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Systemic activity of nifluridide against sucking lice and the common scabies mite on cattle.

Psoroptes ovis [Hering] mites and sucking lice (Linognathus vituli Linnaeus) were eliminated from light to heavily infested calves with a single subcutaneous injection of nifluridide in five separate experiments. The compound was incorporated in a copolymer vehicle in a sesame oil suspension. In the first two experiments, mites were eliminated within 10 days following a 20 mg kg-1 injection. Eight out of 9 calves were cleared of mites within 7 days post injection of nifluridide at 4, 6 and 9 mg kg-1 in the third experiment. At the end of the 65 day trial, no live mites were isolated from any of the treated animals. In the last two experiments nifluridide eliminated sucking lice populations at all dosage levels. Complete control of the biting lice (Bovicola bovis) was not obtained. No toxic signs were observed in treated calves.

Animals↗

Infectivity of Moniezia benedeni and Moniezia expansa to oribatid mites from Ohio and Georgia.

Six species of oribatid mites belonging to four families and five genera were successfully infected by M. benedeni. They were Scheloribates laevigatus (Scheloribatidae), Exoribatula sp. cf. biundatus (Scheloribatidae), Xylobates capucinus (Haplozetidae) and Zygoribatula undulata (Oribatulidae) from Ohio, and Galumna ithacensis (Galumnidae) and Scheloribates lanceoliger (Scheloribatidae) from Georgia. Cysticercoids were also recovered from S. laevigatus infected with M. expansa. Among the six species of mites, S. laevigatus is the major intermediate host of M. expansa and M. benedeni worldwide, while the other five species have not been previously reported as transmitters of Moniezia spp. This is also the first report of any species from the genera Exoribatula and Xylobates as intermediate hosts of tapeworms. Different species of oribatid mites varied in their efficiency as intermediate hosts of M. benedeni. Moniezia benedeni had higher infection rate and infection intensity in S. laevigatus than in other species. Development in S. laevigatus was also more rapid than in the other species. Mite size was only one of the determinants of intermediate host efficiency. Storage at 4 degrees C for 1 to 5 weeks reduced the viability of M. benedeni eggs. Stored eggs had lower infection rates and infection intensity and slower development in S. laevigatus. They also had lower infection rates in X. capucinus and Exoribatula sp. cf. biundatus.

Animals↗

Spectrum of activity of doramectin against cattle mites and lice.

A series of 16 studies was conducted involving 288 cattle with naturally acquired or experimentally induced mite or louse infestations to evaluate the efficacy of doramectin. Four studies were conducted against the mite species Psoroptes bovis and two against the mite species Sarcoptes scabiei. Ten studies involved cattle with one or more of the following louse species: Damalinia bovis, Haematopinus eurysternus, Linognathus vituli and Solenopotes capillatus. In each study, a group of at least nine but not more than 25 cattle were randomly allocated to a control or a treated group. One group was treated with doramectin at 200 micrograms kg-1 and the other group received no medication. Mites or lice were quantified by species immediately before treatment and at weekly intervals for 4 weeks thereafter. Doramectin was 100% efficacious against infestations of P. bovis, Sarcoptes scabiei, H. eurysternus, L. vituli and Solenopotes capillatus. The drug reduced infestations of D. bovis by a mean of 82%.

Animals↗

Effect of a fluvalinate-resistance-associated sodium channel mutation from varroa mites on cockroach sodium channel sensitivity to fluvalinate, a pyrethroid insecticide.

