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PubMed1983

IgE-mediated occupational allergy to a spider mite.

Two patients who suffered from allergic rhinitis, conjunctivitis and contact urticaria caused by the two-spotted spider mite (Tetranychus urticae, Koch) are described. Both patients worked in a greenhouse where they came in contact with both spider mites and predator mites living on bean leaves. Prick, Prausnitz-Küstner and RAST tests indicated type I allergy to spider mite but not to predator mite. Both patients had a high level (RAST score 4) of spider-mite-specific IgE in their sera. Radioallergosorbent test (RAST) inhibition studies revealed no cross-reactivity between spider mite and house dust mite allergens. These results show that spider mites, which are herbivorous mites found in nature, in greenhouses and even in homes, can cause IgE-mediated allergy in man.

Adult↗
PubMed1993

Mite fauna, Der p I, Der f I and Blomia tropicalis allergen levels in a tropical environment.

Fifty dust samples were collected from the mattresses and bedroom floors of 25 subjects with allergic asthma in Cartagena, Colombia, in order to identify house dust mites and quantitate Der p I, Der f I and Blomia tropicalis allergens. The geometric mean of the total mite density per gram of dust was 418 (range, 40-2280). Twenty-two samples (44%) had more than 500 mites and four, less than 100. B. tropicalis and Dermatophagoides pteronyssinus were found in 96% and 90% of the samples, accounting for 40.1% and 35.7% of the total mites, respectively. Cheyletus malaccensis, Chortoglyphus arcuatus, Pyroglyphus africanus, Oribatids, Grallacheles bakeri, Tarsonemus spp., Suidasia spp., Dermatophagoides farinae and unidentified mites accounted for the rest. The geometric mean of the total mites/gram of dust in mattresses (563.9) was significantly higher than in floor dust (309.1), P < 0.01. Allergen concentrations and mite numbers were analysed by Spearman rank correlations: B. tropicalis mites vs B. tropicalis allergen, r = 0.54, P < 0.001; D. pteronyssinus mites vs Der p I, r = 0.52, P < 0.001. A negative correlation was obtained between B. tropicalis mites and Der p I. Allergens derived from B. tropicalis and other domestic mite species may play an important role in sensitization and allergic symptoms in Cartagena, Colombia.

Allergens↗
PubMed1997

Domestic mites from an acarologic perspective.

Knowledge of the taxonomic, physiologic, biologic, and ecologic characteristics of allergenic domestic mites contributes to the understanding of the causation of many cases of allergic asthma, and to the measures to be taken to control excessive mite occurrence in homes. Domestic mites, i.e., the combined group of storage mites living in the home environment and of pyroglyphid house-dust mites, belong to the subclass of the acari. This comprises also many other mites of medical and economic importance, together with thousands of free-living mites. Because of some species-specific properties of their allergenic products, it is important that the producing mite is always correctly identified. In spite of their small size (approx. 0.5 mm), domestic mites have well-developed and elaborate systems of respiration, digestion, and water balance, enabling them to live and survive in the various habitats of the home environment. Knowledge of the effects of the various and changing ecologic conditions in the home environment is helpful in developing strategies to prevent the establishment and growth of large populations of allergenic domestic mites.

Animals↗
PubMed2005

IgE-sensitization to predatory mites and respiratory symptoms in Swedish greenhouse workers.

BACKGROUND: Predatory mites are used as biological pesticides worldwide for control of spider mites and other pests in greenhouses. The aim of this study was to evaluate the impact of occupational exposure to Phytoseiulus persimilis and Hypoaspis miles on IgE sensitization among a large group of Swedish greenhouse workers and to examine the relationship between exposure and allergic asthma and rhinoconjunctivitis. METHODS: A total of 96 greenhouse workers from the southern part of Sweden, who were using the predatory mites for control of pests, were investigated with a questionnaire and a medical examination including lung function test. Blood samples were taken to test for allergen-specific IgE antibodies to Phytoseiulus persimilis and Hypoaspis miles as well as to Tetranychus urticae, Dermatophagoides pteronyssinus/farinae and Tyrophagus putrescentiae. RESULTS: Seventeen of the 96 workers were positive in ImmunoCAP to predatory mites: 17 to P. persimilis (17.7%) and 14 to H. miles (14.6%). Subjects sensitized to predatory mites were significantly more often atopic (13/17), defined as a positive Phadiatop, than those who lacked IgE against these mite species (17/79) (P <0.01). IgE antibodies to the red spider mite T. urticae were present among 23 subjects. Thirty-five of the investigated subjects displayed a positive ImmunoCAP to at least one of the investigated mite species. Furthermore, sensitization to any of the mites tested was significantly associated with asthma (OR=9.3) and rhinoconjunctivitis (OR=4.3). CONCLUSIONS: IgE sensitization to predatory mites, P. persimilis and H. miles, is common among greenhouse workers. The findings stress the importance of improved allergen avoidance in greenhouse environments.

