Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “MITES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 865 records · Page 48Linked to original sources
PubMed1992

Mechanical transmission of Venezuelan equine encephalomyelitis virus by hematophagous mites (Acari).

Studies were undertaken to determine whether two species of hematophagous mites could transmit Venezuelan equine encephalomyelitis (VEE) virus to suckling mice. The chicken mite, Dermanyssus gallinae (De Geer), mechanically transmitted this virus to previously uninfected mice up to 16 h after taking a blood meal from a viremic animal. In contrast, Laelaps kochi Oudemans failed to transmit virus to mice in any feeding trials. Virus did not replicate in either species of mite but was detected in 20% of D. gallinae and in 12% of L. kochi specimens tested 48 h after a viremic blood meal. In mites inoculated intracoelomically with virus, recovery rates declined over time, but virus was detected up to 7 d later in 5% of D. gallinae and up to 3 d later in 10% of L. kochi. Biological transmission of VEE virus was not demonstrated in either species of mite.

Animals↗
PubMed1993

Inefficient mechanical transmission of Langat (tick-borne encephalitis virus complex) virus by blood-feeding mites (Acari) to laboratory mice.

One day after feeding on a viremic mouse, tropical rat mites, Ornithonyssus bacoti (Hirst), transmitted Langat (tick-borne encephalitis virus complex) virus to a naive suckling mouse in one of four trials. However, no transmissions to naive mice by O. bacoti were recorded either immediately after the viremic blood meal (0/4 trials) or on days 4-18 (0/20 trials). After feeding on a viremic mouse, chicken mites, Dermanyssus gallinae (De Geer), failed to transmit Langat virus to naive suckling mice in any trials (0/24). Although virus failed to replicate in either species of mite, it was detectable in 20% (2/10) of O. bacoti individuals 1 d after a viremic blood meal, but only immediately after the viremic blood meal in 20% (2/10) of D. gallinae mites. Neither mite appears to be an efficient vector of Langat virus.

Animals↗
PubMed1999

Enzymatic analyses of house dust mite extracts from Dermatophagoides pteronyssinus and Dermatophagoides farinae (Acari: Pyroglyphidae) during different phases of culture growth.

The majority of clinically important allergens of Dermatophagoides pteronyssinus (Trouessart, 1897) and Dermatophagoides farinae Hughes, 1961 present enzymatic activity. The allergenic enzymes described include cysteine proteases in group 1 allergens, trypsins in group 3, amylases in group 4, and chymotrypsins in group 6. Apart from these, other possibly allergenic enzymes also have been identified. Therefore, enzymatic profiles were studied during the 3 growth periods of the mite population--latency phase, exponential growth phase, and death phase. The activity of 19 different enzymes was analyzed by means of the Api Zym system, a method that has been used to study both mite extracts and other allergenic materials. Our study has demonstrated that the extracts contain a large variety of enzymes. It has been observed that enzymatic activity is caused exclusively by mites because the control carried out on the culture medium was negative for all the enzymes studied. Generally, the levels of diverse enzymatic activity increased with the growth of the culture, and decreased later, in both species. However, proteases are the exception; they maintain a high level of activity during the death phase of the cultured mites. The ratio between trypsin and chymotrypsin activity can be used as an excellent tool for quality control parameters during obtention of allergenic mite extracts.

Animals↗
PubMed1994

Cloning and expression of cDNA coding for a new allergen from the house dust mite, Dermatophagoides farinae: homology with human heat shock cognate proteins in the heat shock protein 70 family.

An immunoreactive clone, which shares no homology with the major allergens, Der f I and Der f II, was isolated by screening of a Dermatophagoides farinae cDNA library with rabbit antiserum raised against an extract of the house dust mite and sera from patients with mite allergy. The deduced amino acid sequence of the cDNA of the clone is significantly homologous, up to 65.5%, to the carboxyl-terminal region of the heat shock cognate protein (hsc) 71 in the heat shock protein (hsp) 70 family. A pool of the recombinant protein-specific IgE purified from mite-allergic sera recognized a 67 kDa protein on a blot of ATP-binding components partially purified from the mite body extract, while the antibody did not bind to the major allergens. We conclude that the recombinant protein, one of several important allergens, may be a protein in the heat shock protein 70 family from the house dust mite, D. farinae.

