House Dust Mite


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House Dust Mite

  1. 1. House dust mite Scientific classification Kingdom: AnimaliaPhylum: Arthropoda Class: Arachnida Subclass: Acarina Order: Acariformes Family:Pyroglyphidae Genus: Dermatophagoides Species: D. pteronyssinus Binomial nameDermatophagoides pteronyssinus(Trouessart, 1897)The house dust mite (sometimes referred to by allergists as HDM) is a cosmopolitan guest inhuman habitation. Dust mites feed on organic detritus such as flakes of shed human skin andflourish in the stable environment of dwellings. House dust mites are a common cause ofasthma and allergic symptoms worldwide. The mite’s gut contains potent digestive enzymes(notably proteases) that persist in their feces and are major inducers of allergic reactions suchas wheezing. The mite’s exoskeleton can also contribute to allergic reactions. The Europeanhouse dust mite (Dermatophagoides pteronyssinus) and the American house dust mite(Dermatophagoides farinae) are two different species, but are not necessarily confined toEurope or North America; a third species Euroglyphus maynei also occurs widely.Contents1 Description2 Life cycle3 Habitat and food4 Asthma and allergies5 Common beliefs and misconceptions6 Eradication7 See also8 References[edit] Description9 External linksThe body of a house dust mite is just visible against a dark background in normal light. A typicalhouse dust mite measures 0.4 millimetres (0.016 in) in length and 0.25–0.32 millimetre(0.010–0.013 in) in width.[1] For accurate identification, one needs at least 10× magnification.The body of the house dust mite has a striated cuticle. Like all acari, house dust mites haveeight legs (except the first instar, which has six).[edit] Life cycle 1/8
  2. 2. The average life cycle for a male house dust mite is 10 to 19 days. A mated female house dustmite can last up to 70 days, laying 60 to 100 eggs in the last 5 weeks of her life. In a 10-weeklife span, a house dust mite will produce approximately 2,000 fecal particles and an even largernumber of partially digested enzyme-covered dust particles.[2][edit] Habitat and foodThe house dust mite survives in all climates, even at high altitude. House dust mites thrive in theindoor environment provided by homes, specifically in bedrooms and kitchens. Dust mitessurvive well in mattresses, carpets, furniture and bedding, with figures around 100–500animals/g dust.[3] Even in dry climates, house dust mites survive and reproduce easily inbedding (especially in pillows), which takes up moisture from body contact.[4]House dust mites consume minute particles of organic matter. Like all acari, house dust miteshave a simple gut; they have no stomach but rather diverticulae, which are sacs or pouches thatdivert out of hollow organs. Like many decomposer animals, they select food that has beenalready partially decomposed by fungi.[edit] Asthma and allergiesMain articles: Asthma and AllergyAllergens produced by house dust mites are among the most common triggers of asthma. Thereare at least 15 mite allergens which are subdivided into groups. Group 1 and 2 allergens are themost problematic. Group 1 consists of proteins with a catalytic activity, for example Der p 1(Dermatophagoides pteronyssinus group 1) allergen is a cysteine protease, as is its Americancounterpart Der f 1 (Dermatophagoides farinae group 1). Group 2 are proteins important for themite. Proteins from the other groups affect only few patients. Studies have shown the meanattributable fraction of adult asthma due to atopic sensitization was 30% and 18% forsensitization to dust mites.[5] Taken into consideration this could mean as many as 1.2 billionpeople could have some form of chronic sensitization to dust mites.[5]The allergy occurs because the immune system of allergy affected individuals, for reasons notfully understood, misinterprets a usually innocuous substance as a disease agent and beginsproducing a type of antibody against it, called immunoglobulin E (IgE).[6] This is called the‘primary antibody response.’ The IgE produced during this response binds to basophils in thebloodstream and to a similar type of cell called mast cells in the tissues. When the person againencounters the allergen, these basophils and mast cells that have bound to IgE releasehistamine, prostaglandins and leukotrienes, which causes inflammation of the surroundingtissues, resulting in allergic symptoms. Most treatment has relied so far on trying to counteractthe released chemicals with anti-histamines, corticosteroids or Salbutamol. Commercial brandsof these medications most commonly prescribed to treat Asthma include Ventolin and Seretide.Newer methods to try to treat house dust mite allergy involve immunotherapy. A safety andtolerability clinical trial (Phase IIa) has been completed with positive results by CytosBiotechnology using an immunotherapeutic (CYT003-QbG10) for treatment of house dust 2/8
