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PubMed1990

Ecology of house dust mites in Oxfordshire.

In a survey of the mite fauna in 30 homes in Oxfordshire, Dermatophagoides pteronyssinus and Euroglyphus maynei were found to be the most abundant species but D. farinae was absent. Of a total of 14 parameters investigated for their influence on mite numbers, relative humidity was apparently the most important factor. Bedrooms with humidities above 64% contained significantly more mites in mattresses than those with lower humidities. Bedroom humidity and thus mattress mite numbers were apparently related and were influenced by the bedroom minimum temperature, the age of the house and the use of central heating. These trends were not seen in the numbers of mites found in living-room carpets. Atopic and non-atopic participants involved in this study did not differ significantly in the numbers of mites found in their homes.

Allergens↗
PubMed1990

The prevalence of allergic disease and IgE antibodies to house dust mite in schoolchildren in Taiwan.

The prevalence of positive specific IgE antibodies to house dust mites (Dermatophagoides pteronyssinus; D. farinae) was determined by enzyme-linked immunosorbent assay (ELISA) in 5097 (61%) volunteers of 8345 schoolchildren aged between 7 and 14 yr from two government schools. All of them filled out a questionnaire concerning allergic symptoms. Among them, 412 (8.1%) children showed a positive reaction to at least one of the two mite allergens, the range varying between 5.6 and 11.2% according to the child's age. Boys had higher prevalence of positive mite specific IgE than girls (9.8% vs. 6.4%, P less than 0.01), with the overall male to female ratio 1.5:1. The prevalence of bronchial asthma in boys and girls was 5.3% and 3.3% respectively. The positive mite specific IgE antibody in children with asthma and allergic rhinitis was 52% (103 of 198) and 28.7% (193 of 673) respectively. The mean levels of mite specific IgE were not significantly related to the age of onset and severity of asthmatic symptoms (P greater than 0.1), but were significantly different among subjects with current and past asthma (P less than 0.001). It is suggested that the mite-specific IgE may play a role in the pathogenesis of bronchial asthma in children.

Adolescent↗
PubMed1998

Microsatellite sequences are under-represented in two mite genomes.

Microsatellites are known to be a common feature of eukaryote genomes. Here we investigate the presence of microsatellite sequences in the genome of two mite species, Tetranychus urticae and Amblyseius fallacis, based on screening of both mite genomic libraries and Southern blots of these mites that we compare to two vertebrates. No signal with GT15 or a faint smear with CT10 were obtained in Southern analysis for the two mites, whereas both probes strongly bound with vertebrate DNA. Genomic libraries constructed in plasmid and lambda vectors were probed and only two CT microsatellites were isolated for T. urticae. Among eight trinucleotides probes tested, the strongest hybridization signal was detected for T. urticae with CAT and TGA probes. These two classes of repeats were also the most represented in genomic library screenings. However, only sequences with short numbers of units could be detected (<CAT4 or TGA9). Congruency of Southern analysis and screening of partial genomic libraries indicates an under-representation of microsatellite sequences in the two mite genomes. The potential of the scarce repetitive DNA isolated from mites to serve as population genetics markers is discussed on the basis of preliminary assessment of their polymorphism.

Animals↗
PubMed2006

House dust and forage mite allergens and their role in human and canine atopic dermatitis.

This article reviews the literature regarding the role of house dust and forage mite allergens in canine atopic dermatitis. The presence of immunoglobulin E (IgE) to these mites, especially to Dermatophagoides farinae, is common in both normal and atopic dogs. Exposure of dogs to the different mites is described both in the direct environment and in the coat of animals for house dust mites and in the food for forage mites. Allergens causing allergic disease in dogs seem to be different from those in humans. Dogs seem to react to high molecular weight allergens, compared to the low molecular weight group 1 and group 2 proteases that are commonly implicated in humans with atopic diseases. Despite numerous published studies dealing with this subject, a number of questions still need to be addressed to better understand the exact role of these mites in the pathogenesis of canine atopic dermatitis and to improve the quality of the allergens used in practice.

Allergens↗
PubMed1975

Precipitin to mite detected in asthmatic patients.