Allergens↗
PubMed2004

Acaricide resistance in northern fowl mite (Ornithonyssus sylviarum) populations on caged layer operations in Southern California.

Southern California caged layer operations were visited over 3 yr. Northern fowl mites from 26 field populations were tested for acaricide resistance using a capillary pipette and glass dish bioassay. One was a susceptible field population with no pesticide exposure for over 30 yr (reference site for resistance ratio calculation). Technical and commercial formulations of malathion, carbaryl (Sevin), permethrin, and a commercial formulation of tetrachlorvinphos/dichlorvos (Ravap) were tested. Malathion did not have high activity for mites relative to other materials, but resistance to both technical and commercial formulations was low (< 5x). Resistance to other materials was moderate to extreme. Frequency of carbaryl resistance (> 10x) was higher with the commercial (88%) than the technical material (41%); 19% of the populations had resistance > 100x to commercial carbaryl. Frequency of Ravap resistance (> 10x) was 68%; 8% of populations had resistance > 100x. Frequency of permethrin resistance (> 10x) was 72% for the technical material and 88% for the commercial formulation. Extreme permethrin resistance (> 1,000x) was observed in 56 and 50% of mite populations assayed using the technical and commercial formulations, respectively. Among sites, resistance to permethrin was uncorrelated with resistance to other chemicals, suggesting a different resistance mechanism. Resistance to carbaryl and Ravap was highly correlated [r = 0.76 at the LC50 level (concentrations estimated to be lethal to 50% of the test population) and r = 0.99 at the LC95 level], suggesting a common resistance mechanism. Producers currently depend completely on pesticides to control mite infestations. Mite resistance to registered materials emphasizes the need for integrated control measures.

Agriculture↗
PubMed1989

Atopic dermatitis and house dust mites.

The occurrence of house dust mites (Dermatophagoides spp) was investigated in the homes of 26 patients with atopic dermatitis (AD), 20 patients with psoriasis and 41 randomly selected homes in Arhus, Denmark. The AD patients with moderate to severe eczema had an increased concentration of mites (median 85 mites/0.1 g mattress dust) compared with the controls (median 8 mites/0.1 g mattress dust). The higher exposure to house dust mites corresponded to a relative risk of 4.6 and a clear dose-response relationship between exposure and disease could be demonstrated. Our results illustrate a clear association between moderate to severe atopic dermatitis and increased exposure to house dust mites in the patients' homes, and support the hypothesis that mite antigens could be an aetiological factor in atopic dermatitis.

Adolescent↗
PubMed1975

Mites and house dust allergy. IV. Antigen and allergen(s) of Dermatophagoides pteronyssinus extract.

The antigenic composition of D. pteronyssinus extract was investigated by using antisera raised in rabbits by injection of the mite extract in Freund's adjuvant. Immunodiffusion analysis revealed the presence in the mite extract of many antigenic constituents, most of which were also common to human dander and house dust extracts. Four antigenic components not shared by human dander appeared to be common to D. farinae extract. D. pteronyssinus extract was then fractionated on Sephadex G-75 and DEAE-Sephadex. Immunodiffusion analysis of the most active fraction revealed, after heat-treatment, the presence of three precipitin lines, one of which appeared not to be shared by nutrient medium or by D. farinae extract constituents. When the anti-mite rabbit serum was fixed to an immunosorbent and incubated with a house dust extract it was constantly able to induce a strong decrease or a complete loss of the allergenicity of the dust extract in man. These results suggest that mite allergen(s) are immunogenic in the rabbit and provide more direct evidence for identity of the allergens in house dust and mite.

Allergens↗
PubMed1977

Selective isolation of allergens. I. Reaction of house dust mite extracts with tridacnin and concanavalin A and examination of the allergenicity of the isolated components.