Fluvalinate is a pyrethroid insecticide that is widely used in the control of the varroa mite (Varroa destructor), an ecto-parasite of the honeybee. Previously we identified four fluvalinate-resistance-associated mutations in the sodium channel gene of the varroa mite. One of the mutations caused a leucine (L) to proline (P) change at 1770 in the linker connecting domains III and IV of the sodium channel. Interestingly, at the position corresponding to the L to P mutation, all known insect (including honeybee) sodium channel proteins already naturally contain a P residue (e.g., P1577 in the cockroach sodium channel BgNa(v)). To determine whether insect sodium channels are less sensitive to fluvalinate than arachnid sodium channels, we replaced P1577 with an L in a BgNa(v) variant (BgNa(v)1-1) and examined the sensitivity of the recombinant channel to fluvalinate. The P1577L substitution did not alter the gating properties of the BgNa(v)1-1 channel expressed in Xenopus oocytes. However, the BgNa(v)1-1(P1577L) channel was five-fold more sensitive to fluvalinate compared with the BgNa(v)1-1 channel. These results not only implicate the L to P mutation in fluvalinate resistance in varroa mites, but also suggest a possible contribution of L1770 to the higher sensitivity of varroa mites to fluvalinate than their insect hosts.

Animals↗

Are atopy and specific IgE to mites and molds important for adult asthma?

BACKGROUND: Atopy is known to be important for childhood asthma, but this is to our knowledge the first study on its relation with development of asthma in adulthood. OBJECTIVES: We addressed the role of atopy, measured as total IgE and Phadiatop, and of specific IgE antibodies to mites and molds in development of adult-onset asthma. METHODS: A population-based incident case-control study was conducted in the Pirkanmaa District in Southern Finland. All new clinically diagnosed cases of asthma 21-63 years of age were recruited 1997-2000 in the study district. A random sample of the source population formed the controls. A total of 485 cases and 665 controls provided a serum sample. Diagnosis of asthma was based on demonstration of reversibility in lung function investigations. Subjects with previous asthma were excluded. Phadiatop score and IgE antibodies were analyzed with the UniCAP system. RESULTS: The adjusted odds ratio of asthma increased with total IgE and Phadiatop score in a dose-dependent pattern. IgE antibodies to house dust mite and storage mite were significantly related to an increased risk of asthma. Among molds, increased risk of asthma was seen in relation to IgE antibodies to Aspergillus fumigatus and Cladosporium herbarum. Population attributable fraction due to sensitization to common aeroallergens was 30% (95% CI, 23-41). CONCLUSION: Atopy is a strong determinant of asthma in adulthood. Specific IgE antibodies to mites and some molds are significantly related to increased risk of adult-onset asthma. A considerable fraction of adult asthma could be prevented by measures to reduce atopy.

Adult↗

Early innate and longer-term adaptive cutaneous immunoinflammatory responses during primary infestation with the sheep scab mite, Psoroptes ovis.

Clinical observation has indicated that Psoroptes ovis mites provoke cutaneous inflammation within hours of experimental infestation, but the nature of this reaction has not been described. After infestation of naive sheep with ovigerous P. ovis mites, significant influxes of eosinophils (P<0.004) and neutrophils (P<0.001) were detected within 24 h. A significant (P<0.001) increase in mast cell numbers was observed by 96 h post-infestation. In addition, marked degenerative and proliferative epidermal lesions were evident 24 and 96 h, respectively, after infestation. The influence of the later, adaptive response on the cellular infiltrate at the advancing margin of the lesion and the original site of infestation was also monitored. Mast cell numbers were greatest at 21 days while recruitment of eosinophils and neutrophils was maximal 63 days after infestation. Lesional severity was particularly pronounced from 42 to 63 days after infestation, but significant resolution had occurred by 84 days. Pathological changes at the advancing margin of the lesion were more severe than at the initial site of infestation, and this was reflected by the numbers of mites present. These data suggest that P. ovis elicits an early innate cutaneous response that is subsequently augmented by the development of an adaptive immune response, the intensity of which corresponds to the local population density of mites.

Animals↗

A new eriophyid mite-borne membrane-enveloped virus-like complex isolated from plants.