Mite antigen from dermatophagoides farinae was labelled with 125I, and used for detection of precipitin to mite antigen in sera from asthmatic patients allergic to mite and house dust. By double gel diffusion using this labelled antigen, it was found that 16 out of 37 sera formed precipitin bands which were detected by radioautography. Only one serum formed a precipitin band when non-labelled mite antigen was used in double gel diffusion. The main immunogenic component in mite extract migrated to the beta region in immunoelectrophoresis. The intensity of the precipitin line did not correlate with the relative concentration of IgE antibodies as determined by RAST. IgG antibodies to mite were detected by radioimmunoelectrophoresis in three out of 37 sera.

Allergens↗
PubMed1976

Clinical significance of the house dust mite (Dermatophagoides pteronyssinus) in asthmatic children in Japan.

Clinical studies were conducted to evaluate the role of the house dust mite. Dermatophagoides pteronyssinus, as an allergen in children's asthma in Japan. Skin testing and Prausnitz-Küstner type skin testing showed good correlations between the allergenicity of house dust and the mite. A positive Prausnitz-Küstner type skin reaction to house dust was neutralized by a mite extract. Radioallergosorbent test showed good correlation between house dust and the mite (r=0.687). The mite exhibited in vitro inhibition of radioallergosorbent test to house dust. The inhalation provocation test resulted in an acute respiratory attack in one of the patients. These results suggest that the house dust mite is an important allergen in asthmatic children in Japan.

Adolescent↗
PubMed1979

Tarsonemid mites in Danish house dust.

From a study of 98 typical Danish city apartments it was found that pyroglyphid and tarsonemid mites dominated the housedust acarofauna. Both groups of mites show a remarkable similarity in their occurrence and dependence on the microclimate. Room air humidities above 7 g water/kg dry air involved the highest densities. Below this limit only background contamination appeared. At least 14 distinct forms of tarsonemid mites were found, with Tarsonemus floricolus Can. & Fanz., 1876 as the dominating species. As tarsonemid mites were found regularly rather than occasionally, it is suggested that these mites may be responsible for at least a part of the cases of housedust allergy that cannot be ascribed to the content of Dermatophagoides mites in the housedust.

Allergens↗
PubMed1985

Allergy to storage mites or cow dander as a cause of rhinitis among Finnish dairy farmers.

The role of storage mites Acarus siro, Lepidoglyphus destructor, and Tyrophagus putrescentiae, compared with that of cow dander, as a cause of allergic rhinitis was studied by nasal challenges in a population of 106 non-smoking dairy farmers. Thirty-six of the subjects were challenged with storage mites alone, each with only one of the three species in consecutive order, 43 with cow dander alone, and 27 with both. Thus mite challenges were performed on 63 farmers and cow dander challenges on 70. Challenges with any one of the storage mite species were positive in 18% and with cow dander in 20% of farmers with allergic rhinitis. All challenges to asymptomatic farmers were negative. Five of the eight positive reactions to storage mites were due to Lepidoglyphus destructor, and three to Tyrophagus putrescentiae. Acarus siro was not responsible for any of the positive reactions. The results indicate that, among dairy farmers, storage mites are as common as cow dander as a cause of allergic occupational rhinitis.

Allergens↗
PubMed1993

Mite (Der p 1, Der f 1) and cat (Fel d 1) allergens in the homes of babies with a family history of allergy.

Carpet and floor dust samples were collected in four different seasons, from 39 Swedish homes of babies with a family history of allergy. House-dust mite (Der p 1, Der f 1) and cat (Fel d 1) allergen contents were determined by mab ELISA, and the levels were related to various environmental factors. Both mite and cat antigens were detected in 94% of the samples and in all homes, but the levels were low (Der p 1, range 15 ng-1944 ng/g fine dust; Der f 1, range 14 ng-264 ng/g of fine dust; Fel d 1, range 16 ng-3120 ng/g fine dust). Mite-allergen levels were significantly higher (P < 0.001) in floor dust than in carpets, and D. pteronyssinus predominated. In contrast, the levels of cat antigen were significantly (P < 0.05) higher in carpets than in floor dust. There was no clear relation between mite-allergen levels and type of house, except that the higher values were found in homes with dampness problems. Cat-allergen levels were higher than total mite-allergen content, and the highest levels were found in homes with a cat (P < 0.05). Rather high concentrations of cat allergen were also found in homes without a cat, which may explain why cat sensitization is so common in Sweden. As the prevalence of house-dust mite sensitivity is increasing in Swedish children, and as the individual patient threshold for eliciting symptoms varies, we suggest that sensitization may possibly occur at a lower exposure level than generally accepted as risk level for sensitization (2 micrograms/g dust).

