Doctors and scientists have known about the dangers of house dust mites for quite some time, but this information does not tend to get out to the public. So we hope that this timeline helps you understand the importance of avoiding mites, instead of just relying on your medication! We think its important that this sort of research is available to the people who suffer with allergies and asthma.
As early as 1694, scientists were observing mites in house dust. By 1923 doctors knew that they were involved in causing occupational asthma. However, it wasn't until 1967 that confirmation came that they were a major source of allergens in house dust. Five years were to pass before doctors identified the droppings, not the mite, as the cause of allergy problems.
'The house dust mite Dermatophagoides pteronyssinus and the allergens it produces identify with the house dust allergens', Voorhorst R, Spieksman I.Th.M., Varekamp H, Leupen MJ & Lyklema A W, 1967, J. Allergy, 39, pages 325 to 339
An early allergy treatment of using a series of injections designed to stimulate the body's immune system against mite allergy is explored by scientists.
'Treatment of house dust allergy with pyridine extracted alum precipitated mite fortified house dust', (Allpyral), Munro-Ashman D, Frankland AW, Brown HM, Langman MJS, Ann. Allergy 1971, 29 (Nov); pages 578 to 581
Doctors, working with children diagnosed with allergic asthma, recognise that house dust mites are a major contributor to the disease. The doctors try to lessen the children's symptoms by using a series of injections (immunotherapy) against mite allergy.
'Controlled Trial of Hyposensitisation to Dermatophagoides pteronyssinus in Children with Asthma',1978, Warner JO, Price JF, Soothill JF, Hey EN, October 28th 1978, The Lancet, p 912
Doctors found that by reducing house dust mites in patient's bedrooms, health improvements can be noted. Their findings, 1983 and 1986, were published in medical journals for reference.
'Dust free bedroom in the treatment of asthmatic children with house dust mite allergy; a controlled trial', Murray AB, Fergusson AC, Pediatrics, 1983; 91, pages 418 to 422
'Allergen avoidance in house dust mite sensitive adults with asthma' Walshaw MJ, Evans CC, Q.J. Med. 1986; 58, pages 119 to 215
Medical opinion leaders met to describe the mite Dermatophagoides pteronyssinus as a major cause of allergic asthma, rhinitis (hayfever) and eczema. In order to reduce the burden of these allergic diseases on society, the doctors called for urgent research to find ways to reduce mite infestations and exposure. They also identified the practical (proven) methods to accomplish this task.
'Dust Mite Allergies and Asthma - A worldwide Problem', Platts Mills TAE, de Weck A, UCB Institute of Allergy, Bad Kreuznach September 1987. Reported in The Journal of Allergy and Clinical Immunology, 1989, 83, pages 416 to 427
The major house dust mite allergen, is identified as an active enzyme with properties similar to papain. Papain is commonly used in food manufacturing as a meat tenderizer.
'Sequence Analysis of cDNA coding for a major house dust mite allergen Der p1', Chua K.Y. et al, J.Exp. Med.; Vol. 167 Jan 1988, p175-182
UK scientists, investigating house dust mites as a cause of childhood asthma, identify a link between mite exposure in beds, asthma and a specific gene (chromosome 11q).
'Exposure to house dust mite allergen (Der p1) and the development of asthma in childhood, a prospective study', Sporik RS, Holgate ST, Platts-Mills TAE,
Cogswell, JJ, 1990 New England Journal of Medicine, Vol. 323, pages 502 to 507 'House dust mite sensitivity: interaction of genetics and allergen dosage',Young RP ,Hart BJ, Merrett TG, Read AF, Hopkin JM, Clinical and Experimental Allergy, 1992: Vol.22, pages 205 to 211
Doctors are so concerned that active mite enzymes can breach lung defenses by attacking vulnerable tissue that they write and submit a letter to a medical journal stating their concerns.
'Effect of mite allergen on permeability of bronchial mucosa', Herbert CA, Holgate ST, Robinson C, Thompson PJ, Stewart GA, The Lancet, November 3rd 1990, page 1132
A clinical study reports that symptoms of mite related childhood asthma are improved by active allergen avoidance. The report, plus a medical publication written at the same time by nine opinion leaders in asthma, support allergen avoidance in the management of allergic disease.
'Reducing domestic exposure to dust mite allergen reduces bronchial hyperreactivity in sensitive children with asthma'. Ehnert B, Lau-Schadendorf S, Weber A, Buettner P, Schou C, Wahn U.; J.Allergy Clin.Immunol. 1992, 90, pages 135 to 138
'The control of allergens of dust mites and domestic pets: a position paper',
Colloff MJ, Ayres J, Howarth PH, Merrett, Mitchell EB, Walshaw MJ, Warner JO,
Warner JO, Woodcock AA, Clinical and Experimental Allergy, 1992 Vol. 22, Supp.2, pages 1 to 28
Publication of the revised British Thoracic Society Guidelines for the Management of Asthma did not specifically support mite avoidance in asthma management but called for new or improved drugs to control symptoms. The guidlines, and thier recommendations, were not revised and published until 1997.
Thorax 1993; 48, Supplement S1 to S24 and The British Medical Journal, 20th March 1993, Volume 306, page 776 to 782
A paper reviewing all current evidence on domestic mites and their role in allergy is published. The paper is significant in understanding the biology and ecology of allergenic mites. It also gives clear indications on how to control their numbers indoors. In the same year, a team of UK doctors first describe evidence of cell damage caused by mite enzymes. Damage which increases immune reactions in allergy.
A Major House Dust Mite Allergen Disrupts the Immunoglobulin E Network by Selectively Cleaving CD23: Innate Protection by Antiproteases', Hewitt CRA, Brown AP, Hart BJ, Pritchard DI; J.Exp.Med; 1995, 182, p1537-1544
A scientific report on how enzymes found in house dust mite droppings can cause 'allergic-like' symptoms before true (specific IgE) allergy develops. The possibility of a vaccine is considered as a remedy.
'Potential allergens stimulate the release of mediators of the allergic response from cells of mast cell lineage in the absence of sensitisation with antigen-specific IgE' Machado DC, Horton D, Peachell P T, Helm B A, Eur J. Immunol. 1996, 26, 2972-80
Newly revised British Thoracic Society Guidelines for the Management of Asthma are published and distributed. The guidelines offer some support for mite avoidance, but report that mite reduction is very difficult to achieve and benefits remain to be proven effective.