Tridacnin, a lectin from the clam Tridacna maxima was found to precipitate with crude extracts from the house dust mites Dermatophagoides farinae and Dermatophagoides pteronyssinus. Using tridacnin in direct precipitation and affinity chromatography studies, a carbohydrate-rich preparation of high molecular weight was isolated from D. farinae extracts. The isolated preparation gave one precipitin line when used with tridacnin in gel diffusion and immunoelectrophoresis experiments but two bands were seen on polyacrylamide disc gels after electrophoresis at pH 8.9. Radioallergosorbent test (RAST) studies demonstrated that the isolated material reacted strongly with sera from human subjects allergic to house dust mites and accounted for a significant proportion of the IgE binding capacity of the crude D. farinae extracts. Only one out of fifteen mite-allergic subjects gave a positive response when prick tested with the isolated preparation at a concentration of 0.2 mg/ml. A possible explanation for the discrepancy observed between RAST and skin test results is discussed. Concanavalin A also precipitated with D. farinae extracts but the material isolated with this lectin did not react with tridacnin and reacted weakly in the RAST with sera from mite-allergic subjects. We suggest that the high molecular weight component(s) which react with tridacnin may be useful for immunotherapy of house dust mite allergy.

Allergens↗
PubMed1981

House dust mite counts in different types of mattresses, sheepskins and carpets, and a comparison of brushing and vacuuming collection methods.

Mite counts were compared in dust from three types of mattresses. Foam rubber mattresses appear preferable for mite sensitive atopic subjects; the surface of kapok mattresses averaged twice, and innerspring mattresses three times, the number of mites per square metre found on foam rubber mattresses (P less than 0.01). Sheepskins used for infant bedding were also found to be heavily infested, harbouring as many mites per square metre as bedroom carpet. Mite collections are best made with vacuum sampling methods in preference to a brush and results are best expressed in mites/m2.

Animals↗
PubMed1987

Controlled trial of house dust mite avoidance in children with mild to moderate asthma.

Twenty-six asthmatic children participated in a controlled trial of house dust mite avoidance. Group A (n = 14) had 12 weeks' avoidance, provided that they had not deteriorated at the end of the first 6 weeks. Group B (n = 12) had an initial 6 weeks' observation period followed by 6 weeks' avoidance. Mite numbers were extremely variable and often low. There was a significant fall in mite numbers in the first, but not the second, 6-week period in group A. In group B there was a significant fall in mite numbers in both the first (observation) and second (active avoidance) periods. Active avoidance produced highly significant falls in total serum IgE. There were no significant changes in IgE during the observation period. This impressive immunological effect was not associated with any changes in the radio-allergo-sorbent assay (RAST) to house dust mite, or symptom scores; peak expiratory flow rates or histamine induced bronchial reactivity. More rigorous avoidance procedures in more severely affected asthmatic patients warrants further investigation.

Adolescent↗
PubMed1990

House dust mite sensitivity: a comparison of immune response with exposure to four species of Pyroglyphidae.

Twenty-five atopic children under 11 years of age were studied, using skin and RAST tests, for their specific IgE response to four species of pyroglyphid house dust mites, Dermatophagoides pteronyssinus, D. farinae, D. microceras and Euroglyphus maynei. All of the children were sensitive to D. pteronyssinus, 20 (80%) of these children were also sensitive to D. farinae and D. microceras, and 16 of the latter (64%) were also sensitive to E. maynei. Dust samples from various sites in the homes of the children revealed D. pteronyssinus in all homes studied but no D. farinae or D. microceras. E. maynei, although identified, was not present in significant numbers in any site. A control group of 20 atopic children of similar age who were not sensitive to house dust mite allergens had a similar exposure to the four mite species. These results suggest that factors in addition to mite exposure are important in the development of specific IgE responses to house dust mites.

Animals↗
PubMed1991

Exposure and sensitization to dust mite allergens among asthmatic children in São Paulo, Brazil.

A group of 20 mite allergic asthmatic children aged 6-12 years old, living in São Paulo, Brazil, was studied regarding their degree of sensitization to house dust mites and exposure to mite allergens in their homes. In 18 out of 20 houses at least one dust sample was obtained which contained greater than 10 micrograms Der p I/g of dust. The highest levels of Dermatophagoides pteronyssinus allergens, Der p I and Group II, were measured in bedding samples (geometric mean 38.4 and 36.6 micrograms/g, respectively), followed by bedroom floor, TV room and kitchen. Mite allergen levels in Brazilian houses were as high as those reported to be associated with sensitization and acute attacks of asthma in other parts of the world. In keeping with previous reports that D. farinae is rarely found in Brazil, Der f I was undetectable or found in very low levels (less than 0.5 micrograms/g). Levels of cat allergen Fel d I of greater than 8 micrograms/g of dust were obtained only in 2 houses only. Cockroach allergen Bla g I was detected in five out of 20 houses. Levels of IgE antibodies to D. pteronyssinus were greater than 200 RAST U/ml in 19 out of 20 children (geometric mean 1588 RAST U/ml). IgE antibodies to cat, cockroach, A. fumigatus, ragweed and rye grass pollens were undetectable or less than 80 RAST U/ml. IgE antibodies to the mite Blomia tropicalis were also measured, and levels greater than 200 RAST U/ml were observed in 13 out of 20 sera.(ABSTRACT TRUNCATED AT 250 WORDS)

