d1 House dust mite

Summary

DermatophagoidesSummary pteronyssinus (Der p) is a house dust mite specie originally found in house dust. This domestic mite is highly allergenic, and exposure to its allergens in sensitized individuals is one of the most common cause of respiratory allergic diseases in the world. The main exposure route is inhalation and symptoms typically affects the upper and lower airways and eyes, causing allergic rhinitis, asthma, and sometimes anaphylaxis. Exposure via the skin can cause atopic dermatitis. Several Der p allergens have been characterized and are present on airborne fecal and body particles. Extensive IgE cross-reactivity exists between Der p and other house dust mite species. Partial cross-reactivity has been demonstrated to storage mite species. Cross-reactivity also exists among allergens in Der p and related arthropods including crustaceans (shrimp, crab, and lobster) and insects (cockroach, grasshopper), as well as members of the mollusk phylum (snails, clams, oysters, and squid. Management of house dust mite allergy includes avoidance, pharmacotherapy and specific allergen immunotherapy (AIT).

Allergen

Nature

Unique characteristics of dust mites have allowed them to colonize the indoor environment in temperate regions of the world. Other traits facilitate the delivery of their allergens into close contact with skin and mucosal epithelium. House dust mites, including D pteronyssinus, produce a complex range of allergens and adjuvants which act together to induce both innate and adaptive immune reactions. Accordingly, the induction of allergy to these mites is an important cause of respiratory allergies, and the exposure of already sensitized individuals to mite products is a significant trigger of asthma exacerbations (Calderon 2015). 

Taxonomy

Dust mites belong to the phylum Arthropoda, class Arachnida. Within this phylum are 2 other classified groups which contain species having an important role in allergic disease, namely the class insects and subphylum crustacea (Miller 2019).

Some insects and arachnids are the source of important inhalant allergens, while some crustaceans are a major source of food allergens. During evolution, arthropods separated from other animals approximately 600 million years ago and the major classes were established within 100 million years.  Dust mites and insects such as cockroaches have therefore been separated for at least 400 million years (Miller 2019). 

Despite the huge number of arthropod species, only a few have been implicated as sources of indoor allergens and 90% of the related literature covers only five genera: Dermatophagoides, Blomia, Euroglyphus, Blatella and Periplaneta. Similarly, although multiple species of mites have been identified in indoor environments, only a few have been causally associated with allergic disease, namely D. pteronyssinus, D. farinae, Euroglyphus maynei and Blomia tropicalis (Miller 2019).

Tissue

Mite allergens come into contact with respiratory mucosa and skin via fecal particles, and to a much lesser extent via fragments of mite bodies. During its lifetime a mite produces approximately 1000 solid fecal waste particles of approximately 20 – 25 µ in diameter. This size of particle is capable of penetrating both upper and lower airways, thus coming into contact with lung mucosa as well as more superficial sites such as skin or eyes (Tovey 1981a, Tovey 1981b).

Mite fecal particles contain high concentrations of molecules, some which are allergenic proteins. More than 80% of mite allergen is on particles >10 μ and is undetectable in the air of undisturbed rooms. Fecal particles become transiently airborne during disturbance brought about by human activities such as sweeping, vacuuming or changing bedding. The particles are also an important source of other molecules, such as nucleic acids, that have adjuvant properties via interaction with toll-like receptors or pattern recognition receptors (PRRs) which recognize pathogen associated molecular patterns (PAMPS). Chitin, mite DNA, bacterial DNA, and endotoxin are known PAMPS found in house dust mite feces and bodies. The fecal particles can thus induce an IgE response but also contribute to non-allergen specific inflammation in the nose, lungs and skin  (Tovey 1981a, Tovey 1981b).

Epidemiology   

Worldwide distribution

Dust mites are found worldwide, except in cold, dry high-altitude regions, polar areas, and extremely arid desert zones. House dust mites thrive in temperate climates, particularly in households and dwellings with damp and humid conditions. Allergens from the species D. pteronyssinus and D. farinae are commonly found in dust samples from homes, indicating the presence of both species in the same environment. Within any given geographical area, dust mites vary in their distribution among specific regions and with the seasons (Zheng 2015). D. farinae can tolerate dryer environmental conditions. D. pteronyssinus tends to be more abundant in Europe than in the United States. In northern areas of Europe where the climate is extremely dry, dust mites may not survive the winter.