Allergens↗
PubMed1996

Sensitization to Dermatophagoides siboney, Blomia tropicalis, and other domestic mites in asthmatic patients.

Mite species adapted to warm, humid climates are commonly found in house dust in the tropics. In Cuba, Dermatophagoides pteronyssinus, D. siboney, and Blomia tropicalis are the most common and abundant mite species in house dust. To investigate the pattern of sensitization of Cuban asthmatic patients to common mite species, we skin-prick-tested (SPT) 148 patients with a clinical history of asthma and possible mite allergy, and determined specific IgE antibodies against mite allergens (D. pteronyssinus, D. farinae, D. siboney, B. tropicalis, Acarus siro, Lepidoglyphus destructor, Tyrophagus putrescentiae, and Glycyphagus domesticus). The prevalence of positive SPT was high to D. siboney (88%), D. pteronyssinus (87%), A. siro (85%), B. tropicalis (85%), and D. farinae (83%). The largest skin reactions were obtained with D. siboney and B. tropicalis extracts. The skin test response to the D. siboney extract correlated to those of D. farinae, D. pteronyssinus, B. tropicalis, and A. siro. The highest IgE levels were found to Dermatophagoides species and B. tropicalis. IgE to D. siboney and B. tropicalis were found in 97% and 96% of the patients, respectively. The prevalence of specific IgE to the other mites studied varied from 46 to 65%. D. siboney and B. tropicalis are important sensitizers among asthmatic patients in Cuba.

Adolescent↗
PubMed1996

Indoor mite allergens in patients with respiratory allergy living in Porto, Portugal.

We investigated the levels of mite allergens (Der p 1, Der f 1, Der 2, and Lep d 1) in dust samples from the homes of 59 patients with asthma, 36 sensitized to house-dust mites (HDM) and 23 to grass pollen (controls), living in Porto, northern Portugal. The relationship between exposure and sensitization to HDM and the influence of housing conditions on mite-allergen levels were also evaluated. Der p 1 (median 9.2 micrograms/g) and Der 2 (4.6 micrograms/g) were the main allergens, while Der f 1 and Lep d 1 levels were always < 1 microgram/g dust and undetectable in 11% and 47% of samples, respectively. All HDM-sensitized asthmatics were exposed to Der p 1 levels > 2 micrograms/g and their homes contained significantly higher levels of Der p 1 (median 12.5 vs 6.4 micrograms/g; P = 0.008) and Der 2 (6.2 vs 3.0 micrograms/g; P = 0.004) when compared to the control group. A significant correlation was observed between the exposure to Der p 1 and the wheal area at skin testing with the Dermatophagoides pteronyssinus (Dp) extract (P = 0.01) as well as with serum specific IgE levels to Dp (P = 0.03). Patients with higher levels of serum specific IgE (> or = 17.5 HRU/ml) were also more frequently exposed to Der p 1 levels > or = 10 micrograms/g (P = 0.002). Old homes, presence of carpets, and signs of dampness were conditions associated with significantly higher levels of mite allergens. In conclusion, we found high levels of Der p 1 and Der 2 particularly in the homes of HDM-sensitized patients and we confirm the relationship between exposure and sensitization to HDM, assessed by both in vivo and in vitro methods. In additional to a favorable outdoor climate, we found in our region housing conditions propitious to mite growth, suggesting that specific geographic characteristics must also be taken into account for the correct planning of mite-avoidance measures.

Adolescent↗
PubMed1998

Environmental assessment of Dermatophagoides mite-allergen levels in Sweden should include Der m 1.