Adult↗
PubMed1998

Experimental monkey model sensitized with mite antigen.

BACKGROUND: Monkeys are considered to have an immune system very similar to that of humans, as compared with mice, rats, and guinea pigs. Although primate allergic models to several pollen allergens have been developed, no model of house dust mite allergy has been reported. In this study, we attempted to induce type I allergy to mite allergens in rhesus monkeys. METHODS: Six rhesus monkeys were immunized subcutaneously with crude mite extract adsorbed on aluminum hydroxide for 4 months. Then 5 monkeys positive for IgE production to mite extract were further immunized subcutaneously and conjunctivally with recombinant Der f 2 (rDer f 2). The status of sensitization to mite extract and rDer f 2 in monkeys was examined before and after the immunization. Plasma antigen-specific IgE and IgG levels, cutaneous reaction, and histamine release from peripheral blood leukocytes were measured. After conjunctival immunization, immediate conjunctivitis and leukocyte influx into conjunctiva after rDer f 2 challenge were examined. RESULTS: After immunization with crude mite extract, 5 of 6 sensitized monkeys showed IgE response to the mite, and 4 out of 5 rDer f 2-sensitized monkeys exhibited IgE production to rDer f 2. Three monkeys sensitized with rDer f 2 showed immediate conjunctivitis and conjunctival eosinophilia after applying rDer f 2 to their eyes. Sensitized animals also showed IgG response to mite antigens. CONCLUSION: Four rhesus monkeys were positive for IgE production and allergic reactions to both mite extract and rDer f 2. These monkeys could represent a useful model for studying the development and regulation of house dust mite allergy.

Allergens↗
PubMed2006

Are soil mite assemblages structured by the identity of native and invasive alien grasses?

Associations between plants and animals in aboveground communities are often predictable and specific. This has been exploited for the purposes of estimating the diversity of animal species based on the diversity of plant species. The introduction of invasive alien plants into an ecosystem can result in dramatic changes in both the native plant and animal assemblages. Few data exist at the species level to determine whether belowground animal assemblages share the same degree of association to plants. The hypotheses that soil mites (Acari) form assemblages specifically associated with different native grass species in an unmanipulated natural ecosystem and that invasive alien grasses will impact soil mite assemblage composition in this setting were tested. Soil mites sampled beneath five native and two invasive alien species of grasses at the Konza Prairie Biological Station, Kansas, USA, were similarly abundant, species rich, diverse, and taxonomically distinct. No mite species had affinities for a specific grass species. There was no evidence from analysis of similarity, canonical correspondence analysis, or a nonparametric assemblage analysis that the assemblage composition of soil mites was specific to grass species. Results suggest that soil mite assemblages were more related to characteristics of the plant assemblage as a whole or prevailing soil conditions. The most recent invasive alien grass did not support a successionally younger mite fauna, based on the ratio of mesostigmatid to oribatid mites, and neither of the two invasive grasses influenced mite assemblage structure, possibly because they had not yet substantially altered the soil environment. Our results suggest that extrapolations of soil mite diversity based on assumptions of plant specificity would be invalid.

Animals↗
PubMedDate not supplied

Sensitization to different mite species in German farmers: clinical aspects.

Various mite species referred to collectively as house dust and storage mites are recognized worldwide as a cause of allergic airway disease. Our study aimed to investigate the frequency of sensitization and potential importance of mite species in farmers using a broad mite spectrum. A total of 86 German farmers with rhinitis and/or asthma were studied by skin prick testing and/or enzyme allergosorbent test (EAST) with the following mites: Blomia tjibodas, Blomia tropicalis, Blomia kulagini, Glycyphagus domesticus, Thyreophagus entomophagus, Euroglyphus maynei, Chortoglyphus arcuatus, Dermatophagoides pteronyssinus, Dermatophagoides farinae, Acarus siro, Lepidoglyphus destructor, Tyrophagus putrescentiae, Acarus farris and Cheyletus eruditus. Sensitization to at least one mite species was detected in 51 patients (59%) by skin prick testing, and in 31 patients (36%) by EAST. The most frequent sensitizations determined by skin tests were found for the three Blomia species, E. maynei and G. domesticus. Twelve patients (14%) gave a positive EAST with the predator mite C. eruditus. A total of 22 patients gave positive EAST results with the Dermatophagoides species. We were able to document sensitization to C. arcuatus, E. maynei and T. entomophagus for the first time in Germany. A considerable proportion of the German farmers tested were sensitized to storage mites. The allergological potential of various mite species has been recognized, some for the first time. It was concluded that B. tjibodas, G. domesticus, C. arcuatus and C. eruditus in particular should be included in an allergy diagnosis. Further investigations into the clinical relevance of the sensitizations and possible cross-reactivity between the mite species are necessary.