High altitude is generally inhospitable to house dust mites, which may partly explain why, before the discovery of dust mites, sanitaria for asthma and other respiratory diseases were often built at high altitudes, such as the Alps in Europe and Colorado in the USA. Dust mite growth (Vervloet 1982) and sensitization (Charpin 1991) are much lower in the Alps than at sea level, the apparent result of the lower indoor humidity at high altitude.

Living environment

Dust mites are most prevalent in households, where they thrive in dark environments and burrow deep into soft substrates like carpets, pillows, mattresses, and clothing (Schroer 2008). A higher mite allergen exposure has been correlated with higher education, higher household income, and lower population density in the home (Leaderer 2002). Mite allergen levels are reported higher in older homes and non-air conditioned dwellings (van Strien 2004). A study from China found significant enrichment of house dust mite major allergens in air-conditioner filters located in dining rooms, shopping malls, hotels, and households. The concentration of Der p 1 in the air increased notably one hour after the air-conditioners were turned on (Zhan 2015).

Route of Exposure         

Main route

House dust mite allergens trigger allergic reactions primarily through inhalation of mite fecal particles and body fragments, which become airborne after disturbances like vacuuming or making the bed. 

Other routes

Other routes include direct skin contact with contaminated bedding or furniture and accidental ingestion of mite particles by consumption of contaminated foods (Millner 2019).

Clinical Relevance

Allergic rhinitis

Significant proportions of the allergic rhinitis patients and chronic rhinosinusitis patients with allergy are sensitized to house dust mites (Rolla 2007). The link between allergen sensitization and symptoms can be demonstrated using nasal challenge with mite allergen, which produces obstruction and rhinorrhea that correlate with mite skin test reactivity (Chusakul 2010).

Information on the occurrence of ocular symptoms in association with allergic rhinitis is sparse, but one study of patients with allergic rhinitis to a variety of allergens including dust mites, found that most individuals also had ocular involvement with symptoms of pruritus, tearing, conjunctival injection, and eyelid edema (Klossek 2012).

Asthma

Dust mites including D pteronyssinus are one of the most frequent causes of respiratory allergies and mite exposure is a very important factor eliciting exacerbations of asthma (Calderon 2015). 

Mite allergen exposure as a trigger to exacerbate existing asthma has been clearly and repeatedly demonstrated (Miller 2019). The inhalation of dust mite allergen can have effects beyond bronchospasm, decreasing mucociliary clearance and thus increasing the deposition of other inhaled particles. The combination of mite sensitization and mite exposure together correlate with the severity of asthma symptoms (Tunnicliffe 1999), with increased exhaled nitric oxide and bronchial hyper-reactivity (Langley 2003) and with acute exacerbations resulting in admission to hospital (Sporik 1993).

Sensitization to Dermatophagoides mites also appears to exacerbate asthma attacks in children suffering from rhinovirus infections (Soto-Quiros 2012). The addition of viral infection to allergen exposure in mite-sensitized individuals results in more severe attacks with acute wheezing (Soto-Quiros 2012) and hospitalization (Green 2002, Murray 2006).

Mite allergy is a major risk factor for asthma and mite sensitization early in life has a significant impact on subsequent pulmonary function. One multicenter, birth cohort study followed 1314 children from birth to 13 years of age  (Illi 2006). Asthma symptoms and lung function, specific IgE, and perennial allergen exposure (mite, cat and dog dander) were assessed at regular intervals. The great majority (90%) of children with wheeze but no sensitization had lost their symptoms by school age and retained normal lung function at puberty. In contrast, sensitization to perennial allergens including mite, which developed in the first 3 years of life was correlated with compromised lung function at school age.  Sensitization and exposure occurring later than 3 years of age resulted in much weaker effects on lung function, and sensitization to seasonal allergens such as pollens had no effect on subsequent lung function (Illi 2006).