A decade ago, a new mite-transmitted disease was described on wheat (Triticum aesativum) and maize (Zea mays) that due to its geographical location was referred to as High Plains Disease (HPD). To determine the etiology, we established colonies of HPD pathogen-transmitting eriophyid wheat curl mites (Aceria tosichella) on wheat plants for maintenance of a continuous source of infected material. Analyses of nucleic acid obtained from infected plants showed the presence of HPD-specific RNAs ranging from 1.5 to 8 kilobases, but comparisons between the sequence of cDNAs and the databases did not reveal any clear identity with known viruses. We demonstrate that a diagnostic HPD-specific 32-kDa protein that accumulates in plants is encoded by a small RNA species (RNA-s). Upon infestation of upper wheat parts with viruliferous mites, the RNA-s encoded protein becomes detectable within a few days in the roots, indicative of an effective virus-like mode of transport. Membranous particles, resembling those observed in thin sections of infected plants, were isolated and shown to envelope a thread-like ribonucleoprotein complex containing the RNA-s encoded 32-kDa protein. This complex was associated with single-stranded (-)-sense RNAs, whereas free (+)-sense RNA was only detected in total RNA of infected plants. Based on the collective properties, we conclude that HPD is caused by a newly emerged mite-borne virus, for which we propose the name Maize red stripe virus (MRStV).

Animals↗

Der f 16: a novel gelsolin-related molecule identified as an allergen from the house dust mite, Dermatophagoides farinae.

Allergen from the house dust mite (Dermatophagoides sp.) is a major trigger factor of allergic disorders, and its characterization is crucial for the development of specific diagnosis or immunotherapy. Here we report the identification of a novel dust mite (Dermatophagoides farinae) antigen whose primary structure belongs to the gelsolin family, a group of actin cytoskeleton-regulatory proteins. Isolated mite cDNA, termed Der f 16, encodes 480 amino acids comprising a four-repeated gelsolin-like segmental structure, which is not seen in conventional gelsolin family members. Enzyme immunoassay indicated that recombinant Der f 16 protein, prepared using an Escherichia coli expression system, bound IgE from mite-allergic patients at 47% (8/17) frequency. This is the first evidence that the gelsolin family represents a new class of allergen recognizable by atopic patient IgE.

Allergens↗

Immunochemical characterization of recombinant and native tropomyosins as a new allergen from the house dust mite, Dermatophagoides farinae.

BACKGROUND: Two predominant mite species, Dermatophagoides farinae and Dermatophagoides pteronyssinus, are responsible for the immediate hypersensitivity reaction. Although a large number of antigens and allergens was detected in a whole mite culture extract, only the major allergens of Der I and II groups have been extensively studied. Much information on other important allergens remains to be accumulated. METHODS: A new allergen complementary DNA (cDNA) clone was isolated from a D. farinae protein cDNA library. The expression product of the cDNA and native tropomyosin from D. farinae were purified, characterized, and evaluated. RESULTS: An amino acid sequence deduced from the cDNA clone revealed significant homology with tropomyosins conserved in a wide range of animals. The amino acid sequences of two fragments obtained by degradation of the purified protein with cyanogen bromide coincided completely with the corresponding portions of the deduced amino acid sequence. The native tropomyosin reacted with specific IgE in the 31 sera tested at a high frequency (80.6%), comparable to that of Der f I (90.3%) and Der f II (74.2%). CONCLUSIONS: The cloned cDNA encodes tropomyosin. The high binding response of specific IgE antibodies to recombinant and native tropomyosins demonstrates that mite tropomyosin is an additional important allergen in house dust mite.

Allergens↗

In vitro T-lymphocyte response and house dust mite-induced bronchoconstriction.