Revised from 1992, The BTS Guidelines for the Management of Asthma, Thorax; Feb. 1997 Vol. 52, Supplement 1, page 54
Scientists describe how four house dust mite enzymes (working together or separately) can cause and trigger allergic reactions. This paper confirms that elements found in mite droppings can actually breach lung defenses by permeating tissue to raise alarm in the immune system.
'Environmental risk factors in atopic asthma'. Koren HS; Int.Arch.Aller.and Immunol.;1997, Vol. 113: 65-68
'Mite allergens: significance of enzymatic activity', Hewittt CRA et al., Allergy; 1998, Vol. 53, Supplement 48, p60-63
An analysis of all randomized clinical trials (1980 -1996) on mite avoidance in asthma found that all previous attempts had failed to prove efficacy because of poor study designs.The authors of the analysis called for new and improved studies and asked researchers not to repeat failed study designs, as they were unlikely to succeed. In describing the failed attempts, the analysis noted, single intervention studies, and studies that were successful but too small in patient numbers to be considered significant.
House dust mite control measures in the management of asthma: meta-analysis.
Gotsche PC, Hammarquist C, Burr M., British Medical Journal, 1998;317:1105-1110
A dose-response relationship between house dust mite allergen exposure and specific sensitization in infants and children is confirmed and subsequent allergen exposure in sensitized people with asthma increases the severity of the disease. In the UK alone, 85% of asthmatic children are allergic to house dust mites.
'Early exposure to house dust mite and cat allergens and development of childhood asthma', a cohort study', S.Lau et al, The Lancet, Vol. 356, pages 1392 to 1397
Researchers, investigating the home environment of families with infants 'at risk' of developing asthma, successfully reduced indoor mite colonies to achieve and maintain very low allergen levels. The practical and cost-effective techniques applied included, 1. Removal of carpets in bedrooms 2. Covering all beds and bedding with micro-porous mite resistant material 3. Using high-filtration vacuum cleaners to control dust 4. Use of mite killing sprays on soft furnishings 5. Installing high efficiency dehumidifiers in bedrooms. With this ground-breaking achievement doctors also noted health improvements and lower reliance upon medication for asthma.
The study investigating 'at risk' infants and mite allergen avoidance began in 1995 and is on-going in 2004.
'Manchester Asthma and Allergy Study: Low-allergen environment can be achieved and maintained during pregnancy and in early life', Custovic A et al, 2000, J. Clin. Immunol. 105, No.2, Part 1, pages 252 to 258.
Dr Jill Warner, 1996, January 28th 'The Pulse', Channel 4 Television Production, University of Southhampton UK.
Dr Jill Warner, 1998, June 17th, 'Asthma', Channel 4 Television Production, University of Southhampton UK.
A paper is published reporting that mite allergens have been identified in the fetal fluid and circulation of newly born infants.
'Detection of House Dust Mite allergen in amniotic fluid and umbilical-cord blood'; Holloway J A, Warner J O, Vance G H S, Diaper N D, Warner J A, Jones C A ,The Lancet, 2000, Issue 9245, 1900-1902.
By controlling indoor humidity (below 51% relative humidity), house dust mite populations were reduced by 76.5%. The seventeen-month study took place in a temperate climate that included two humid summers. Researchers used free-standing high efficiency dehumidifiers and air-conditioning as the only physical intervention.
'Reducing relative humidity is a practical way to control dust mites and their allergens in homes in temperate climates'. Arlian LG et al, 2001, J. Allergy Clinical Immunol. Volume 107, number 1, pages 99 to 104
In chronic allergic conjunctivitis doctors recommend testing for a specific allergy to house dust mites because the mite's allergen can cross the mucus membrane that covers the eye to cause an allergic reaction.
'Management of seasonal allergic conjunctivitis (SAC): current therapeutic strategies', D F Anderson, Clinical and Experimental Allergy, 2001, Volume 31, pages 823-826
Top UK scientists describe (for the first time) how an aggressive allergen found in mite droppings (Der p1) can reduce the efficiency of lung defenses. The doctors speculate that this may be the reason why asthmatics suffer more lung infections than healthy people.
'House Dust Mite Der p 1 Downgrades Defenses of the Lung by Inactivating Elastase Inhibitors', Brown A, et al,Am.J.Respir.Cell Mol. Biol. 2003 Vol 29;pages 381 to 389
Atopic dermatitis (AD) is a common skin disease of dogs and is estimated to affect 3 to 30% of the dog population. House dust mites are reported to be among the most common allergens that cause hypersensitivity in dogs with AD (affecting 30 to 100% of dogs diagnosed with AD).
'Quantitiation of house dust mites and house dust mite allergens in the microenvironment of dogs' Randall A, Hillier A, Cole LK, Kwochka KW, Needham G, Wassom DL, AJVR 2003 Vol 64:No.12;1580-1588
Newly formed guidelines for the management of asthma state that allergen avoidance is still not proven to prevent or control the symptoms of allergic asthma. Larger and more carefully controlled studies are required to demonstrate any clear benefit from house dust mite avoidance. At present this does not appear to be a cost-effective method of achieving benefit.
British Thoracic Society (BTS) and SIGN, 2003, Guideline No. 101. ISBN 978 1 90581 28 5. Updated 2008
Reports from Asthma UK and The Royal College of Physicians state that allergy and allergic diseases have reached epidemic proportions and that the National Health Service is not coping with demand for healthcare to treat symptoms. They also report that children bear-the-brunt of allergic asthma, rhinitis (hay fever) and eczema. The doctors report in unison, 'house dust mites are a potent cause of allergy. Once allergy is established it is important to reduce exposure'.