The major allergen of Dermatophagoides microceras, Der m 1, as well as the allergens of D. pteronyssinus and D. farinae, Der p 1 and Der f 1, were analyzed in the homes of 111 asthmatic children in three climatic regions in Sweden. The numbers and species of mites were determined by microscopy, and circulating IgE antibodies against mites were measured. Der f 1 was the predominant house-dust-mite (HDM) allergen, Der p 1 the least often found, and Der m 1 represented 31% of the allergen load. However, in the Linköping area, Der m 1 was the major HDM allergen (58%). Mite counts and allergen levels correlated well. Current exposure to HDM allergens at home was associated with the serum IgE antibody response to HDM in the children with no threshold level. Of the children with IgE antibodies against HDM, 67% reacted to all three mites. Mite sensitization rates were marginally increased (7%) by the addition of IgE analysis of D. microceras to the routine analysis of IgE antibodies against D. pteronyssinus and D. farinae. Thus, Der m 1 may be an important HDM allergen and should be considered when HDM exposure data are assessed in areas with a climate like that of Sweden.

Adolescent↗
PubMed1998

Distribution and abundance of dust mites within homes.

The distribution and abundance of dust mites can be modelled on three scales: the microhabitat scale (different habitats within homes), the macrohabitat scale (between homes), and the regional scale. This paper focuses on the first. Those parts of a home in which dust mite populations thrive will tend to be homogeneous in respect of key habitat suitability determinants. The more widespread such determinants, the greater the risk of high mite populations and allergen load. Habitat suitability determinants include an adequate textile substratum, optimal temperature and humidity, and food resources of appropriate quality, as well as other, currently unknown, requirements. Each determinant will have a characteristic distribution within any home, and they can be conceptualized as a series of overlays, or three-dimensional Venn diagrams, with the areas of overlap representing the most suitable sites for mite survival. That a population of dust mites is focused by constraining biotic and abiotic determinants means that spatial and temporal distribution and abundance are predictable, because the characteristics of the principal foci define optimal conditions for population growth. This concept, known as "focality", provides a framework for prediction of sites of high density of mite population and allergen exposure, as well as a basis for manipulating the microenvironment for control purposes.

Allergens↗
PubMed1998

Allergy to mites: relation to lung function and airway hyperresponsiveness.

Exposure to house-dust-mite allergens is an important cause of allergic reactions in sensitized patients. In community-based studies, sensitization to house-dust mites, as ascertained by a positive skin test or by an increased allergen-specific IgE level in serum, is associated with both diminished lung function and enhanced airway hyperresponsiveness. Sensitization to house-dust mites is an independent risk factor for the development of asthma, especially in areas which favor the growth of house-dust mites. In studies with asthmatic patients, however, the relationship between sensitization to mites and lung function or airway hyperresponsiveness is less clear. The selection of asthmatic individuals (with sensitization to other inhalant allergens) and the use of medication such as inhaled steroids may interfere with the demonstration of a possible association between mite allergy and lung function or airway hyperresponsiveness in asthmatic patients.

Adolescent↗
PubMed1993

Vacuum cleaning decreases the levels of mite allergens in house dust.

To investigate the capacity of chemical treatment of surfaces and the difference in capacity among common vacuum cleaners to reduce mite allergen content in house dust, we recruited 52 families with allergic children. Ten families used their central vacuum cleaners. Forty-two families were randomly divided into four groups with 10 or 11 families in each. These families used either new vacuum cleaners with either HEPA (High Efficiency Particulate Air) or micro-filters, or their own vacuum cleaners with either tannic acid or placebo. Dust samples were collected from carpets and upholstered furniture in the living rooms and from the mattresses of the children at Days 0, 7, 21, and 35. Der pI and Der fI allergens were determined by sandwich ELISA. After one week, tannic acid reduced the concentration of mite allergens/g of dust and the total amount/sampling area by 30% and 34%, respectively (p < 0.05), but there was no significant decrease in relation to placebo. After 5 weeks, central, HEPA- and micro-filter vacuum cleaners decreased the mite allergen concentration by 10-50% (p < 0.05) and the total amount of mite allergen from the investigated areas by 50-85% (p < 0.01). In relation to the placebo group the decrease was significant for HEPA- and micro-filter vacuums (p < 0.05). The total amount of mite allergens/sampling area was more significantly (p < 0.05) reduced than the concentration/g of dust. We conclude, that tannic acid reduces mite allergen concentrations in dust and total amount/sampling area for a short period of time.(ABSTRACT TRUNCATED AT 250 WORDS)