BACKGROUND: There is considerable evidence that T cells may play an important role in asthma. The purpose of this study was to determine whether the responsiveness of T lymphocytes to mite allergen stimulation in vitro is a determinant of bronchial response to house dust mite (HDM) allergen challenge in subjects who are allergic to HDM. METHODS: Peripheral blood was taken from seven healthy nonatopic subjects and 23 subjects with positive skin test reactions to HDM. Of the subjects in the latter group, 16 had an asthmatic reaction on inhalation challenge with HDM extract (HDM-responders), whereas the remaining seven had a negative reaction (HDM allergic). The proportion of subsets of T lymphocytes and their activation and the amount of IL-2, IL-4, IL-5, and interferon-gamma released in the supernatants with and without stimulation with the HDM extract were determined. RESULTS: Without stimulation, the proportions of subsets of T lymphocytes and their activation were similar between groups. When stimulated with the HDM allergen, the proportion of CD4+CD25+ cells from HDM responders was significantly higher than those in the control group. Comparison within groups of cell cultures with and without stimulation with the mite allergen showed that the proportion of CD4+, CD4+CD25+, CD4+/CD8+, and CD3+HLADR+ cells were significantly increased in HDM responders with stimulation; there was a trend for CD4+CD25+ cells to be increased in the HDM-allergic subjects; no increase in any T-lymphocyte subsets was found in the control subjects. The release of IL-5 was significantly greater in HDM responsers than in the other two groups. The severity of the immediate asthmatic reaction was significantly associated with the degree of nonallergic bronchial hyperresponsiveness and the amount of IL-5 released but not with the level of specific IgE to the mite allergen or subsets of T lymphocytes with and without stimulation. CONCLUSION: The findings suggest that responsiveness of T lymphocytes to allergen challenge in vitro may play a role in determining the bronchial response to the allergen in vivo.

Animals↗

Specific depletion of the house dust mite allergen Der p 1 cereal flour prolamins.

BACKGROUND: Quantitation of Der 1 and Der 2 in dust samples by specific monoclonal antibodies is a method used increasingly to evaluate mite allergen exposure. The level of Der 1 has been proposed as a risk factor for sensitization. AIM: We report a drastic decrease in the Der 1/Der 2 ratio when dust samples are collected in bakeries. METHODS: Wheat flour and purified mites were extracted simultaneously; levels of Der p 1 and Der p 2 and cysteine protease activity were determined by ELISA and inhibition experiments. RESULTS: High titers of Der 2, but only trace amounts of Der p 1, were detected in dust collected from bakeries. Both the level and proteolytic activity of Der p 1 appeared greatly decreased when mites and wheat flour were coextracted. CONCLUSION: Group 1 protein was found to be masked by flour components, resulting in an underestimation of the mite content in bakery dust. This problem was not found for group 2 allergen.

Allergens↗

Production of a mouse/human chimeric IgE monoclonal antibody to the house dust mite allergen Der p 2 and its use for the absolute quantification of allergen-specific IgE.

A chimeric human IgE monoclonal antibody was developed against the house dust mite allergen Der p 2. This chimeric antibody (hIgE-Dp2A) was composed of the heavy-chain variable domains and light chains of the original murine monoclonal antibody retaining its binding characteristics, whereas the heavy-chain constant domains were exchanged with the human IgE heavy chain. The chimeric IgE expression level was IgE 600 IU/ml (1 IU = 2.4 ng/ml). The binding of the chimeric hIgE-Dp2A to mite extract was indistinguishable from that of the original mouse monoclonal antibody. Parallel dose-response curves were found when the binding of hIgE-Dp2A to mite extract and anti-IgE coupled to sepharose were compared. Binding levels were not identical; however, hIgE-Dp2A bound significantly better to the mite-extract sepharose. This result indicates that the commonly used anti-IgE on solid phase calibration systems may lead to an overestimation of the amount of allergen-specific IgE present in the serum sample. The less efficient binding of the detector anti-IgE in case of the anti-IgE sepharose is likely to be because of the occupation of epitopes of the IgE by the sepharose-bound anti-IgE. Dose-response curves of serial dilutions of patient samples were parallel with the hIgE-Dp2A dose-response curve, which indicates that hIgE-Dp2A behaves like natural IgE antibodies in binding to allergen coupled to solid phase. This antibody is well suited for use as a reference reagent in the RAST and enables the expression of the amount of allergen-specific IgE present in a patient sample in absolute amounts.

Allergens↗

Use of specific IgE in assessing the relevance of fungal and dust mite allergens to atopic dermatitis: a comparison with asthmatic and nonasthmatic control subjects.