Atopic Dermatitis

The prevalence of sensitization to mites can be very high in patients with atopic dermatitis. The increase in the permeability of atopic skin and the ability of mite proteases to decrease skin barrier function may allow more effective sensitization with aeroallergens, initiating a cycle of inflammation and further allergen exposure (Miller 2019).

Other diseases

Systemic allergic symptoms, sometimes severe, can occur after inadvertent ingestion of dust mites present in a food that has been colonized by mites, referred to as oral mite anaphylaxis. This was first reported in 1993, in a patient who ate a fried pastry made from flour that had been contaminated with D. farinae mites (Erben 1993). Subsequently, multiple cases of systemic allergy have been reported in mite sensitized patients who ate a variety of foods made with mite-contaminated foods including pancakes (Wen 2005), wheat and corn flour (Blanco 1997, Guerra Bernd 2001), grits (Posthumus 2012) and pizza (Kymioni 2025). Storing any opened packages of baked goods mixes, grains, or flour in a refrigerator will prevent the growth of mite populations.

Diagnostic Relevance

In vitro diagnostics

Mite allergy diagnosis involves a physical examination and medical history review to identify associations between mite exposure and symptoms. Confirmation of Der p sensitization is achieved through in vitro specific IgE testing and skin prick testing. Specific IgE testing may be preferred over skin prick testing for individuals taking medications that could interfere with skin test results, such as certain antihistamines, or for those with skin conditions like dermatitis.

A systematic review and meta-analyses of eight studies involving 1,095 patients supported the use of Der p 1 and Der p 2 IgE as useful tools to aid in the diagnosis of Der p allergic rhinitis and/or allergic asthma, detecting sensitization in approximately 80-90% of patients who are allergic to house dust mites (Tian 2017).

Prevention and Therapy

Prevention strategies

Avoidance

The effects of house dust mite reduction and avoidance measures on asthma, rhinitis, and eczema, have been assessed in systematic reviews following the Cochran Review methodology and criteria. In the Cochrane avoidance review on asthma, several trials were included involving in total 1,421 participants (Zuiani 2020). The review on rhinitis included 9 randomized controlled trials involving 501 participants (Sheikh 2010) and for eczema, 7 randomized controlled studies were included in the final review (Nankervis 2015).

Prevention of sensitization

Current Cochrane review evidence does not strongly support the effectiveness of avoidance measures in preventing sensitization to house dust mites. Zuiani (2020) reports that some studies have shown significant reductions in asthma exacerbations and symptoms with multi-faceted allergen avoidance approaches. However, these findings are more related to symptom reduction rather than the prevention of sensitization. Similarly, Sheikh (2010) concluded that while acaricides and extensive bedroom-based environmental control programs might reduce symptoms of allergic rhinitis, there is no strong evidence to support their effectiveness in preventing sensitization. Nankervis (2015) also reported that there is no clear evidence that house dust mite reduction and avoidance measures can prevent sensitization to house dust mites. However, the Nankervis 2015 review indicates that trials examining this question have been small and of low quality, making it difficult to draw definitive conclusions.

Reduction of allergic symptoms

In Zuiani (2020) several studies are reported to have shown significant reductions in asthma exacerbations, symptoms and acute health care visits after multi-faceted avoidance approaches targeting multiple allergens, including house dust mites. Effective strategies for allergen avoidance, particularly for house dust mites, include using mite-impermeable bedding covers, vacuum cleaners with HEPA filters, extensive bedroom-based environmental control programs, education on allergen avoidance and smoke exposure reduction, and combining physical barriers, acaricides, laundry services, and tailored education. Overall, a multi-faceted set of measures tailored to the patient's characteristics and home exposures was recommended to achieve the greatest reduction in allergen exposure and improving asthma symptoms.

The evidence supporting the effectiveness of house dust mite avoidance measures in managing perennial allergic rhinitis is limited (Sheikh 2010). Some studies indicate that acaricides and comprehensive bedroom-based environmental control programs may alleviate rhinitis symptoms. However, the Cochrane review highlights the need for more high-quality research to confirm these findings and provide definitive recommendations for the use of house dust mite reduction and avoidance measures in managing perennial allergic rhinitis.