Allergens↗
PubMed2005

Mites in dust samples from mattress surfaces from single beds or cribs in the south Brazilian city of Londrina.

The aim of this study was to investigate the mite fauna in mattresses dust samples from cribs or beds in the south Brazilian city of Londrina, State of Parana. A total of 133 dust samples from upper and lower mattress surfaces, and bed frames were aspirated once from 38 dwellings (18 cribs and 21 beds), and one day nursery (six cribs). A total of 758 mite bodies were counted in slides: 233 (30.7%) from cribs and 525 (69.3%) from beds (p<0.001). House dust mites--mainly Dermatophagoides pteronyssinus, represented 72% and 84% of total mite count in crib and bed dust samples, respectively. The mean HDM body concentration in crib or bed slides were, respectively, 289.9+/-136.7 and 875.0+/-183.6 mites/g. Statistical analysis showed a significantly higher mite bodies count on lower mattress surface compared with upper surface in bed samples only (p=0.025). Data herein show that cribs like mattress have sufficient mite bodies to cause sensitization to humans. The use of mattress covers for cribs and beds should be encouraged in order to avoid allergens exposure.

Adult↗
PubMed2002

Isolation and characterisation of a 13.8-kDa bacteriolytic enzyme from house dust mite extracts: homology with prokaryotic proteins suggests that the enzyme could be bacterially derived.

Bacteriolytic activity was detected in extracts of whole mite and spent growth medium (SGM) from the clinically important Dermatophagoides pteronyssinus and Dermatophagoides farinae mites and was most abundant in whole mite extract. Gram-positive organisms Micrococcus lysodeikticus, Bacillus megaterium and Listeria monocytogenes were preferentially lysed and the lytic activity was enhanced by thiols, destroyed by mite proteases, inhibited by HgCl2 and high concentrations of NaCl but was resistant to heat and acid treatment. Substrate SDS-PAGE analysis indicated the presence of several lytic enzymes, two of which were isolated from D. pteronyssinus spent growth medium extract by hydroxyapatite chromatography. The N-terminal amino acid sequence of one of them was then used in PCR-based cloning studies. The complete amino acid sequence of this protein was determined and cDNA found to encode a 130-amino acid residue mature protein with a 20-amino acid leader sequence. The deduced protein demonstrated sequence similarity with the C-terminal regions of a group of bacterial proteins belonging to the P60 superfamily. These data suggest that the enzyme is derived from bacteria within the mites rather than from mites per se.

Amino Acid Sequence↗
PubMed1988

Sensitization of children in the Stockholm area to house dust mites.

Atopic sensitization of children in the Stockholm area to house dust mites (HDM) was investigated in a case-control study. Sixty children with and 60 without positive skin prick tests for HDM were matched for age and sex. HDM-sensitized children had previously more often lived in other areas known to be mite infested than the control children. Sensitization to mites was related to dampness in the homes, but no significant relationship was found to the type of residence, frequent visits to a summer house in the archipelago or parental smoking. Dust samples from mattresses of the children with the strongest positive reactions to mites in skin prick tests and the respective controls were subjected to an enzyme immunoassay, to measure the content of the major allergens of the Dermatophagoides (D.) species D. pterinyssinus, D. farinae and D. microceras. Mattress dust samples from the beds of HDM-sensitized children contained significantly higher HDM antigen concentrations than those from the beds of controls. Private houses contained significantly more HDM antigens than flats and 10 of 11 homes in which a dampness problem was recognized contained mite antigens. It is postulated that mite infestation is increasing in the area, energy-saving measures creating improved conditions for HDM survival.

Adolescent↗