Allergens↗
PubMed1993

Importance of house dust mite and Alternaria allergens in childhood asthma: an epidemiological study in two climatic regions of Australia.

The relation of house dust mite allergen levels to asthma and allergy was examined in two population samples of children aged 8-11 years in northern New South Wales. We studied 805 children in Lismore (a hot, humid, coastal region) and 770 in Moree/Narrabri (a hot, dry inland region). Respiratory symptoms were measured by questionnaire, bronchial hyperresponsiveness (BHR) by histamine inhalation test, and allergy by skin-prick tests. Current asthma was defined as the presence of both wheeze in last 12 months and BHR. Der p I levels were measured in dust from the bed and floors in the homes of 57 randomly selected children in the coastal region and of 74 inland children. Der p I levels were significantly higher by the coast (83.0 vs 11.2 microg/g, P < 0.001). House dust mite sensitivity was of similar prevalence in both regions (28.6 vs 26.4%, n.s.) but Alternaria sensitivity was higher inland (4.0 vs 15.2% P<0.001). Bronchial responsiveness was more severe in coastal children sensitized to house dust mites and in inland children who were sensitized to Alternaria. The adjusted odds ratios for current asthma in children sensitized to house dust mites were 21.3 (95% CI 10.5, 43.2) by the coast and 2.7 (95% CI 1.3, 5.4) inland, and in children sensitized to Alternaria were 3.4 (95% CI 1.3, 9.1) in the coastal region and 5.6 (95% CI 3.1, 10.1 inland. These studies suggest that high house dust mite allergen levels in a humid, subtropical region act to significantly increase bronchial responsiveness in sensitized children, and that Alternaria allergens have a similar but less potent action in a dry, rural region.

Allergens↗
PubMed1993

Mite allergen content in mattress dust of Dermatophagoides-allergic asthmatics/rhinitics and matched controls.

It has been suggested that the mites Dermatophagoides pteronyssinus and D. farinae are important indoor environmental factors facilitating both the sensitization of atopic subjects and asthmatic attacks of house dust-sensitive patients. Contradictory results have been reported about the current exposure to mites or their allergens among patients and control groups of atopic or non-atopic subjects. In order to determine whether there is a difference in mite exposure levels between D. pteronyssinus-sensitized asthmatics and/or rhinitis and control subjects we considered a case-control study of 70 patients with asthma and/or rhinitis and positive skin test reactions to D. pteronyssinus and twice as many control subjects who were matched as to age and sex. The first control subject for each patient was an immediate neighbour of the patient and the second was patient arbitrarily chosen among hospitalized patients. Mite allergen exposure was measured in mattress dust collected under standardized conditions, by measuring Der p I+Der fI content and by performing a semiquantitative guanine determination (Acarex-test). The content of Der p I and Der fI was very high both in the homes of patients and those of healthy individuals: 69% of the total samples contained more than 10 micrograms Der pI+Der fI/g of dust. There was no significant difference between cases and controls with respect to Der p I, Der fI, Der p I+Der fI content and Acare class distributions. The calculated odds-ratios associated with the Acarex test and the mite allergens did not differ significantly from the level 1.0.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Reduced mite allergen levels in dwellings with mechanical exhaust and supply ventilation.

