House dust mite
Encyclopedia
The house dust mite is a cosmopolitan
guest in human
habitation. Dust mite
s feed on organic detritus such as flakes of shed human skin and flourish in the stable environment of dwellings. House dust mites are a common cause of asthma
and allergic symptoms worldwide. The mite's gut contains potent digestive enzymes (notably protease
s) that persists in their feces and are major inducers of allergic reactions such as wheezing. The mite's exoskeleton can also contribute to allergic reactions. The European house dust mite (Dermatophagoides pteronyssinus) and the American house dust mite (Dermatophagoides farinae) are two different species, but are not necessarily confined to Europe or North America; a third species Euroglyphus maynei also occurs widely.
. Like all acari, house dust mites have eight legs (except 3 pairs in the first instar).
House dust mites consume minute particles of organic matter. Like all acari, house dust mites have a simple gut; they have no stomach but rather diverticulae, which are sacs or pouches that divert out of hollow organs. Like many decomposer animals, they select food that has been already partially decomposed by fungi.
s produced by house dust mites are among the most common triggers of asthma. There are at least 15 mite allergens which are subdivided into groups. Group 1 and 2 allergens are the most 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 American counterpart Der f 1 (Dermatophagoides farinae group 1). Group 2 are proteins important for the mite. Proteins from the other groups affect only few patients.
Studies have shown the mean attributable fraction of adult asthma due to atopic sensitization was 30% and 18% for sensitization to dust mites. Taken into consideration this could mean as many as 1.2 billion people could have some form of chronic
sensitization to dust mites.
The allergy occurs because the immune system
of allergy affected individuals, for reasons not fully understood, misinterprets a usually innocuous substance as a disease agent and begins producing a type of antibody
against it, called immunoglobulin E
(IgE). This is called the 'primary antibody
response.' The IgE produced during this response binds to basophils in the bloodstream and to a similar type of cell called mast cells in the tissues. When the person again encounters the allergen
, these basophils and mast cells that have bound to IgE release histamine
, prostaglandin
s and leukotriene
s, which causes inflammation of the surrounding tissues, resulting in allergic symptoms. Most treatment has relied so far on trying to counteract the released chemicals with anti-histamines, corticosteroid
s or Salbutamol
. Commercial brands of 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 and tolerability clinical trial
(Phase IIa) has been completed with positive results by Cytos Biotechnology using an immunotherapeutic (CYT003-QbG10) for treatment of house dust mite-triggered allergies. 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 its therapeutic 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 been launched.
Typical symptom
s of house dust mite allergies are itchiness, sneezing, inflamed or infected eczema
, watering/reddening eyes, sneezing repeatedly and frequently; e.g., on waking up sneezing 10 or more times, runny nose and clogging in the lungs.
At present, the best form of treatment for dust mite allergies is avoidance of dust mites and their allergens combined with medication such as anti-histamines, corticosteroid
s or Salbutamol
. The environment of bedding is optimal for most dust mites, and comparative studies have shown that the density of dust mites in mattresses to be on average greater than 2500/gram of dust. Cleaning beds with most vacuum cleaners will not remove dust mite allergens, but instead throw them into the air and increase their volatility. Some polyethylene
bedding is beneficial as it makes the environment difficult for the dust mites. This bedding should also be breathable and be able to withstand frequent washing. A home allergen reduction plan has been recognized as being an essential part to the management of asthma symptoms. and therefore all aspects of the home environment should be considered (proper vacuuming, use of air cleaners, etc.). The Asthma and Allergy Foundation of America
as well as the Asthma Society of Canada
certify products that may be used in a home allergen reduction plan in a Program called Asthma and Allergy Friendly
.
Allergy and asthma sufferers are also often advised to avoid feather pillows due to the presumed increased presence of the house dust mite allergen (Der p I). The reverse, however, is true. A 1996 study from the British Medical Journal
has shown that polyester fibre pillows contained more than 8 times the total weight of Der p I and 3.57 times more micrograms of Der p I per gram of fine dust than feather pillows.
powder is often used to eradicate house dust mites.