The Cochrane evidence regarding the effectiveness of house dust mite reduction and avoidance measures in managing eczema was found limited and inconclusive (Nankervis 2015). Seven randomized controlled trials involving 324 adults and children with eczema were reviewed, including interventions like mattress and bedding covers, high-quality vacuuming, and mite-killing sprays. The trials did not provide sufficient evidence to recommend any specific measures, with no significant clinical benefit observed. The Cochrane review highlights the need for high-quality, long-term trials of simple interventions to assess the effectiveness of house dust allergen reduction and avoidance in managing eczema.

Allergen immunotherapy

Specific allergen immunotherapy (AIT) is a treatment option for house dust allergic patients with allergic rhinitis and allergic asthma. AIT is available in two main forms: subcutaneous immunotherapy (SCIT) administered via injections and sublingual immunotherapy (SLIT) taken under the tongue (Muraro 2018, Creticos 2024).

A recent real-world evidence study involving 7,260 patients with house dust mite AIT prescriptions and 21,780 control patients demonstrated that subcutaneous AIT reduces the need for medication to treat allergic rhinitis and allergic asthma. Additionally, it was found to delay the onset of asthma medication in patients with allergic rhinitis (Mösges 2024).

In the past decade, sublingual AIT tablets targeting house dust mite allergies have been developed and received regulatory approvals (Creticos 2021). These AIT tablets have demonstrated efficacy and safety in treating house dust mite induced allergic rhinitis in adults (Klimek 2016, Demoly 2021) and children (Sasamoto 2024), as well as adult asthma (Canonica 2016).

A systematic review including 23 randomized controlled trials with 1, 957 patients across 13 countries evaluated the effectiveness of sublingual and subcutaneous AIT for atopic dermatitis (AD). The findings suggest that AIT likely improves AD severity, itch, and sleep disturbance, with moderate-to-high certainty evidence for several outcomes. SCIT was associated with a modest increase in adverse events, while SLIT had fewer side effects. The review highlights the potential benefits of AIT for long-term AD control and calls for further research to optimize treatment protocols and understand long-term impacts (Yepes-Nuñez 2023).

Component-resolved diagnosis (CRD) using major allergens Der p 1 and Der p 2 may allow the identification of those patients who are best suited for house dust mite AIT immunotherapy (Pittner 2004) and a diagnostic algorithm integrating house dust mite allergenic molecules has been developed (Dramburg 2023).

Specific IgG4 to induced by house dust mite AIT can be useful to confirm successful immunological stimulation against Der p molecules (Zhao 2016) and delivery of AIT earlier in life may be associated with a greater increase in Der p specific IgG4 (Lai 2013). However, there is currently no firm clinical evidence that levels of specific IgG4 can predict or serve as biomarker for clinical efficacy in individual patients receiving AIT (Agache 2019).

Molecular Aspects         

The proteomes of house dust mites have been characterized identifying Der p specific proteins and potential allergens (Waldron 2019).

Allergenic molecules                                                                                                                                                          

To date, a total of 35 allergens for D. pteronyssinus have been identified and formally named by the WHO/IUIS Allergen Nomenclature Sub-Committee, see table 1.

Der p 1 and Der p 2 are major allergens in D pteronyssinus. The sensitization pattern in a total of 1,302 Dermatophagoides-allergic patients from Europe (466 adults and 423 children), Canada (350 adults), USA (35 adults) and Japan (28 adults) showed that >70% and >80% of patients were sensitized to house dust mite group 1 and group 2 allergens, respectively, from D. pteronyssinus and/or D. Farinae species (Batard 2016).

Furthermore, 20–47% of patients also had IgE to mite allergens from groups 4, 5, 7, 13, 15, 21, and 23. All patients had IgE to allergens present in mite bodies and faecal particles (Batard 2016).

Der p 1 is a 25 kDa glycoprotein allergen with cysteine protease activity, belonging to the papain family. The molecular structures of recombinant Der p 1 with its propeptide (Meno 2005) and a fully mature form of Der p 1 have been reported (de Halleux 2006). Der p 1 and Der f 1 share 81% amino acid sequence identity and similar three-dimensional structures (Chruszcz 2009) leading to IgE cross-reactivity.