Adult↗
PubMed2001

[Mites and their allergens: identification and extermination methods].

Mite allergens are the main allergens in indoor environment. Using different means of assessing exposure to house dust mites (Acarex-test, major allergen (Der p 1 + Der f 1, Der p 2 + Der f 2), content measured by ELISA) has allowed better identification of mite reservoirs and allergens in patients' homes. House dust mite control measures are based on the knowledge of factors contributing to mite development, especially indoor relative humidity. Mite allergen avoidance strategies include 3 different methods: avoidance of mite producing allergens, elimination of mite reservoirs, especially textile reservoirs, dwellings designed so as to inhibit mite proliferation. Only controlled trials can estimate patients' compliance with proposed avoidance measures. Avoidance protocols should be adjusted to each individual by medical indoor environment counselors in order to optimize mite allergen reduction.

Allergens↗
PubMed2003

[Inhibition of antisense-endothelin converting enzyme RNA on interleukin-5 released from dust mite-challenged peripheral blood mononuclear cells in patients with allergic asthma].

OBJECTIVE: To investigate the effect of antisense endothelin converting enzyme (ECE) RNA on levels of cytokines released from CD(4)(+) lymphocytes in patients with allergic diseases responsive to house dust mites. METHODS: Peripheral blood mononuclear cells (PBMCs) were separated from 21 patients who were sensitive to dust mites. PBMCs from those patients were divided into two groups. No stimulation group (A group) induded A(1) group (anti-ECE epithelial cells + PBMCs) and A(2) group (control cells + PBMCs). Stimulation group (B group) included B(1) group (anti-ECE epithelial cells + PBMCs + dust mites extract) and B(2) group (control cells + PBMCs + dust mites extract). House dust mite extract (20 microg/ml) was added to the culture of stimulation group as described above. After 72 hours, supernatants from both groups were collected and the levels of IL-5 and IFN-ggr; released into the supernatants were detected by enzyme-linked immunoabsorbent assay. RESULTS: IL-5 levels were increased significantly after treatment with dust mite in twelve of 21 cases. No significant differences of IL-5 were found between the groups of A(1)[(6.0 +/- 1.3) x 10(-9) g/L] and A(2) [(7.5 +/- 1.1) x 10(-9) g/L] before house dust mite stimulation in the 12 cases (P > 0.05), and no significant differences in IFN-ggr; were found between the groups of A(1) [(63 +/- 26) x 10(-9) g/L] and A(2) [(70 +/- 52) x 10(-9) g/L] before house dust mite stimulation (P > 0.05). IL-5 level was increased in both groups after stimulation but it was significantly lower in the B(1) group [(8.2 +/- 1.6) x 10(-9) g/L] than that in the B(2) [(12.0 +/- 1.8) x 10(-9) g/L] (P = 0.047). It seemed that increased IFN-ggr; level after stimulation was higher in B(2) [(153 +/- 71) x 10(-9) g/L] than that in the B(1) group (100 +/- 41) x 10(-9) g/L], but there was no statistic significance (P > 0.05). In addition, our results also showed that the release of IL-5 was significantly increased in those cases with asthma, or asthma plus allergic rhinitis after dust mites stimulation [(44 +/- 15)%] compared with that in those with urticaria [(7 +/- 4)%] (P = 0.047). CONCLUSIONS: Antisense-ECE downregulated the IL-5 secretion from Th2 lymphocytes in patients with allergic asthma after being challenged with dust mites. It is indicated that ET-1 is an important cytokine involved with allergic airway inflammation. Antisense-ECE RNA management in airways may be of value in treating allergic asthma.

Adult↗
PubMed2006

Exposure of workers to mites in Finnish groceries.