  3. 3. mite-triggered allergies.[7]A 10 year controlled study in 60 mite sensitised, asthmatic children, showed almost completeremission of asthma in those treated with sublingual immunotherapy (SLIT), and that thisremission was still apparent 5 years beyond the completion of treatment. [8]This finding was supported by a review of 39 mite triggered asthmatic children, who weresuffering an average of 8 acute exacerbations per year. After treatment with SLIT, theexacerbation rate was reduced by 95%. [9]The French biopharmaceutical company Stallergenes is developing, via the Stalair Program,sublingual desensitization treatments for house dust mite allergy. The immunotherapy tablet,“Actair”, has demonstrated efficacy after 4 months of treatment and the persistence of itstherapeutic effect after only one year of treatment. (study VO57.07 conducted in Europe)Stallergenes is now preparing filing NDA in Germany. A phase III pediatric study has beenlaunched.Typical symptoms of house dust mite allergies are itchiness; sneezing; inflamed or infectedeczema skin; watering/reddening eye; sneezing repeatedly and frequently, e.g., on waking up orsneezing 10 or more times; runny nose; and clogging in the lungs.Dust mite immunotherapy is still not widespread, especially in countries such the UK. If allergicasthmatic children cannot get access to desensitisation, then the best form of treatment for dustmite allergies remains one of avoidance, although this requires a high level of commitment frompatient/parents. It is important however, to maintain use of medication such as anti-histamines,corticosteroids or Salbutamol. The environment of bedding is optimal for most dust mites, andcomparative studies have shown that the density of dust mites in mattresses is on averagegreater than 2500/gram of dust.[10] Cleaning beds with most vacuum cleaners will not removedust mite allergens, but instead throw them into the air and increase their volatility. Somepolyethylene bedding is beneficial as it makes the environment difficult for the dust mites. Thisbedding should also be breathable and be able to withstand frequent washing. A home allergenreduction plan has been recognized as being an essential part to the management of asthmasymptoms,[11] and therefore all aspects of the home environment should be considered (propervacuuming, use of air cleaners, etc.). The Asthma and Allergy Foundation of America as well asthe Asthma Society of Canada certify products that may be used in a home allergen reductionplan in a Program called Asthma and Allergy Friendly.[edit] Common beliefs and misconceptionsIt is commonly believed that the accumulated detritus from dust mites can add significantly tothe weight of mattresses and pillows. While some recent studies have supported this claim,[12]other reports dispute it.[13] However, more scientific evidence is needed for a completeconsensus.Allergy and asthma sufferers are also often advised to avoid feather pillows due to thepresumed increased presence of the house dust mite allergen (Der p I). The reverse, however, 3/8
  4. 4. is true. A 1996 study from the British Medical Journal has shown that polyester fibre pillowscontained more than 8 times the total weight of Der p I and 3.57 times more micrograms of Derp I per gram of fine dust than feather pillows.[14][edit] EradicationHouse dust mites reproduce quickly enough that their effect on human health can be significant.Since dust mites depend on moisture to survive, they are most often found in bedding such aspillows and duvets.[1] Dust mites numbers can be reduced by replacing carpets with flatsurfaces that are easier to vacuum and maintaining relative humidity below 50%.[15] Existingmites can be eradicated by regularly cleaning and washing items that harbour them, exposingthem to temperatures over 60 °C (140 °F) for a period of one hour or to temperatures below 0°C (32 °F),[16][citation needed] through ten minutes’ exposure to the lethal temperatures –near 105 °C (221 °F) – in a household clothes dryer,[17] or using disodium octaboratetetrahydrate (DOT) powder.[18] A side-effect of DOT is irritation of eyes.[edit] See also[edit] ReferencesList of mites associated with cutaneous reactions^ a b Ella Davies (December 21, 2010). “Dust mites ‘swarm’ around houses”. BBC News. Retrieved September11, 2012.^ “Allergia agli acari” (in Italian).^ “House Dust Allergy”. American College of Allergy, Asthma & Immunology. September 12, 2012.^ G. Daniel Brooks & Robert K. Bush (2009). “Allergens and other factors important in atopicdisease”. In Leslie Carroll Grammer & Paul A. Greenberger. Patterson’s Allergic Diseases (7thed.). Lippincott Williams & Wilkins. pp. 73–103. ISBN 978-0-7817-9425-1.