Seventy similar bungalows constructed between 1968 and 1970 in the same suburban area of Stockholm were investigated regarding the content of house dust mite allergen, absolute indoor humidity, type of ventilation and basement construction. Houses with mechanical exhaust and supply ventilation had an indoor humidity above 7 g/kg less often than houses without this type of ventilation (Odds ratio 0.1, 95% confidence interval 0.0-0.2). Furthermore, only five of the 24 houses with exhaust and supply ventilation contained mattress dust mite allergen concentrations exceeding the median value (98.5 ng/g) compared with 30 of 46 hours which did not have such ventilation (odds ratio = 0.1, C.I. 0.0-0.5). Houses with both natural ventilation and crawl space basement harboured significantly less mattress mite allergen than houses having the same type of ventilation, but with a concrete slab basement. In a cold temperature climate, type of building construction and ventilation seem to be important for the occurrence of house dust mite allergens in dwellings. Our results indicate that modern energy-efficient houses should be equipped with mechanical exhaust and supply ventilation to reduce indoor air humidity during the dry winter months and the risk of mite infestation.

Air Pollution, Indoor↗
PubMed1994

Allergy to storage mites.

There is now much evidence of sensitization to storage mites in urban populations as well as in the well-documented rural populations. Sensitization is therefore not restricted only to those with occupational exposure. There appears to be a limited allergenic crossreactivity between storage mites and house dust mites, although both species also possess their own unique allergens. More research on identification and characterization of storage mite allergens and their crossreactivity is needed to understand their complexity. Such studies are necessary to obtain high quality extracts for diagnosis and possible immunotherapy. Development of immunoassays employing MoAbs will allow measurement of storage mite concentrations in workplaces and houses and the study of exposure-response relationships.

Allergens↗
PubMed1994

Comparison of the levels of the major allergens Der p I and Der p II in standardized extracts of the house dust mite, Dermatophagoides pteronyssinus.

Allergy to the house dust mite Dermatophagoides pteronyssinus is mediated by IgE to the major allergens Der p I and Der p II in the majority of mite-allergic patients. In recent years, standardized preparations of D. pteronyssinus, commercially available from several sources, have become widely used for the diagnosis and immunotherapy of mite allergy. As standardization implies uniformity of allergen composition and potency, we directly compared the absolute and relative quantities of Der p I and Der p II in six different commercial standardized extracts of D. pteronyssinus. Our findings reveal variability in levels of both Der p I and Der p II, producing ratios of Der p I/Der p II ranging from 1.1/1 to 6/1. Although the content of minor allergens in the extracts was not evaluated here, their contribution to the overall reactivity of mite-allergic patients to the commercial extracts was judged to be minimal. This was demonstrated by showing that plasma depleted of reactivity to both Der p I and Der p II had virtually no residual IgE directed against extract components. The variation in the proportion of Der p I and Der p II among different D. pteronyssinus extracts is likely to influence their biological effectiveness. Patients with reactivity against only Der p I or Der p II, who were found to comprise approximately one-third of the mite-allergic population, may not respond optimally to extracts containing relatively low levels of the allergen to which they are sensitive.

Allergens↗
PubMed1994

House dust mite allergen (Der p I) and respiratory symptoms in children: a case-control study.

The association between house dust mite allergen in house dust and childhood respiratory symptoms was investigated in a case-control study of 259 children with reported chronic respiratory symptoms and 257 control children without reported respiratory symptoms. The Der p I concentration in floor dust of the living room and bedroom and in mattress dust was determined using an enzyme immunoassay. Venous blood samples were taken from all children for serum IgE determination against house dust mite (Dermatophagoides pteronyssinus) by radioallergosorbent assay (RAST). A questionnaire was administered to the parents of the children to elicit information about the home, about changes made to the home in the past in relation to respiratory symptoms, and about a number of risk factors for childhood respiratory disease. In 83% of the dwellings of cases and 89% of those of controls, Der p I concentrations higher than 2000 ng/g were found, and in 54% of the dwellings of cases and 57% of those of controls, the concentrations exceeded 10,000 ng/g dust. In a crude analysis, cases were generally exposed to lower Der p I concentrations than controls. Restriction of the analysis to cases sensitized to dust mites, and non-sensitized controls, taking the type of floor covering into account, showed not significantly higher Der p I concentrations in bedroom floor dust of cases. However, restriction of the analysis to cases sensitized to dust mites and cases not sensitized to house dust mites--adjusting for allergen avoidance measures taken in the past--revealed a positive association between the Der p I concentrations in bedroom floor dust and mattress dust and sensitization.(ABSTRACT TRUNCATED AT 250 WORDS)

Allergens↗