in other studies where ineffective or inadequate measures were used in an attempt to control mite allergen concentrations.

REFERENCE - BMJ 1998;317:1105-1110

EDITOR'S COMMENTS
Although Dr. Platts-Mills can be considered a strong, vocal advocate of mite control/avoidance approaches for mite-sensitive individuals with asthma, I think that he has made an important, valid point. There has been a considerable change and evolution in mite control measures in the past 10 years. Therefore, one should include careful analysis of clinical effects for only those studies where reduction in mite allergen concentrations have been convincingly shown.

 

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 >130¦ 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!

 

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 (>120° 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;104:499-500

EDITOR'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.

Allergen avoidance - what really works?

SUMMARY
There has been continued great interest and investigation of allergen avoidance approaches, particularly related to the hope for reducing the increasing frequency of asthma noted in recent years. Squillace of the University of Virginia Medical Center has briefly reviewed the efficacy of different approaches described. She first cited evidence that the asthma of mite-sensitive people definitely improved when moved into mite-free environment. Effective measures to reduce home mite levels to levels below that though to trigger asthma include: 1) use of impermeable covers on mattresses and box springs; 2) weekly hot water washing of bedding and 3) removal of carpets. However, air filters, special vacuum cleaners, chemicals to treat carpets and upholstered fabrics and cleaning of heating/cooling ducts have not proven to be sufficiently effective. Cockroach allergen plays a major role in the asthma of inner city children. Although roach allergen eradication is quite difficult, extermination, then thorough cleaning (particularly in the kitchen area) and eradication of roach access to food and water are helpful.

REFERENCE - J Respir Dis 1999;20:13-16

EDITOR'S COMMENTS
The author of this review has participated with her colleague Dr. T. Platts-Mills in some of the most important studies of the effects of indoor allergen in the pathogenesis of allergic rhinitis and asthma. Her impressions described above are generally shared by Drs. Wood and Eggleston of Johns Hopkins, other major investigators in this area. Wood et al have also recently reported that HEPA filter units do not reduce airborne cat allergen levels (in cat containing homes) below that causing asthma. (See review in this Current Literature section). HEPA filter equipped vacuum cleaners with heavy duty motors and tight sealing may reduce allergen levels but often not enough to reduce asthma risk.

However, some investigators in Australia are more optimistic about the clinical effects following use of chemicals which either kill dust mites or denature the mite allergens. However, such chemical treatments only transiently reduce allergen levels and frequently require re-application every 3-6 months, particularly in humid environments. In that regard, reducing the relative humidity below 50% has been shown to significantly reduce mite proliferation.

 

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;101:451-56

EDITOR'S COMMENTS
This report emphasizes what is becoming generally agreed. Even when shampoos or other applications do reduce mite numbers or 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.

 
3/27/00 re: Avoidance of horse hair in walls
Q. I am a school nurse in an elementary school and have a nine year old student who is asthmatic. She has tested positive for many allergens, one of which is horse hair. She lives in an old house (100 yrs approx.) with plaster walls. There is a good chance horse hair was used in the walls. Question: Is there any effective action the parents can take, short of moving, to reduce their daughter's exposure to the horse hair? In other words, have you found that covering the walls with paneling, or some other action, has proven to be effective?
A. From your description, I think that this child, sensitive to multiple aeroallergens, faces many problems living in this very old house (molds, mites, roaches), not just the possibility that there may be horse hair in the wall coverings. But first, one must establish that the child's respiratory problems are definitely worse while living in the home. The simplest approach is a trial of living with a relative who lives in a relatively new home in the same geographic region. If careful observation over a period of weeks shows definite decrease in symptoms during such a trial, followed by increased symptoms after moving back into the 100 year old house, a convincing argument can be made of a permanent move. If such a move is not feasible, extensive renovation of the old house may be necessary, particularly if it has a "musty" odor. Such renovation could include covering the walls with tightly fitting fiber board or paneling if indicated.

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