A simple washing will remove most of the waste matter. Exposure to temperatures over 60 °C (140 °F) for a period of one hour or freezing, exposure to temperatures below 0 °C (32 °F), will typically prove fatal to house dust mites; a relative humidity
less than 50% may also be fatal. Ten minutes in a household clothes dryer at lethal temperatures has been shown to be sufficient to kill all the dust mites in bedding. House dust mites reproduce quickly enough that their effect on human health can be significant.
As dust mites like warm, fluffy furniture and materials, they are most likely to be found on beds, couches, carpets, rugs, toys, and curtains. Washing will not completely remove all mites or their droppings, but it will remove at least 90%. It is best to have a carpet free house if dust mites or any house pests are dangerous for a person (e.g., because of their allergy), as flat surfaces are easier to clean and vacuum. If a person is allergic to dust mites, anti-mite mattresses or mattresses which prevent any house pests should be used. Regular cleaning and washing of areas where dust mites thrive is necessary to keep them and their waste to a minimum.
Cosmopolitan distribution
In biogeography, a taxon is said to have a cosmopolitan distribution if its range extends across all or most of the world in appropriate habitats. For instance, the killer whale has a cosmopolitan distribution, extending over most of the world's oceans. Other examples include humans, the lichen...
guest in human
Human
Humans are the only living species in the Homo genus...
habitation. Dust mite
Mite
Mites, along with ticks, are small arthropods belonging to the subclass Acari and the class Arachnida. The scientific discipline devoted to the study of ticks and mites is called acarology.-Diversity and systematics:...
s feed on organic detritus such as flakes of shed human skin and flourish in the stable environment of dwellings. House dust mites are a common cause of asthma
Asthma
Asthma is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm. Symptoms include wheezing, coughing, chest tightness, and shortness of breath...
and allergic symptoms worldwide. The mite's gut contains potent digestive enzymes (notably protease
Protease
A protease is any enzyme that conducts proteolysis, that is, begins protein catabolism by hydrolysis of the peptide bonds that link amino acids together in the polypeptide chain forming the protein....
s) that persists in their feces and are major inducers of allergic reactions such as wheezing. The mite's exoskeleton can also contribute to allergic reactions. The European house dust mite (Dermatophagoides pteronyssinus) and the American house dust mite (Dermatophagoides farinae) are two different species, but are not necessarily confined to Europe or North America; a third species Euroglyphus maynei also occurs widely.
Size
The body of a house dust mite is just visible against a dark background in normal light. A typical house dust mite measures 0.4 millimetre (0.015748031496063 in) in length and 0.25–0.32 mm (0.00984251968503937–0.0125984251968504 ) in width. Both male and female adult house dust mites are creamy blue and have a rectangular shape. The body of the house dust mite also contains a striated cuticleCuticle
A cuticle , or cuticula, is a term used for any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticles" are non-homologous; differing in their origin, structure, function, and chemical composition...
. Like all acari, house dust mites have eight legs (except 3 pairs in the first instar).
Life cycle
The average life cycle for a male house dust mite is 10 to 19 days. A mated female house dust mite can last up to 70 days, laying 60 to 100 eggs in the last 5 weeks of her life. In a 10-week life span, a house dust mite will produce approximately 2,000 fecal particles and an even larger number of partially digested enzyme-covered dust particles.Habitat and food
The house dust mite survives in all climates, even at high altitude. House dust mites thrive in the indoor environment provided by homes, specifically in bedrooms and kitchens. Dust mites survive well in mattresses, carpets, furniture and bedding, with figures around 188 animals/g dust. Even in dry climates, house dust mites survive and reproduce easily in bedding (especially in pillows), deriving moisture from humidity in the air.House dust mites consume minute particles of organic matter. Like all acari, house dust mites have a simple gut; they have no stomach but rather diverticulae, which are sacs or pouches that divert out of hollow organs. Like many decomposer animals, they select food that has been already partially decomposed by fungi.