Allergy, the Unmet Need, Royal College of Physicians' Report, June 2003, .ISBN 1 86016 183 9
'Controlling indoor allergens'. Warner JA, Pediatr. Allergy Immunol. 2000: Volume 11; page 208-219
Doctors believe that exposure to indoor allergens, particularly increased airborne fungal spores, are important in the development of adult asthma and is blamed for an increased tendency to 'be allergic'. Previously, it was thought that allergen exposure was only important in the development of asthma in children, however doctors warn that increased exposure to 'Alternaria' and 'Cladosporium' can be responsible for more severe adult asthma. Admissions to hospitals' Intensive Care Units and some cases of respiratory arrest have been identifed as mould-related. House dust mite and cat allergens were also implicated in new adult asthma cases. In the interest of public health, calls are made for urgent allergen control and avoidance in the indoor environment. Questions on the importance of 'classical' allergy (IgE) markers, as displayed in skin prick or blood tests, remain to be resolved in adult asthma. There appears to be another allergy marker, a relative of IgE, referred to as IgG, that may also be involved.
Changes in indoor allergen and fungal levels predict changes in asthma activity among young adults, Matheson M.C. et al, 'Clinical and Experimental Allergy'; Vol. 35: pages 907-913
A review of recently published clinical studies on the effectiveness of allergen avoidance in the management of childhood asthma, reported that encasement of beds and bedding against house dust mite exposure resulted in sustained and meaningful health improvements. The doctors also noted that other avoidance measures geared to the child's allergies, combined with the exclusion of tobacco smoke indoors, resulted in significant reduction of symptoms and hospital emergency room visits.
'The role of allergen avoidance in the secondary prevention of atopic disorders.' Simpson A and Custovic A, Current Opinion in Allergy and Clinical Immunology.2005, 5 (3): 223-227
Little is known of the fate of inhaled house dust mite allergens once they enter the body via the lungs. By tagging the allergen with a novel gamma-emitting tetrapeptide, progress has been monitored in laboratory mice manipulated to be allergic to the study allergen. The lungs of the sensitized mice retained the allergen in the lungs twice as long as the healthy control mice. Radioactivity was found in the enlarged lymph nodes associated with the lungs, the kidney and the liver of the mice. Based upon the findings the research team concluded that the inflammatory rate of the lungs influenced the clearance of the allergen, thus an allergic response to the allergen may lead to prolonged retention in the lung.
'A mouse model for in-vivo tracking of the major dust mite allergen Der p 2 after inhalation'. Johansson L, et al, FEBS Journal,2005;272(13):3449-3460
Recommendations on how to encourage a balanced immune response to reduce the rising incidence of asthma: 1. Develop a healthy gut flora primed to counter bacterial infection; 2. Live in a low allergen home, school, or office; 3 Take regular outdoor exercise with less time indoors for inactive pursuits; 4. Have a healthy and balanced diet.
'Environmental Factors Influencing Allergy and Asthma', Platts-Mills TAE, Erwin EA, Woodfolk JA, Heymann PW, The Environment, Allergy and Asthma in Modern Society: A Scientific Approach. 'Chem. Immunol. Allergy', Basel, Karger, 2006. Vol. 91, pp 3-15
The risk of developing serious eye disease during the pollen season is increased by continuous exposure to year-round allergens that cause asthma, chronic hay fever, eczema and conjunctivitis. Allergen avoidance is strongly recommended to reduce the risk. Avoidance of aggressive allergens, such as from mite enzymes, is noted in this excellent paper.
The eye is probably the most common site for development of allergic-inflammation because eye irritants, including allergens, are easily deposited directly onto the surface of the eye. Other than the release of repellent mediators such as histamine (making the eye red, sore or itchy) the eye has no mechanical barrier to prevent the impact that allergens create. To make matters worse, tears themselves, bearing allergens absorbed from other parts of the body, may carry them onto the eye. During the pollen season therefore it is important for patients who suffer from pollen allergies and allergic disorders such as chronic hay fever, eczema or asthma, to be diligent in practicing allergen avoidance.
Aggressive enzymes from house dust mites are a major cause of allergy worldwide. In the United States of America alone, the prevalence of allergies ranges from as high as 30% to 50% of the population.
Website note: cross-reactivity in allergy is common. If you are allergic to grass pollen it may be wise to avoid eating wheat during the grass pollen season because wheat is a cultivated grass and your immune system may recognize the similarity.
'Allergic Diseases of the Eye', Dr. Leonard Bielory, The Medical Clinics of North America, 90 (2006): pages 129-148
Dogs can be strongly allergic to house dust mites too, but the allergens that cause dermatitis in dogs are different from the major mite allergens that affect humans.
Dogs react to enzymes that act to degrade chitin. Chitin comes from the outer part of insects and from the cell walls of fungi. For mites, both dead insects and fungi are an important part of their diet, as they need to break down chitin to get nourishment. Scientists have named the guilty allergens as Der f 15 and Der f 18. These allergens are from the American house dust mite 'Dermatophagoides farinae', a mite that is now found worldwide. To safeguard your dog against mite-related dermatitis, keep your dog's resting place mite free and wash your dog regularly with a shampoo that contains a small amount of tea tree oil.* The oil will act to clog up the breathing holes on the mite's shell. This will suffocate the mite. *Please refer to your vet before taking this action.
The chitinase allergens Der p 15 and Der p18 from Dermatophagoides pteronyssinus. O'Neil SE, Heinrich TK, Hales BJ, Hazell LA, Holt DC, Fischer K, Thomas WR, Clinical and Experimental Allergy, 2006, 36, 331-339
'The Non-catalytic Chitin-binding Protein CBP21 from Serratia marcescens is Essential for Chitin Degradation', Vaaje-Kolstad G et al, J. Biological Chemistry,280, (31) p.28429-28497
Based upon research describing the immunobiological profiles and potential allergenicity of antigens from house dust mites* this paper demonstrates how major and mid-range mite antigens can trigger a wide range of antibodies in the human immune response.
The responses range from excessive immediate IgE allergic reactions associated with acute childhood asthma to IgG4 allergic responses in adults and children.
'IgE and IgG antihouse dust mite specificities in allergic disease' Hales BJ, Martin AC, Pearce LJ, Laing IA, Hayden CM, Goldblatt J, Le Souef PN, Thomas WR. 2002 J Allergy and Clinical Immunology, 22 May online. (in press) doi:10.1016/j.jaci.2006.04.001
*Characterization and Immunobiology of House Dust Mite Allergens, Thomas WR, Smith WA, Hales BJ, Mills KL, O'Brien RM, Int Arch Allergy Immunol, 2002, 129:1-18
The mite allergen 'chitinase' is an enzyme that degrades chitin. Chitin, a linear polymer, comes from the outer layer or exoskeleton of all arthropods and from the cell walls of fungi.