Der p 2 is a heat and pH stable protein of 14 kDa, belonging to the NPC2 cholesterol-binding protein family. The molecular structures of recombinant Der p 2 (Derewenda 2002) and Der f 2 (Johannessen 2005) reveal that these allergens share highly similar three-dimensional structures leading to the high degree of IgE cross-reactivity between Der p 2 and Der f 2 (Yasueda 1989).

Sensitization to mites often starts at an early age and early sensitization to Der p 1, Der p 2 and Der p 23 have been found associated with asthma development (Posa 2017). Asthmatic atopic patients are also reported to be sensitized to a wider range of mite allergens than atopic patients without asthma and have higher levels of IgE specific for each allergen (Resch 2015).

Table 1. Current List of Dermatophagoides pteronyssinus allergens from WHO/IUIS Allergen Nomenclature Sub-Committee.

Molecular spreading

A study which followed a large cohort of children and tested for IgE to D. pteronyssinus extract and 12 individual allergens at regular intervals found that at age 20 years, the most frequent IgE specificity was for Der p 2, Der p 1, and Der p 23 (group A molecules; prevalence, >40%), followed by Der p 5, Der p 7, Der p 4, and Der p 21 (group B molecules; prevalence, 15% to 30%) and Der p 11, Der p 18, clone 16, Der p 14, and Der p 15 (group C molecules; prevalence, <10%).  The IgE response specificity started almost invariably with group A molecules and broadened sequentially first to group B and finally to group C molecules. A broader polymolecular IgE sensitization pattern was associated with early onset of IgE sensitization, parental hay fever, and higher exposure to mites. Individuals with the broadest IgE sensitization stage (i.e. ABC) had a significantly higher risk of mite-related allergic rhinitis and asthma than unsensitized participants. The presence of IgE to Der p 1 or Der p 23 at age 5 years or less predicted asthma at school age (Posa 2017).

Cross-reactivity

Studies have demonstrated almost complete IgE cross-reactivity between extracts of Der p and Der f and partial or low cross-reactivity between Der p and storage mites Lepidoglyphus destructor, Glycyphagus domesticus, Tyrophagus putrescentiae, Acarus siro and Blomia tropicalis (Pittner 2004, Zhang 2012). The group 1 and group 2 major allergens of Der p of Der f show high degree of IgE cross-reactivity.

Cross-reactivity also exists among allergens in dust mites and related arthropods including crustaceans (shrimp, crab, and lobster) and insects (cockroach, grasshopper), as well as members of the mollusk phylum (snails, clams, oysters, and squid). A pan-allergen responsible for these IgE cross-reactions to invertebrates is the muscle protein tropomyosin (Reese 1999, Sidenius 2001). In D. pteronyssinus mites, tropomyosin is represented by Der p 10 which shares sequence homology with shrimp tropomyosin Pen a 1, American cockroach tropomyosin Per a 7, and lobster tropomyosin Hom a 1 (Ayuso 2002). However, it is likely that tropomyosin is not the only relevant cross-reacting allergen, as there exist dust mite sensitive patients with shrimp allergy but not snail allergy, or with snail allergy but not shrimp allergy ​(Bessot 2010).

Explained Results

Allergen information

House dust mite Der p is an important indoor source of allergens, thriving in humid environments, beds and carpets. Allergens are present on mite fecal and body particles. Der p 1 and Der p 2 are the major allergens of Der p. Close to forty Der p allergens have been characterized.

Clinical relevance

Specific IgE to Der p is associated with allergic rhinitis, asthma, atopic dermatitis, and less frequently with symptoms following the intake of food contaminated by mites.

Cross reactivity

Extensive IgE cross-reactivity exists between extracts of Der p and Der f and partial or low cross-reactivity between Der p and storage mites. Cross-reactivity also exists among allergens in dust mites and related arthropods including crustaceans (shrimp, crab, and lobster) and insects (cockroach, grasshopper), as well as members of the mollusk phylum (snails, clams, oysters, and squid.

Compiled by: Dr. Christian Fischer, October 2020.

Last reviewed by Dr. Michael Spangfort, September 2025