Asthma and allergies
AllergenAllergen
An allergen is any substance that can cause an allergy. In technical terms, an allergen is a non-parasitic antigen capable of stimulating a type-I hypersensitivity reaction in atopic individuals....
s produced by house dust mites are among the most common triggers of asthma. There are at least 15 mite allergens which are subdivided into groups. Group 1 and 2 allergens are the most problematic. Group 1 consists of proteins with a catalytic activity, for example Der p 1 (Dermatophagoides pteronyssinus group 1) allergen is a cysteine protease
Cysteine protease
Proteases are enzymes that degrade polypeptides. Cysteine proteases have a common catalytic mechanism that involves a nucleophilic cysteine thiol in a catalytic dyad. The first step is deprotonation of a thiol in the enzyme's active site by an adjacent amino acid with a basic side chain, usually a...
, as is its American counterpart Der f 1 (Dermatophagoides farinae group 1). Group 2 are proteins important for the mite. Proteins from the other groups affect only few patients.
Studies have shown the mean attributable fraction of adult asthma due to atopic sensitization was 30% and 18% for sensitization to dust mites. Taken into consideration this could mean as many as 1.2 billion people could have some form of chronic
Chronic
Chronic may refer to:* Chronic , a disease that is long-lasting and reoccurring.* Chronic toxicity, a substance with toxic effects after continuous or repeated exposure* The Chronic, a 1992 album by Dr. Dre...
sensitization to dust mites.
The allergy occurs because the immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
of allergy affected individuals, for reasons not fully understood, misinterprets a usually innocuous substance as a disease agent and begins producing a type of antibody
Antibody
An antibody, also known as an immunoglobulin, is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes a unique part of the foreign target, termed an antigen...
against it, called immunoglobulin E
Immunoglobulin E
Immunoglobulin E is a class of antibody that has been found only in mammals. IgE is a monomeric antibody with 4 Ig-like domains...
(IgE). This is called the 'primary antibody
Antibody
An antibody, also known as an immunoglobulin, is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes a unique part of the foreign target, termed an antigen...
response.' The IgE produced during this response binds to basophils in the bloodstream and to a similar type of cell called mast cells in the tissues. When the person again encounters the allergen
Allergen
An allergen is any substance that can cause an allergy. In technical terms, an allergen is a non-parasitic antigen capable of stimulating a type-I hypersensitivity reaction in atopic individuals....
, these basophils and mast cells that have bound to IgE release histamine
Histamine
Histamine is an organic nitrogen compound involved in local immune responses as well as regulating physiological function in the gut and acting as a neurotransmitter. Histamine triggers the inflammatory response. As part of an immune response to foreign pathogens, histamine is produced by...
, prostaglandin
Prostaglandin
A prostaglandin is any member of a group of lipid compounds that are derived enzymatically from fatty acids and have important functions in the animal body. Every prostaglandin contains 20 carbon atoms, including a 5-carbon ring....
s and leukotriene
Leukotriene
Leukotrienes are fatty signaling molecules. They were first found in leukocytes . One of their roles is to trigger contractions in the smooth muscles lining the trachea; their overproduction is a major cause of inflammation in asthma and allergic rhinitis...
s, which causes inflammation of the surrounding tissues, resulting in allergic symptoms. Most treatment has relied so far on trying to counteract the released chemicals with anti-histamines, corticosteroid
Corticosteroid
Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiologic systems such as stress response, immune response and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte...
s or Salbutamol
Salbutamol
Salbutamol or albuterol is a short-acting β2-adrenergic receptor agonist used for the relief of bronchospasm in conditions such as asthma and chronic obstructive pulmonary disease. It is marketed as Ventolin among other brand names....
. Commercial brands of these medications most commonly prescribed to treat Asthma
Asthma
Asthma is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm. Symptoms include wheezing, coughing, chest tightness, and shortness of breath...
include Ventolin
Ventolin
Ventolin may refer to:* Salbutamol, bronchodilator medication marketed under the brand name Ventolin amongst others.* "Ventolin" , a song and single by Richard D James/Aphex Twin, named after the medicine...
and Seretide.