Both dead insects and fungi are an important part of the mite's extensive diet. The enzyme that degrade chitin can also be found as 'helpful tools' for pathogenic micro-organisms such as the malaria parasite Plasmodium falciparum. Chitinase expressed by this parasite helps it to break out of its mosquito host.*
Little is known of the impact that the 20, or so, mite allergens have on the health of mammals. Traditionally research has focussed on one or two of them (Der p1 and Der p2) consequently they are well described scientifically but researchers have failed to take a 'snap-shot' of the total impact all mite allergens have on health. Doctors are now addressing this problem in the interest of science and for the improvement in treating mite allergic patients or those considered at risk from mite related disease. By taking a selection of 9 house dust mite allergens (major and minor) and analyzing, first their individual, and then combined, allegenicity in concert, a truer picture of the impact that mites have on human health will emerge. In future this knowledge can be applied both in research and in helping patients to receive precise individual immunotherapy treatment. The doctors also address a confounding feature; that major house dust mite allergens Der p1 and Der p2 can change depending upon the mite's habitat world-wide.
'Determinants of House Dust Mite Allergenicity', Hales BJ, Nora NR Chu, Bosco A, Smith W-A,Tatjana KH, Thomas W R, Allergy Clin.Immunol.Int. and J.World Allergy Org, 18/2 (2006) 'Research Trends', pp 65-70
A detailed scientific description of the pathway from mite exposure to allergy
Within the text of the book there is an excellent review of the activities of the major house dust mite allergen Der p1. This review is headed: 'Proteases Are Major Allergens derived from Various Organisms', page 48 to 52. The chapter clearly describes the destructive pathways of which Der p1 is capable. As an active digestive enzyme it can even mimic a parasitic invasion by 'clipping off' sensors of delicate immune cells. The chapter also describes how Der p1 can cause non-IgE reactions, which then can cascade towards allergy and asthma.
The book also addresses how it has recently been demonstrated that helminth (worm) infections have negative effects on allergic disease manifestation. Scientists now believe that regulatory cell populations appear to control Th1 and Th2 immune responses. Regulatory cells such as T and B cells, natural killer T cells, mast cells and basophiles, all come under the scrutiny of the international teams that contribute to this work. Many of these cells also respond to parasites and house dust mite droppings.
This is important reading for students wishing to study how house dust mites affect human health.
'Parasites and Allergy'
Chemical Immunology and Allergy, Vol.90
Editors M. Capron; F. Trottein, Lille
2006, ISBN 3-8055-7974-8
A thirty-five year review of skin tests confirms that they remain the central tool in allergic response.
Analysis of the value to allergists of skin testing from papers published between 1970 and 2005 concludes that; when preformed and evaluated correctly, skin testing is the most effective diagnostic tool available for the confirmation of allergic disease. The test, however must be combined with a physical exam and notations of the patient's medical history and social environment in order to give a sound basis for managing allergies and allergic disease.
The paper includes a clinical form and stepped procedure for clinical technicians on how best to record and evaluate skin tests. As house dust mites are known to be the major cause of allergy, worldwide, and the environment in which they thrive encourages moulds, and other allergy triggers, early skin prick testing, especially for children, is recommended.
John Oppenheirmer MD, Harold S Nelson MD
Ann Allergy Asthma Immunol. 2006;96 (Suppl.1): S6-S1
Scientists found that, by first creating and then refolding a crystallized structure of a major mite allergen Der f1, they could manipulate the human immune response from a Th2 to Th1; that is, from the allergic to non-allergic immune signalling. This alteration in the folding of Der f1 took place without changing the allergen's amino acid sequence This ground breaking research may lead to novel drug strategies in treating patients with allergic disease caused by exposure to the house dust mite Dermatophagoides farinae.
'Crystal structure and some properties of a major house dust mite allergen, Der f2' Masashi Suzuki, Yoshimasa Tanaka, Seigo Korematsu, Bunzo Mikami, Nagahiro Minato. Biochemical and Biophysical Research Communication 339, (2006) 679-686.
Genes plus environmental factors can affect the developing structure of foetal airways before sensitisation to known allergens. Two basic components contribute to asthma; altered airway wall structure and airway inflammation. This paper argues that genetic polymorphism plus environmental factors can influence foetal airway wall structure independent of allergic sensitisation and that this phenomena can take place simultaneously leading, but not inevitably, to allergy and asthma.
The paper is also a review of clinical studies on allergen/antigen exposure in early life including discussion on the gene encoded SPINK5 which protects epithelial cells against the major mite allergen. It also discusses the effect of nutritional influences on lung function, how neutrophiles, as opposed to eosinophiles, can impact on airway remodelling and how postnatal infections and pollutants promote inflammatory immune response not associated with allergy but with transient infant wheeze.
'Developmental Origins of Asthma and Related Allergic Disorders', J.O. Warner 2006, Chapter 26, p 349-369; Developmental Origins of Health and Disease, Published by Cambridge University Press. Edited by P Gluckman, M Hanson
Recurring airway inflammation in sensitised children before the age of 3 is predictive of chronic asthma and impairment of lung function at school age. House dust mite, dog and cat allergens are implicated in this process.
This study followed 1314 children from birth to 13 years of age. The children were regularly checked and tested for allergic response and allergen exposure. 90% of the study children with wheeze, but no atopy, lost their symptoms at school age and retained normal lung function. By contrast, study children sensitised to perennial inhaled allergens before the age of 3 were found to be associated with significant loss of lung function at school age. High exposure to inhaled allergen in these vulnerable children enhanced airway hyper-responsiveness and reduced lung function. Common inhaled allergens were from house dust mites, dog and cats.
In conclusion the paper raises an important issue: 'Given the good prognosis for non-atopic wheezing children, the need for these individuals to continue to take inhaled corticosteroids on a regular basis should be re-assessed.' Estimated cost of treating EU children with asthma is 3000 million Euros per annum.