We assessed the mite exposure of workers in Finnish groceries by collecting samples of settled dust in 5 different grocerys. Mites were counted and identified microscopically. Mite allergen (Der p 1 and Der f 1) content of dust was analyzed with 2-site ELISA. Mites were found in 20-100 % of the samples, both from storage and salesrooms. Seven samples (8 %) contained more than 100 mites per gram dust and 3 additional samples (6 %) more than 500 mites per gram dust, the suggested limits for mite sensitization and acute allergic symptoms, respectively. Most of the mites were storage mites belonging to Astigmata (Acaridae, Glycyphagidae) or Prostigmata (tarsonemids). House dust mites were found only occasionally. One dust sample out of 15 contained Der p 1, and none contained Der f 1.

Acaridae↗
PubMed1989

Pyroglyphid mites in the High Tatras sanatoria.

1. In our work we studied the problematics of house dust fauna in the sanatoria and institutes of the Tatra region, regarding especially the incidence of mites of the family Pyroglyphidae that are considered for the major source of house dust allergen. 2. In eleven places of different altitude in this region, there were in 1982 chosen 13 localities--sanatoria and institutes. Here, once quarterly, were collected house dust samples from beds and floors. 3. In the Locality 1 Helios, Strbské Pleso, the house dust samples were collected in 1976, once in two months, in 1979 once in three months, and in 1982 once quarterly. Here, the involvement of the new--opened sanatorium by house dust mites was studied. 4. House dust samples in the studied localities were collected using the electric vacuum cleaner into the changeable paper bags. The samples were examined by flotation due to Spieksma (1970) and due to the modification of Spieksma's methodics elaborated by Samsinák et al. (1974). 5. The found house dust mites--pyroglyphids were evaluated due to Bronswijk and Sinha (1971) and due to the modification of their methodics elaborated by Samsinák et al. (1974). The classification due to Wharton (1976) was used as well. 6. In every studied locality, in house dust collected from floors and beds, there were identified mites of the family Pyroglyphidae, considered for the major source of house dust allergen. 7. Mites of the family Pyroglyphidae were represented by the genera Dermatophagoides and Euroglyphus, and by the species Dermatophagoides pteronyssinus, Dermatophagoides farinae, and Euroglyphus maynei. There were found as well the nymphal instars of the genus Dermatophagoides, in this development degree it is very complicated to determine precisely the species--and that is why the term Dermatophagoides sp. nymphal instar is used. 8. In 1982 there were in the chosen localities collected 764 house dust samples from beds and 20 samples from floors, 186 of them (23.7%) were negative--without any mites. In the positive samples there were identified 1794 arthropods, 1776 were mites and 18 were Psocopterae. Of the total mite number 1263 (71.1%) were mites of the family Pyroglyphidae. 9. The other mite families were represented by 513 pieces, i.e. 28.6% of the total arthropod number. 10. In the studied localities there were identified three species of the family Pyroglyphidae and 15 species of other families, the representatives of the families Ereinaetidae, Tetranychidae (not determined preciselier), and Oribatei.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

[Immunochemical quantification of the airborne mite allergens].

We collected airborne particle from indoor air by using a high-volume air sampler, and measured mite allergens in the air-filter extract by use of RAST inhibition assay. The results obtained were as follows: 1) The assay revealed the presence of house dust mite allergen in the indoor air varying from 690 to 129000 pg/m3. 2) In apartments, seasonal fluctuations of house dust mite allergen in the indoor air demonstrated a peak in autumn (September and October), and showed a tendency to increase in spring. In our outpatient clinic, the quantity of house dust mite allergen in the indoor air varied from 690 to 5670 pg/m3, while there were few mites on the floor, and showed a tendency to increase in winter. 3) There was a significant correlation between the quantity of house dust mite allergen in the indoor air and the number of mite in house dust (r = 0.535, p less than 0.01). 4) The amount of D.f. allergen in the indoor air was significantly decreased by using air cleaners (p less than 0.005). These results showed that the quantification of house dust mite allergen was useful from the clinical point of view as a parameter of mite pollution indoors, and it was important for asthmatics to live in clean environment, and to decrease the number of mites in house dust.

Allergens↗
PubMed1987

Storage mites in the work environment of farmers.