Newer methods to try to treat house dust mite allergy
Allergy
An Allergy is a hypersensitivity disorder of the immune system. Allergic reactions occur when a person's immune system reacts to normally harmless substances in the environment. A substance that causes a reaction is called an allergen. These reactions are acquired, predictable, and rapid...
involve immunotherapy
Immunotherapy
Immunotherapy is a medical term defined as the "treatment of disease by inducing, enhancing, or suppressing an immune response". Immunotherapies designed to elicit or amplify an immune response are classified as activation immunotherapies. While immunotherapies that reduce or suppress are...
. A safety and tolerability clinical trial
Clinical trial
Clinical trials are a set of procedures in medical research and drug development that are conducted to allow safety and efficacy data to be collected for health interventions...
(Phase IIa) has been completed with positive results by Cytos Biotechnology using an immunotherapeutic (CYT003-QbG10) for treatment of house dust mite-triggered allergies. The French
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
biopharmaceutical
Biopharmaceutical
Biopharmaceuticals are medical drugs produced using biotechnology. They include proteins , nucleic acids and living microorganisms like virus and bacteria where the virulence of viruses and bacteria is reduced by the process of attenuation, they can be used for therapeutic or in vivo diagnostic...
company Stallergenes
Stallergenes
Stallergenes is a European biopharmaceutical company specialized in the manufacture of immunotherapy medicines for the prevention and treatment of allergic respiratory diseases such as rhinoconjunctivitis and allergic asthma. It is Europe’s second largest maker of allergy medicines, conducts 85% of...
is developing, via the Stalair Program, sublingual
Sublingual
Sublingual, literally 'under the tongue', from Latin, refers to the pharmacological route of administration by which drugs diffuse into the blood through tissues under the tongue...
desensitization treatments for house dust mite allergy. The immunotherapy tablet, "Actair", has demonstrated efficacy after 4 months of treatment and the persistence of its therapeutic effect after only one year of treatment. (study VO57.07 conducted in Europe) Stallergenes
Stallergenes
Stallergenes is a European biopharmaceutical company specialized in the manufacture of immunotherapy medicines for the prevention and treatment of allergic respiratory diseases such as rhinoconjunctivitis and allergic asthma. It is Europe’s second largest maker of allergy medicines, conducts 85% of...
is now preparing filing NDA in Germany. A phase III pediatric study has been launched.
Typical symptom
Symptom
A symptom is a departure from normal function or feeling which is noticed by a patient, indicating the presence of disease or abnormality...
s of house dust mite allergies are itchiness, sneezing, inflamed or infected eczema
Eczema
Eczema is a form of dermatitis, or inflammation of the epidermis . In England, an estimated 5.7 million or about one in every nine people have been diagnosed with the disease by a clinician at some point in their lives.The term eczema is broadly applied to a range of persistent skin conditions...
, watering/reddening eyes, sneezing repeatedly and frequently; e.g., on waking up sneezing 10 or more times, runny nose and clogging in the lungs.
At present, the best form of treatment for dust mite allergies is avoidance of dust mites and their allergens combined with medication such as anti-histamines, corticosteroid
Corticosteroid
Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiologic systems such as stress response, immune response and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte...
s or Salbutamol
Salbutamol
Salbutamol or albuterol is a short-acting β2-adrenergic receptor agonist used for the relief of bronchospasm in conditions such as asthma and chronic obstructive pulmonary disease. It is marketed as Ventolin among other brand names....
. The environment of bedding is optimal for most dust mites, and comparative studies have shown that the density of dust mites in mattresses to be on average greater than 2500/gram of dust. Cleaning beds with most vacuum cleaners will not remove dust mite allergens, but instead throw them into the air and increase their volatility. Some polyethylene
Polyethylene
Polyethylene or polythene is the most widely used plastic, with an annual production of approximately 80 million metric tons...
bedding is beneficial as it makes the environment difficult for the dust mites. This bedding should also be breathable and be able to withstand frequent washing. A home allergen reduction plan has been recognized as being an essential part to the management of asthma symptoms. and therefore all aspects of the home environment should be considered (proper vacuuming, use of air cleaners, etc.). The Asthma and Allergy Foundation of America
Asthma and Allergy Foundation of America
The Asthma and Allergy Foundation of America is a non-profit organization dedicated to finding a cure for and controlling asthma, food allergies, nasal allergies and other allergic diseases. AAFA's mission is also to educate the public about these diseases...