'Perennial allergen sensitisation early in life and chronic asthma in children: a birth cohort study', Sabina Illi, Erika von Mutius, Susanne Lau, Bodo Niggeman, Christoph Gruber, Ulrich Wahn, on behalf of the Multicentre Allergy Study (MAS)group, Lancet, 2006, Vol. 368, p 763-770
Asthmatics suffer longer bouts of respiratory infections because of an inappropriate response in deleting infected cells. Respiratory viral infections are associated with the majority of acute exacerbation of asthma, and of those approximately 60% are from human rhinoviruses (RVs). Adults with asthma have been shown to have an increase in severity and duration of naturally occurring viral infections, especially RV-16. The reasons for this are now becoming clear. There appears to be a defective innate immune response (IFN-b) in the asthmatic lung that causes chaos. Instead of infected cells 'self-destructing' and being 'swept' away as a normal defence mechanism, the asthmatic lung reacts slowly letting the infected cell die from the activity of the virus. This action sets off pro-inflammatory immune responses, which exacerbate asthma, and also release progeny viruses, which then infects neighbouring cells.
For people with allergic asthma it is important that chronically inflamed airways (asthma) are kept to a minimum. Allergen recognition and avoidance plus properly prescribed medication are vital in health protection.
'Innate Immunity in the Pathogenesis of Virus-induced Asthma Exacerbations', Sebastian L. Johnston, The Proceedings of the American Thoracic Society, 2007, 4:267-270
Woven materials designed for allergen avoidance prove to be more effective in reducing mite and cat allergens than non-woven fabric. Tests were carried out on two separate classes of materials clinically proven to exclude mite and cat allergens from mattresses. One was a woven fabric with a pore size of 6mm (6 millionths of a metre) the other was non-woven, short length filament, compressed fabric similar to felt. The aim of the study was to investigate and compare the allergen/dust levels on the surface of the two materials (20 non-woven and 12 woven) after one year of constant usage. An observation made during this study was that although the non-woven fabric is tight enough to block the passage of allergen, the depth of the fabric can offer mites hiding places for mites with the potential for colonisation. This was not observed in the woven material.
Higher levels of allergen were found on the rough surface of the non-woven material. Concern was expressed that on this material allergens could actually be pushed into the substrate during clean wiping or act as a 'sink' for loose allergens. In this paper, given the fact that higher levels of both cat and mite allergens were found on the surface of the non-woven material, questions were asked about the validity of claims of allergen avoidance for this product.
'Nonwoven, in contrast to woven mattress encasings accumulate mite and cat allergens', Letters to the Editor, Miller J d, Naccara L, Satinover, S, Platts-Mills TAE, J Allergy Clin Immunol. 2007, Vol. 120, Number 4, p 977-979
Significant increase in house dust mite sensitisation and allergy has been recorded in the general population of a city with low and stable levels of air pollution.
The health of selected subjects, originally enrolled in a cross sectional study on allergen sensitization in 1984, were revisited and reviewed in 1998. They came from the wide age range of 14 to 64 and all were living in a city with a low and stable level of air pollution. The researchers found a significant increase in sensitization and allergic symptoms to common indoor allergens, especially the house dust mite for all age groups and that this increase is best seen in subjects with conjunctivitis and rhinitis rather than with symptoms of asthma. This report also reviews other large population studies, many of which agree with this study's findings.
'Skin prick-test reactivity to aeroallergens and allergic symptoms in an urban population of central Italy: a longitudinal study', Dottorini ML et al, Clinical and Experimental Allergy, 2007: 37; 188-196
Year round allergic rhinitis, caused by allergens, including mite allergens and animal dander, may not only affect quality of life but also mental performance.
Allergic rhinitis is extremely common. It is one of the top ten reasons for visits in primary care clinics in Europe and the USA. House dust mites and animal dander allergens are the most frequent cause of perennial symptoms. It may be difficult to differentiate between seasonal allergic rhinitis, caused by a wide variety of pollens, and perennial allergic rhinitis because most patients are polysensitised.
Allergic responses are termed early and late phased symptoms. An early response occurs within minutes of exposure with symptoms that may include sneezing, itching and a clear runny nose. Late phase response 4 to 8 hours after exposure may be less well recognised. It may be characterised by fatigue, malaise, irritability, and possibly neurocognitive defects.*
In this short paper classifications of symptoms from intermittent to severe are described.
'Introduction', Allergy, 2007: 62 (Supp. 85): p.3-5 Scadding G.K., Bousquet J. [cross sectional international survey on allergic rhinitis]
*'Allergic rhinitis: definition epidemiology, pathphysiology, detection and diagnosis', Skoner DP; J. Allergy Clin. Immunol. 2001: 108; S2-S8
Inner city children with asthma demonstrated clinical benefits through an individualized allergen recognition and avoidance programme. In a large clinical study in seven U.S. cities, 937 asthmatic children (age 5 to 11) were individually clinically tested for allergy triggers and exposure to tobacco smoke. The study then evaluated the effectiveness of multifaceted, home based, environmental interventions designed to improve individual morbidity and decrease their use of health care services. Common allergens detected were from cockroach, cat, mould and house dust mites. The goal of the study was the modification of behavioural change through interventions and education. Interventions included, allergen-impermeable covers on mattress and pillows to reduce mite exposure, vacuum cleaners with a HEPA filter or bare-floor brush for cleaning hard floors, professional pest control visits if cockroach was discovered. In addition, if passive smoke, mould, dog or cat allergens were identified as triggers, a HEPA air purifier was installed in the child's bedroom.
The study demonstrated sustained reductions in indoor allergen levels and sustained improvements in reported asthma morbidity. A year-long study with one year follow-up.
'Results of a Home-Based Environmental Intervention among Urban Children with Asthma', Morgan W J et al, 2004: 351: p 1068-80, New England Journal of Medicine
Mite allergic patients, exposed to a bacterial antigen, can, in tandem produce antigen/allergen specific IgG4, an antibody associated with anaphylactic reactions.
This study investigates how some mite allergic adults and children, exposed to H influenzae endotoxins, in tandem can produce antigen or allergen-specific IgG4, an antibody associated with anaphylactic reactions. The study raises questions on the possibility of antigen/allergen interactions and asks if this interaction can encourage the development of asthma and allergy in early life. In adults the reaction may prolong symptoms of asthma or rhinitis following a respiratory infection or a heavy cold. A quote from the study: 'H influenzae endotoxin can directly trigger the release of inflammatory mediators from basophils and eosinophils, and there is evidence from the release of eosinophil cationic protein that they do this in the lungs. 'Infants can make IgG4 antibody as shown in food allergy and responses to vaccines and virus infections.' Once triggered, either by mite allergens or bacterial endotoxins, basophils in the blood and mast cells in the lung can release histamine, elastase and tryptase, some of the many pro-inflammatory markers in respiratory disease.