Occurrence of storage mites was studied in cow houses and hay stores on 19 farms, most of which were located in eastern Finland. On two farms we did a monthly follow-up. Mites were extracted from hay by sieving, using the so-called "water trap" and for longitudinal analysis, with a warm extractor. The mites isolated in the water trap were identified under a microscope. Contrary to previous Finnish findings, there apparently were more mites in cow houses than in hay stores. In cow houses there were an average of 1,650 mites per gram of dust and in hay stores about 1,100 mites per gram of dust. Acarus siro was most abundant in cow houses (67% of all the mites found in cow houses) and more than 1,000 mites/g of sample material. The second most numerous was Tydeus spp. (178 mites/g of sample material). After that, Lepidoglyphus destructor, Tyrophagus longior, Glycyphagus domesticus occurred in about equal numbers. In hay stores Tydeus spp. was slightly more common (341 mites/g of sample material) than Acarus siro (317 mites/g of sample material). Lepidoglyphus destructor (64 mites/g of sample material), Glycyphagus domesticus (60 mites/g of sample material) and Mesostigmata (57 mites/g of dust) occurred in about equal numbers. According to the analysis based on one farm the number of mites in hay stores decreased considerably from September to February. Based on four measurements in the cow house of another farm, however, no steady trend of longitudinal variation could be found. Mites were most abundant at the beginning of January. There were few or no mites in bales of dry and unmoulded hay.

Agricultural Workers' Diseases↗
PubMed1995

[Allergens from Dermatophagoides dust mites: origin, antigenic and structural characteristics, and therapeutic agents].

Micromites (genus Dermatophagoides) are the major source of allergens in house dust. Four homologous classes of major allergens have been isolated from extracts of D. pteronyssinus and D. farinae mites. According to current theories, all major mite allergens are proteins of gastrointestinal origin. Group I mite allergens, Der pI and Der fI, are thermolabile glycoproteins with M(r) of 25 kDa. A comparison of primary structure of these proteins reveals a 30% homology with cathepsins B and H, papain and actinidine. Analysis of enzymatic activities reveals that group I allergens are proteolytic enzymes related to the class of cysteine proteinases. With regard to antigenic composition, Der pI and Der fI have three common and two species-specific epitopes. The amino acid sequence of the major allergenic determinant for Der pI has been established. Group II mite allergens, Der pII and Der fII, are single-chain thermostable proteins with M(r) of 10-14 kDa and are said to bear many common features with the lysozyme. Group III mite allergens are analogous to trypsin. A 50% homology of amino acid sequences of Der pIII and Der fIII to those of vertebrate and invertebrate serine proteinases has been found. To the fourth group of major mite allergens one may relate mite amylase (M(r) = 56-60 kDa). A high degree of homology has been established between group IV allergens and mammalian alpha-amylase. Mite allergens of all groups induce the production of specific IgE antibodies in human organism. The use of purified allergens increases the efficiency of diagnosis and treatment of mite-induced allergoses. Modified forms of mite allergens (allergoids, allergens adsorbed on carriers, liposome preparations, etc.) are helpful tools in specific immunotherapy.

Allergens↗
PubMedDate not supplied

Study of the sensitization to storage mites in a pediatric population in Barcelona.

We performed the following study in order to determine the prevalence and characteristics of sensitization to storage mites in children mostly from the city of Barcelona. All children over 3 years of age attending our unit for the first time due to respiratory problems were given cutaneous tests using the prick test for the house dust mites Dermatophagoides pteronyssinus and D. farinae, and the storage mites Acarus siro, Lepidoglyphus destructor and Tyrophagus putrescentiae. We carried out a RAST and conjunctival test when it was considered appropriate. Of a total of 356 children studied, 39 showed cutaneous sensitization to storage mites, which represented 11% of the population studied, and 20% of the total sensitized to mites. However, only 3 of these children were only sensitized to storage mites, the remaining 36 (92%) also showing sensitization to house dust mites. Of the storage mites studied, L. destructor was the most significant. A history of immunotherapy to mites was associated with a greater percentage of positive cutaneous tests to storage mites, although this was not the case with the RAST test.

Animals↗
PubMed1997

Mite allergy is associated with a specific profile of IgG epitopes recognized on antigen p1 of Dermatophagoides pteronyssinus.