^ a b Xavier Basagaña, Jordi Sunyer, Manolis Kogevinas, Jan-Paul Zock, Enric Duran-Tauleria,Deborah Jarvis, Peter Burney, Josep Maria Anto, and on behalf of the European CommunityRespiratory Health Survey (2004). “Socioeconomic Status and Asthma Prevalence in YoungAdults. The European Community Respiratory Health Survey”. American Journal ofEpidemiology 160 (2): 178–188. doi:10.1093/aje/kwh186. PMID 15234940.^ J.-Y. Shim, B.-S. Kim, S.-H. Cho, K.-U. Min & S.-J. Hong (2003). “Allergen-specificconventional immunotherapy decreases immunoglobulin E-mediated basophil histaminereleasability”. Clinical & Experimental Allergy 33 (1): 52–57.doi:10.1046/j.1365-2222.2003.01567.x. PMID 12534549.^ Staff (June 15, 2007). “Clinical Trials Update: Allergies”. Genetic Engineering &Biotechnology News (Mary Ann Liebert, Inc.): p. 52.^ Di Rienzo et al (2003). “Long-lasting effect of sublingual immunotherapy in children withasthma due to house dust mite: a 10-year prospective study”. Clin Exp Allergy 33: 206-210.^ Nuhoglu et al (2007). “Sublingual Immunotherapy to House Dust Mite in Pediatric PatientsWith Allergic Rhinitis and Asthma: A Retrospective Analysis of Clinical Course Over a 3-YearFollow-up Period”. J Investig Allergol Clin Immunol 17 (6): 375-378. 4/8
  5. 5. ^ Korsgaard, J; Iversen, M (1991). “Epidemiology of house dust mite allergy”. Allergy 46 Suppl11: 14–8. doi:10.1111/j.1398-9995.1991.tb00643.x. PMID 1897695.^ “Guidelines for the diagnosis and management of asthma.”. National Heart Lung and BloodInstitute. 2007.^ MacRae, Fiona (June 22, 2011). “How your pillow is the perfect breeding ground forgruesome array of pests and diseases”. Daily Mail.^ “Does a mattress double its weight due to dust mites and their debris?”.^ T. J. Kemp, R. W. Siebers, D. Fishwick, G. B. O’Grady, P. Fitzharris & J. Crane (October 121996). “House dust mite allergen in pillows”. British Medical Journal 313 (7062): 916–919.doi:10.1136/bmj.313.7062.916. PMC 2352227. PMID 8876094. “For many years asthmatic patients havebeen told to avoid using feather filled pillows on their beds, although there is no evidence tosupport this practice. Strachan and Carey’s case-control study is the first to have directlychallenged this assumption.1 This study showed that, after exclusion of asthmatic subjectswhose bedding had been changed because of their disease, pillows with synthetic fillings werea risk factor for severe asthma. In the light of this finding, we have compared pillows withsynthetic and feather fillings for their content of Der p I, the major allergen of the house dustmite Dermatophagoides pteronyssinus.”^ Choi, SY; Lee, IY; Sohn, JH; Lee, YW; Shin, YS; Yong, TS; Hong, CS; Park, JW (2008).“Optimal conditions for the removal of house dust mite, dog dander, and pollen allergens usingmechanical laundry”. Annals of allergy, asthma & immunology : official publication of theAmerican College of Allergy, Asthma, & Immunology 100 (6): 583–8.doi:10.1016/S1081-1206(10)60060-9. PMID 18592823.^ “Dust Mites, Do they do any good in the world?”.^ J. D. Miller, A. Miller (1996). “Ten minutes in a clothes dryer kills all mites in blankets”.Journal of Allergy and Clinical Immunology 97 (1, part 3): 423.doi:10.1016/S0091-6749(96)81180-8.^ R. Codina, R. F. Lockey, R. Diwadkar, L. L. Mobly & S. Godfrey (2003). “Disodium octaboratetetrahydrate (DOT) application and vacuum cleaning, a combined strategy to control house dustmites”. Allergy 58 (4): 318–324. doi:10.1034/j.1398-9995.2003.00100.x. PMID 12708980.[edit] External links Arthropods portalHouse Dust Mite site with research, animations and advice for patients and parents.Dust Mite Information – Allergies, biology, control measures and locating dust mitesHouse dust mites on the University of Florida / Institute of Food and Agricultural SciencesFeatured Creatures websitevte 5/8
  6. 6. Acari (ticks and mites)AcariformesTrombidiformesSphaerolichidaProstigmataSarcoptiformesEndeostigmataOribatidaParasitiformesOpilioacariformesOpilioacaridaeHolothyridaAllothyridaeHolothyridaeNeothyridaeIxodida (ticks)ArgasidaeIxodidaeNuttalliellidae 6/8
  7. 7. MesostigmataSejidaSejoideaTrigynaspidaCercomegistoideaAntennophoroideaCelaenopsoideaFedrizzioideaMegisthanoideaParantennuloideaAenictequoideaMonogynaspidaMicrogynioideaHeatherelloideaThinozerconoideaPolyaspidoideaUropodoideaTrachyuropodoideaDiarthrophalloideaEpicrioideaZerconoideaArctacaroideaParasitoideaVeigaioideaRhodacaroideaEviphidoideaAscoideaPhytoseioideaDermanyssoideaThis article uses material from the Wikipedia article House Dust Mite, which is released underthe Creative Commons Attribution-Share-Alike License 3.0. 7/8
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