This study may be important in the research of cot deaths caused by the possibility of modified-anaphylaxis due to production of IgG4. To explore this further please refer to: 'Sudden Infant Death Syndrome' (Monograph):Coombs RRA, Parish WE, Walls AF, Cambridge Publications (2000)
Differences in the antibody response to a mucosal bacterial antigen between allergic and non-allergic subjects. Hales BJ, Pearce LJ, Kusel MMH, Holt PG, Sly PD, Thomas WR. Thorax 2008; 63: 221-27
'Risk assessment in anaphylaxis: Current and future approaches', Simons et al, J. Allergy Clin. Immunol., 102; 2007: pS2-S24 doi:10.1016/j.aci.2007,05.001
Exposure to house dust mites is a major cause of perennial rhinitis. Steps for treating allergic rhinitis begin with taking the patients clinical history combined with skin prick testing/serum specific IgE blood tests and allergen/irritant avoidance along with nasal douching. If symptoms continue selected medication should be prescribed as listed in the published Guidelines. Allergic rhinitis is predominant among children and accounts for about a third of rhinitis cases in adults. It significantly reduces quality of life and interferes with both attendance and performance at school and work. Allergy to house dust mites or cats is a risk factor for both asthma and rhinitis. Rhinitis is diagnosed by history and examination backed up by specific allergy tests. Standardized allergy education improves disease specific quality of life. Treatment of rhinitis is associated with benefits for asthma. Most asthmatics have rhinitis. Skin prick tests should be carried out routinely in all cases and must be interpreted with a clinical history. This is important as the tests are known to have a high negative predictive value and 15% of patients with positives outcomes do not develop symptoms upon exposure to allergens.
House dust mite avoidance for clinical benefits is most likely achieved with multiple interventions such as mite proofing beds, removing carpets and upholstered furniture.
BSACI* Guidelines for the Management of Allergic and non-Allergic Rhinitis, G.K. Scadding et al; Clinical and Experimental Allergy, 2008, 38, p19-42 (* British Society for Allergy and Clinical Immunology)
A review describing over 20 dust mite allergen extracts, seven of which are active enzymes. It touches on the mite's ecology, biology, allergenicity and allergen cross-reactivity (an example being between mite and shrimp). It is an important and highly recommended paper for students who wish to seriously study domestic mites and why they cause ill health around the world. It is fully referenced for further research.
'Allergens and Allergen Immunotherapy', Fourth Edition, 2008, Chapter 10, Mite Allergens, E Fernandez-Caldas, L Puerta, L Caraballo, R F Lockey; p 161-182; Publisher, Taylor and Francis, 'Clin. Allergy Immuol, 2008; 21: 161-182
Very small particles, such as from diesel exhaust, have been shown to carry allergens deep into the lungs to be deposited in the delicate alveolar region. Studies have shown that alveolar macrophanges (scavenging cells) react to mite allergen by producing nitric oxide, which is a biomarker of inflammation in the lungs. This is a surprising event, because mite droppings are too large in size (10 to 50 microns) to enter the alveoli but instead settle on the bronchi. How the mite's allergen entered the alveolar chamber has yet to be fully described, however, some scientists believe that the allergen seeps though the mite's sealed dropping to contaminate objects nearby.
Nitric oxide production by alveolar macrophanges in response to house dust mite fecal pellets and the mite allergens, Der p1 and Der p2, Peake HL, Currie AJ Steward GA, McWilliam AS, 2008, J Allergy Clinm Immunol, Vol. 112, No 3, 531-537
'Mechanisms of particulate matter toxicity', S Salvi, and S T Holgate Clin. & Exper. Allergy, 1999, Vol. 29 pp1187-1194
ADAM33, was the first novel asthma gene to be identified and cloned in the smooth muscle of the airways. However, if disrupted, it can 'morph' to become a harmful enzyme.
ADAM33 is tightly regulated as a membrane-associated protein that is usually tethered in the mesenchymal cells of the lungs. 'However if activated it can break this 'tether' and change into a rogue enzyme which promotes the increased smooth muscle and new blood capillaries.' The activity of this gene is now thought be be associated with COPD and neutrophil proliferation.' Enzymatic activity from dust mites has been shown to inhibit the natural control of neutrophil elastase. 'Neutrophil elastase is a damaging reactive in lung disorders such as COPD. 'See American Journal of Respiratory Cell and Molecular Biology. Brown A. et al., 2003; Vol. 29: pp. 381-389, 2003
'The soluble form of ADAM33 promotes angiogenesis: implications for airway remodeling in asthma', Holgate ST, Davies DE, Powell RM, Holloway JW: J. Allergy & Clin. Immuno., 2008, 121(6):1400-1406.
Although smoking is associated with COPD, almost half of patients diagnosed with the lung disease have never smoked. Something else is going on. There is speculation that severe and sustained inflammation in the airways of patients with cystic fibrosis and COPD may be due in part to the proteolytic activity of elastase, the cytotoxic moleucules produced by neutrophils in defence of the lungs. In 2003 researchers demonstrated that house dust mite allergen Der p1 can interfere with a natural control that inhibits the harmful effects of elastase, (Am.J. Respir. Cell. Mol. Biol. 2003; 29: 381). Interference of this natural control (elafin) by mite allergen Der p1 may therefore act to amplify neutrophil elastase harm. This paper is an important review of neutrophil elastase and neutrophil elastase inhibitors.
'Neutrophil Elastase (NE) and NE Inhibitors: Canonical and Noncanonical Functions in Lung Chronic Inflammatory Diseases (Cystic Fibrosis and Chronic Obstructive Pulmonary Disease)', Ali Roghanian, Jean-Michel Sallenave, J. Aerosol Medicine & Pulmonary Drug Delivery, 2008, Vol. 21; No. 1: p 125-144.