BACKGROUND: Immune response to inhaled antigens differs in allergic patients and healthy individuals, mostly in the quality of T cell help provided (i.e. Th2 or Th1 dominant subset). However, while different in many functional aspects, both groups of T cells shared the capacity to support the synthesis of antigen-specific immunoglobulin G (IgG) antibodies detected in different amounts in the serum of atopic and healthy individuals. OBJECTIVE: The present study investigates whether these IgG responses display similar or different epitopic dominance in the mite sensitization model. METHODS: Antibody specificity was evaluated by comparing the IgG binding to native Der p1 (nDer p1) and its products of pepsin hydrolysis (dDer p1) in 56 mite-allergic patients and 148 healthy individuals, including 24 mite-sensitized individuals in a solid enzyme linked immunosorbent assay (ELISA). Antibody specificity was also studied in competitive ELISA using streptavidin biotin technology. RESULTS: Mite-allergic sera showed a higher degree of binding to nDer p1 than to dDer p1, whereas control sera and mite-sensitized sera bound at a similar level to the two forms of the antigen. Allergic sera and control sera, including mite-sensitized sera, showed distinct capacities to prevent the binding to nDer p1 of pooled IgG from each group as well as murine monoclonal antibodies specific to Der p1. CONCLUSION: The IgG response to Der p1 of mite-allergic patients differs from that of healthy controls and mite-sensitized subjects, not only in its increased titres but also in its consistant pattern of modified specificity, displaying a marked preference for conformational epitopes. Cross-competition experiments confirm the clinically associated, restricted specificity, allowing almost complete discrimination between groups, particularly between mite-sensitized and mite-allergic subjects, which is currently impossible with routinely available assays.

Adult↗
PubMed2006

Prevalence of serum IgE to storage mites in a southwestern Ohio population.

BACKGROUND: Storage mites of the families Chortoglyphidae, Glycyphagidae, Echimyopodidae, and Acaridae are commonly found in agricultural and nonagricultural environments. The prevalence of sensitization to these storage mites in the general population in the United States is unknown. OBJECTIVE: To determine the prevalence of serum IgE to the storage mites Lepidoglyphus destructor and Acarus siro and to evaluate the degree of co-sensitization to various other astigmatid mites in a population in southwestern Ohio. METHODS: Serum samples from 600 people randomly selected from a 1-day submission of approximately 3,000 samples to a clinical diagnostic laboratory were screened for IgE to allergens of L destructor and A siro. Proteins in the extracts of each mite were electrophoretically separated, transferred to membranes, and incubated in the serum samples, and the slot blots were probed for IgE binding using radiolabeled anti-human IgE and autoradiography. RESULTS: Thirty-two (5.3%) of the 600 serum samples screened had IgE to allergens from at least 1 of the 2 mite species; 14 (2.3%) and 20 (3.3%) had serum IgE to proteins of the mites A siro and L destructor, respectively. Additional analysis revealed that most serum samples also had IgE that bound to proteins in extracts prepared from a variety of other astigmatid mite species, but IgE binding profiles suggested little cross-reactivity. CONCLUSIONS: Sensitization to the mites L destructor and A siro is significant in this region of southwestern Ohio. Further studies are needed to determine the importance of these and other storage mites in occupationally exposed and urban populations of the United States.

Acaridae↗
PubMed2003

Laboratory assessment of the efficiency of encasing materials against house dust mites and their allergens.

BACKGROUND: The current recommendation to reduce mite allergen exposure for mite-sensitive individuals is to use allergen-impermeable bed coverings. As these covers are made of various kinds of materials, they vary in quality. The objective of this study was to investigate the efficiency of different covering materials against house dust mites and their allergens in vitro. METHODS: Four types of materials including (1) plastic cover, (2) polyurethane-coated cover, (3) non-woven covers, (4) tightly woven microfiber covers and a regular cotton bed sheet (as a control) were evaluated using three methods: (i) heat escape method, (ii) Siriraj chamber method and stereomicroscopy, scanning electron microscopy and (iii) enzyme-linked immunosorbent assay (ELISA). RESULTS: We found that there was a statistically significant difference in allergen permeability among four types of coverings (P < 0.001). In terms of the impermeability to mites and their allergens, plastic- and polyurethane-coated covers were observed to be the best, followed by non-woven, woven and cotton-based bed sheets. A regular cotton-based bed sheet allows a significant amount of leakage of mite allergens. Both woven and non-woven material are efficient barriers against mite allergen in terms of impermeability. However, with regard to mite colonization, non-woven covers have the drawback of mites being able to penetrate and colonize within the fabric fibers. Woven covers are therefore recommended because of their major advantages of not allowing the colonization of mites within the fabric, being easy to clean, and comfortable. CONCLUSION: The three assessment methods used in this study could be useful as a primary approach to evaluate the quality of covering materials in vitro using both pore size and ability to be colonized by mites on the materials as the key factors.

Allergens↗