as well as the Asthma Society of Canada
Asthma Society of Canada
The Asthma Society of Canada is a non profit charity dedicated to enhancing the quality of life and health for people living with asthma and associated allergies through education and research. The vision of the ASC is to empower every child and adult with asthma in Canada to live an active and...
certify products that may be used in a home allergen reduction plan in a Program called Asthma and Allergy Friendly
Asthma and Allergy Friendly
Asthma & Allergy Friendly is a registered certification mark operated by Allergy Standards Limited in association with not-for-profit asthma and/or allergy organizations, labeling products which have been put through and have passed standardised testing....
.
Myths and misconceptions
It is commonly believed that the accumulated detritus from dust mites can add significantly to the weight of mattresses and pillows. While it is true that the fecal matter of dust mites will increase over time, there is no scientific evidence for these claims.Allergy and asthma sufferers are also often advised to avoid feather pillows due to the presumed increased presence of the house dust mite allergen (Der p I). The reverse, however, is true. A 1996 study from the British Medical Journal
British Medical Journal
BMJ is a partially open-access peer-reviewed medical journal. Originally called the British Medical Journal, the title was officially shortened to BMJ in 1988. The journal is published by the BMJ Group, a wholly owned subsidiary of the British Medical Association...
has shown that polyester fibre pillows contained more than 8 times the total weight of Der p I and 3.57 times more micrograms of Der p I per gram of fine dust than feather pillows.
Eradication
Disodium octaborate tetrahydrateDisodium octaborate tetrahydrate
Disodium octaborate tetrahydrate, an alkaline salt, is produced in two forms. One is a clear, liquid concentrate, which can be mistaken for corn syrup if repackaged and not properly labeled or it is packaged as a white, odorless, powdered chemical substance that is not flammable, combustible, or...
powder is often used to eradicate house dust mites.
A simple washing will remove most of the waste matter. Exposure to temperatures over 60 °C (140 °F) for a period of one hour or freezing, exposure to temperatures below 0 °C (32 °F), will typically prove fatal to house dust mites; a relative humidity
Relative humidity
Relative humidity is a term used to describe the amount of water vapor in a mixture of air and water vapor. It is defined as the partial pressure of water vapor in the air-water mixture, given as a percentage of the saturated vapor pressure under those conditions...
less than 50% may also be fatal. Ten minutes in a household clothes dryer at lethal temperatures has been shown to be sufficient to kill all the dust mites in bedding. House dust mites reproduce quickly enough that their effect on human health can be significant.
As dust mites like warm, fluffy furniture and materials, they are most likely to be found on beds, couches, carpets, rugs, toys, and curtains. Washing will not completely remove all mites or their droppings, but it will remove at least 90%. It is best to have a carpet free house if dust mites or any house pests are dangerous for a person (e.g., because of their allergy), as flat surfaces are easier to clean and vacuum. If a person is allergic to dust mites, anti-mite mattresses or mattresses which prevent any house pests should be used. Regular cleaning and washing of areas where dust mites thrive is necessary to keep them and their waste to a minimum.
External links
- House Dust Mite site with research, animations and advice for patients and parents.
- Dust Mite Information – Allergies, biology, control measures and locating dust mites
- House dust mites on the University of FloridaUniversity of FloridaThe University of Florida is an American public land-grant, sea-grant, and space-grant research university located on a campus in Gainesville, Florida. The university traces its historical origins to 1853, and has operated continuously on its present Gainesville campus since September 1906...
/ Institute of Food and Agricultural SciencesInstitute of Food and Agricultural SciencesThe University of Florida’s Institute of Food and Agricultural Sciences is a federal-state-county partnership dedicated to developing knowledge in agriculture, human and natural resources, and the life sciences, and enhancing and sustaining the quality of human life by making that information...
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