Glue ear, can be caused by an allergy to house dust mites. Dr Ian Williamson, Senior Lecturer Southampton School of Medicine said that 5-10% of cases are thought to have an allergic basis and advises GPs to use a strategy of 'watchful waiting' for at least one month when managing children with glue ear, as many cases will be spontaneously resolved. During this time, if allergy has been diagnosed within the family, allergy testing for dust mites is advisable.
'Topical intranasal corticosteroids in 4-11 year old children with persistent bilateral otitis media with effusion in primary care: double blind randomised placebo controlled trial', Williamson I. G. et al., BMJ 2009; 339:b4984
www.pulsetoday.co.uk/story.asp?storycode=4124643 by Lilian Anekwe
Dr Colloff has studied the biology and ecology of dust mites for the last 25 years. His book focuses on factors affecting their global distribution, abundance, and allergenicity as well as methods for dust mite control. Drawings, photographs, graphs, and a comprehensive reference section make this 583 page book a must for anyone interested in studying dust mites. Note; Look on page 54 to see fungus hyphae growing out of mite droppings. Mite droppings can be like a 'grow bag' for selected fungi. In another publication Dr Charles E Reed wrote, 'Fungi and mites appear to be the major sources of proteases causing inflammation.' Current Allergy and Asthma Reports, 2007; 7: 368-374
'Dust Mites', Matthew J. Colloff, 2009, CSIRO Publishing, Collingwood, Australia, ISBN 978-0-6430-6589-5
A clinical look at cross-reactivity in mite allergens concludes by recommending diagnostic allergy testing for individual storage mite species as many of their allergens have been found to be species-specific. Storage mite allergen appears not to cross-react with shrimp, even though they share the same common allergen from the shrimp's muscle (Tropomyosin). However, dust mite allergen, Der p10, also a Tropomyosin from the mite's muscle, can significantly cross-react in some people causing severe allergic reactions.
'Cross-reactivity between storage and dust mites and between mites and shrimp', Arlain LG, Morgan MS, Vyszenski-Moher DL, Sharra D., Exp. Appl. Acarols, 2009; 47: p159-172.
This research furthers the investigation into the involvement of one of the 4 protease-activated receptor (PAR2) expressed on airway epithelial cells. PAR2 is known to respond to house dust mite allergen Der p1 and trigger a cascade of cytokine release. Thymic stromal lymphopoietin (TSLP) is produced by epithelia cells and triggers dendritic cell-medicated Th2 type inflammation. The paper demonstrates that TSLP expression is induced in airway epithelial cells by exposure to allergen-derived proteases and that PAR 2 is involved in the process. By promoting TSLP production in the airways, proteases associated allergens may facilitate the development and/or exacerbation of Th2-type airway inflammation, particularly in allergic individuals.
'Proteases Induce Production of Thymic Stromal Lymphopoietin [TSLP] by Airway Epithelial Cells through Protease-Activated Receptor -21 [PAR 2]', Hideake Kouzaki , Scott M. O'Grady, Christopher B Lawrence, Hirohitl Kita. J. Immunol. 2009; 183:1427-1434
A newly discovered cell, named nuocyte, is a key early source of interleukin 13 (IL-13) a crucial immune chemical created during hookworm infestation in the lungs and in the asthma response to triggers such as dust mites. Too much IL-13 can cause lung inflammation by creating excessive nuocytes. Therefore, nuocytes represent a previously missing link in the critical immune pathway that is turned on during asthma attacks. Exposure to either animal can result in an assault on lungs and asthma.
For hookworms the journey into the lungs is an important part of their life cycle. For scavenging dust mites, digestive enzymes found in their droppings cause lung cell death and a breach in defences. For some allergy patients these two pests may be considered equal and unwanted parasites, and react appropriately.
'Nuocytes represent a new innate effector leukocyte that mediates type-2 immunity' Neill DR et a; Nature 464, 1367-1370 (29th April 2010) | doi;10.1038/nature08900; Received 1 December 2009; Accepted 12 February 2010: Published online 3 March 2010.
Traditional herbal Chinese medicine (TCM) has been shown to be effective in killing house dust mites. To quote from this paper, 'These studies suggest that some TCM preparations described herein may be useful as potentially effective, environmentally acceptable, inexpensive, simple and alternative acaricides. Further research is however necessary on the safety issues of these TCM on human health and insecticidal constituents of these extracts.' Promising research on C. cassia, P cablin and E caryophyllata as eco-friendly biodegradable agents for the control of the house dust mite.
Araricidal activities of traditional Chinese medicine against the house dust mite, 'Dermatophagoides farinae'. Hai-Qiang Wu.Jing Li, Zen-Dan He, Zhi-Gang Liu, Parasitology, 2010, 137: 975-983.
This study looks at the relationship between upper and lower airway conditioning in children diagnosed with moderate to severe mite-related rhinitis. By taking two spirometric readings, one at 25% and then 75% (FEF25%-75% ) the clinical team demonstrated that a simple reading of pulmonary volume can be an early warning marker for asthma. The study highlights the close link between the upper and lower airways and the role of some risk factors such as sensitization to mites in children. The article notes previous studies have confirmed this risk assessment for adults.
'Association of childhood perennial allergic rhinitis with subclinical airflow limitations.' Ciprandi G, Capasso M, 'Clin. & Experimental Allergy', 2010; Vol 40: 398-402
The importance of this comprehensive review of asthma to the study of mites can be shown in the following quote, 'In addition to innate defects in [ lung cell ] barrier function and environmental agents such as biologically active allergens (dust mites, pollens, fungi and occupational allergens e.g. protease in washing powders) and virus infections are potent agents that can attack tight junctions.' Tight junctions refers to the 'glue' that binds cells together and acts as important filters. This destructive activity is how the mite's active enzyme/allergen enters the body through eyes, nasal passages, skin or lungs.
'A Brief History of Asthma and Its Mechanisms to Modern Concepts of Disease Pathogenesis', Stephen T Holgate, 'Allergy Asthma Immunol'. 2010, July 2 (3): 165-171.
New research describes how common dust found indoors from house dust mites, dogs, cockroaches and peanuts, can begin an immune cascade towards sensitivity, allergy and asthma. 'Important cells sample the air we breathe in and decide whether or not to activate an immune response'. This is an extremely simple explanation of a ground breaking and' important scientific finding.