BACKGROUND: Although allergens have been implicated as aggravating factors in atopic dermatitis (AD), there is little epidemiologic data on the significance of specific IgE. OBJECTIVE: We sought to compare sensitization to dust mite and fungi between patients with AD and asthmatic and nonasthmatic control subjects. METHODS: Total IgE and specific IgE to Dermatophagoides pteronyssinus, Alternaria alternata, Aspergillus fumigatus, Candida albicans, Malassezia furfur, and Trichophyton rubrum were measured in 73 patients with moderate to severe AD. Total IgE and IgE specific for D pteronyssinus, A alternata, and M furfur were also measured in sera from 156 asthmatic and 212 nonasthmatic control subjects. RESULTS: Positive correlations were found between total IgE and IgE antibodies specific for each of the antigens. IgE specific for M furfur was observed more frequently in adults compared with children with AD (P <.01). AD sera had higher levels of total IgE and a higher prevalence of positive sera to D pteronyssinus (95% vs 42% and 17% for subjects with AD, asthmatic subjects, and nonasthmatic subjects, respectively), M furfur (53% vs 1% and 0.5%), and A alternata (49% vs 29% and 18%). Among the sera from subjects allergic to mites, the contribution of IgE specific for D pteronyssinus to the total IgE levels was similar regardless of the clinical status. CONCLUSIONS: Our results demonstrate that moderate-to-severe AD is strongly associated with sensitization to dust mite andM furfur (odds ratios, 45.6 and 132 vs pooled control sera). These results suggest that both environmental allergens and colonizing fungi contribute to the severity of disease, which is consistent with the view that mite avoidance and antifungal treatment can be beneficial in the treatment of these patients.

Adolescent↗

Reducing relative humidity to control the house dust mite Dermatophagoides farinae.

BACKGROUND: Indoor relative humidity (RH) is the key factor that determines the survival and population development of the house dust mite Dermatophagoides farinae. Maintaining RH below 50% is one recommendation in a comprehensive plan to reduce house dust mites and mite allergen levels in homes. Even when mean daily RH is reduced below 50%, RH may rise above 50% intermittently for brief periods because of activities in the home (eg, cooking, bathing, and ventilation). OBJECTIVE: The purpose of this study was to determine how brief daily periods of moist air alternating with long spells of low ambient RH (0% or 35%) influence population survival and growth of D farinae. METHODS: Population growth was determined for D farinae at daily RH regimens of 2, 4, 6, and 8 hours at 75% or 85% RH alternating with 22, 20, 18, and 16 hours at 0% or 35% RH. RESULTS: D farinae populations declined at daily regimens of 2 hours at 75% or 85% RH alternating with 22 hours at 0% or 35% RH. Daily regimens of 4, 6, and 8 hours at 75% RH alternating with 20, 18, and 16 hours, respectively, at 35% RH provided sufficient moisture for small growths in population size. These growths after 10 weeks were reduced by 98.2%, 98.0%, and 97.3% for daily regimens of 4, 6, and 8 hours, respectively, at 75% RH (with the remainder of the day at 35% RH) compared with the growth of populations continuously exposed to 75% RH. Continuous exposure to 85% RH inhibited population growth, but alternating daily regimens of 16, 18, and 20 hours at 35% RH allowed small populations to develop, although they were reduced by 99.4%, 98.8%, and 99.1% compared with population growth at a continuous 75% RH. CONCLUSION: This study indicates that maintaining mean daily RH below 50%, even when RH rises above 50% for 2 to 8 hours daily, effectively restricts population growth of these mites and thus the production of allergen. To completely prevent population growth of D farinae, RH must be maintained below 35% for at least 22 hours per day when the daily RH is 75% or 85% for the remainder of the day.

Allergens↗

Attempting to control mite allergens with mechanical ventilation and dehumidification in British houses.

BACKGROUND: Allergen avoidance is of considerable interest in the treatment and even prevention of asthma. Attempts to control house dust mites have included environmental manipulation in homes in an attempt to reduce humidity below a level that favors mite survival. This appears to have some benefit in Scandinavia, but a previous attempt with mechanical ventilation heat pump recovery (MVHR) units in the UK failed to achieve the desired results. OBJECTIVE: We report a study using an additional central dehumidification modification of the MVHR (MVHRcd) in an attempt to reduce allergen levels in houses of asthmatic subjects. METHODS: Ten houses of asthmatic patients allergic to dust mites and 10 architectural control houses were studied. The active houses were fitted with an MVHRcd unit in November/December 1994 and activated in January 1995. The active and control houses were monitored continuously for internal temperature and humidity by using digital sensors in the asthmatic and control bedrooms. Dust samples were collected to determine allergen levels at baseline (January 1994) and 3, 6, 9, and 15 months after switching on the units. RESULTS: The winter seasonal average humidity fell from 50% relative humidity (RH) in control bedrooms to 37% RH in asthmatic bedrooms compared with 72% RH in the ambient air as measured on the intake of the MVHRcd systems. There was no corresponding change in seasonal mean temperature within the houses. Although the temperature and humidity weekly and seasonal means remained below the study target of 45% RH or 7 g/kg absolute humidity at 21 degrees C, there were transient rises in humidity detected by the sensors in the houses with MVHRcd systems. Allergen levels fell both in active and control houses during the study period, but there was no significant advantage gained from the installation of MVHRcd systems. CONCLUSION: The MVHRcd system failed to confer a benefit in terms of mite allergen reduction despite apparently adequate control of temperature and humidity.

Air Pollution, Indoor↗

'Vertition' of integumental organs in mites revisited: a case of fluctuating asymmetry.

Vertition in mites is defined as a meristic variation for a bilateral integumental organ with a separate genetic control for each body side. A prominent hypothesis expressed by Grandjean is the role of vertition in the evolutionary trend towards a reduced number of hair-like organs (mechano- and/or chemo-receptors) known to have occurred in many mite groups. Observations on leg setae in the two-spotted spider mite Tetranychus urticae do not support this hypothesis. Meristic variation for leg setae rather conforms to the notion of fluctuating asymmetry: the difference between the number of leg setae on the right and left sides of the body had a unimodal distribution with a mean of zero. Moreover, lack of heritability for left/right absences of leg setae in an inbred laboratory strain suggests that vertition could be purely environmental. It is therefore argued that meristic variation for hair-like organs in mites is caused by random developmental accidents not corrected by homeostatic mechanisms normally resulting in a perfect bilateral symmetry.

Animals↗

Clinical characteristics of mite allergen specific-lymphocytes stimulation test-positive Japanese cases with adult type atopic dermatitis.

To identify the correlation between the house dust mite-specific lymphocytes proliferation and other clinical parameters and clinical features, we conducted a lymphocytes stimulation test in 37 patients with atopic dermatitis. A total of 12 patients showed positive reactions (positive patients) and 25 showed no reaction (negative patients). Both the number and percentage of peripheral blood eosinophils were significantly lower in positive patients than in negative patients. Stimulation index measured by lymphocytes stimulation test showed no correlation with the total IgE level, nor the number and percentage of eosinophils. Stimulation index weakly correlated with mite-specific IgE-RAST scores both in positive patients and in negative patients. Only in positive patients, stimulation index weakly correlated with the severity measured by the clinician score method. Three out of four positive patients showed an increased stimulation index in accordance with increased clinician scores during their clinical course. These results could suggest that, in positive patients, a house dust mite allergy might be an active cause that exacerbates clinical symptoms at the time of their clinical course. Therefore, the stimulation index of the lymphocytes stimulation test might become one of the effective parameters that reflect the involvement of a house dust mite allergy in adult atopic patients.

Adult↗

[Allergy to snails and mites in children].

BACKGROUND: Anaphylactic reactions after consumption of snails by patients sensitized to house-dust mites have been reported several times. CASE REPORT: Two 8- and 10-year old children sensitized to house-dust mites developed Quincke's oedema after eating snails. Immunoallergologic investigations including pricks-test, labial test, IgE Rast confirmed associated allergy between snails and house dust mites. CONCLUSION: Considering the potential severity of anaphylactic reactions, it is necessary to warn children allergic to house dust mites and their parents about the high risk of associated allergy with snails.

Anaphylaxis↗