'The Mannose Receptor Mediates the Uptake of Diverse Native Allergens by Dendritic Cells and Determines Allergen-Induced T Cell Polarization through Modulation of IDO Activity', Ghaemmaghami AM et al, 'The Journal of Immunology', 2010, 185: 1522-1531
A recent review of the treatment for chronic obstructive pulmonary disease (COPD) in England. It points out that 25% to 45% of patients diagnosed with the disease have never smoked. Yet, almost all of the clinical trials designed to investigate drug remedies for COPD recruit patients who smoke. This throws doubt over the condition itself and pharmacological remedies that may be considered. Severe or poorly controlled asthma is considered a major risk factor for the subsequent development of COPD in non-smokers. Allergens such as from house dust mites are considered a major cause of the symptoms of asthma. Asthma and COPD can exist together in one patient. The Consultation stresses the importance of repeated spirometer readings for lung power, allergen testing and trigger avoidance.
2010 'Consultation Strategy for Services for COPD in England', Department of Health Gateway number 11943, Crown Copyright, 23, Feb, 2010 & The Lancet: (2009) Vol. 374; p733-743
Allergy has increased globally to such an extent that between 20 to 30% of the world's population suffer from some form of allergic disease. Doctors from the World Allergy Organization expressed concern that the majority of patients with common allergic diseases are treated in primary care by physicians with little current knowledge of the basic skills in the science and practice of allergy. They call for all medical students (studying for general practice) to complete a competency course on the recognition, mechanisms and treatment of allergy. The course would include knowledge of common regional allergy triggers such as from house dust mites, pollens, cats, dogs, moulds, insect/venoms, food, drugs, indoor and outdoor pollutants.
'Recommendations for Competency in Allergy Training for Undergraduates Qualifying as Medical Practitioners: A Position Paper of the World Allergy Organization', Potter PC, Warner JO, Pawandar R, Kaliner MA, Del Giacco S, Rosenwasser L, on behalf of the WAO Specialty and Training Council, 'J. Investig. Allergol. Clin. Immunol'. 2010 Vol. 20(3):179-184
Interesting new research demonstrates that house dust mites give off a pheromone that causes the colony to 'clump' together in defense, most probably to stop the colony from drying out. Scientists in the UK have discovered that the pheromone is associated with the food flavoring chemical nerly formate. How to use this pheromone to lure-and-kill a colony is the next step.
Identification of neryl formate as the airborne aggregation pheromone for the American house dust mite and the European house dust mite. (Acari:Epidermoptidae) Skelton AC, Cameron MM, Pickett JA, Birkett MA : 2010, J. Med. Entomol. Vol 47 (5) p798-804
Dangerous non-IgE inflammatory reaction from dust mites is named as a 'New Aspirin Triad'. Scientists are piecing together the reasons why ingestion of mite contaminated wheat flour can result in severe anaphylaxis in a subset of mite allergic patients who are also hypersensitive to non-steroidal anti-inflammatory drugs such as aspirin.
Their success could explain why some episodes of oral or exercise induced anaphylaxis, previously diagnosed as 'of unknown origin', occur. 'They designated the 'New Aspirin Triad' as associated with allergic rhinitis, aspirin/NSAID hypersensitivity and severe reactions to mite-contaminated foodstuff. 'In this subset of atopic mite allergic patients the added non-IgE inflammatory 'load' plus the possibility of aspirin enhanced gut permeability (leading to greater food sensitivity) is key to their investigation. 'Identification of patients 'at risk' and blocking of leukotriene receptors is one future solution identified by the research team.
They base their investigation on recent research that demonstrated that mite and Aspergillus fumigatus extracts stimulate the increased production of non-IgE (cysteinyl leukotriene) inflammation from bone marrow-derived dendritic cells and pulmonary CD11c+cells.
In a separate study doctors consider that Group II allergens from dust mites have properties that can survive the baking process. 'They are stable from heat, to extremes of PH, and to digestion by proteases.
'A novel non-IgE-medicated pathway of mite-induced inflammation'. Sanchez-Borges M, Capriles-Hulett A, Caballero-Fonseca F, J. Allergy Clin. Immunol., 2010; Vol 126, Issue 2: p 403-404
'Dectin-2 recognotion of house dust mite triggers cysteinyl leukotriene generated by dendritic cells' Barrett NA, Maekawa A, Rahman OM, Austen KF, Kanaoka Y, J. Immunol. 2009;182: p1119-1128
'Anaphylaxis after ingestion of wheat flour contaminated with mites', Blanco C. et al. J. Allergy Clin. Immunol. 1997;99:308-313
Authors describe a new way of looking at immunity and call the dust mite enzyme (Der p1) 'dangerous'. Dangerous because, in the new 'two-tiered' description Der p1 can act to skew an immune response towards both adaptive and innate immune reactions. This indicates that the mite enzyme Der p1, can both stimulate sensitization and cause allergic disease.
The authors also note that the dust mite allergen (Der p2) has the ability to mimic an ancient innate immune response, a component of TLR4 complex, and must do this in order to function. This is why the authors refer to Der p2 as a 'bad actor'. Why is this interesting? The TLR4 complex noted is linked to immune sensitization [potentially leading to allergy], as noted in the article.
Dangerous Allergens: Why Some Allergen are Bad Actors
Georas SN, Fezaee F, Lerner L , Beck L, 'Curr. Allergy Asthma Rep.' 2010, 10: 92-98
Soft toys are a major sources of house dust mite allergens, and at a very early age (0-2 years) sleeping with soft toys is strongly associated with house dust mite sensitization Clinical research has identified three practical methods to control mite infestation in soft toys giving parents effective and acceptable methods of limiting house dust mite exposure.' 'Effect of freezing, hot tumble drying and washing with eucalyptus oil on house dust mites in soft toys. 'Pediatric Allergy Immunology', Chang C-F, Wu FF-S, Chen C-y, Crane J, Seibers R. '2011; Doi no: 10.1111/j.1399.2011.01144.
Effect of freezing, hot tumble drying and washing with eucalyptus oil on house dust mites in soft toys. 'Pediatric Allergy Immunology', Chang C-F, Wu FF-S, Chen C-Y, Crane J, Seibers R. 2011; Doi no: 10.1111/j.1399.2011.01144.x.