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PubMed2002

[Proliferation and location of Hantaan virus in gamasid mites and chigger mites, a molecular biological study].

OBJECTIVE: To study the proliferation and location of Hantaan virus (HV) in gamasid mites and chigger mites and the significance of gamasid mites and chigger mites as vectors of transmission of hemorrhagic fever with renal syndrome (HFRS). METHODS: Gamasid mites collected from the nests of wild rodents and chigger mites collected from the bodies of wild rodents and thick growth of grass in the field were raised. Two oligonucleotide primers were developed based on the gene fragments of cDNA of HV 76 - 118 strain to be used in RT-PCR. RNA was extracted from the suspension of the gamasid mites from the nests where rodents no HV had been found in whose lungs lived and from the unfed larvae of chigger mites, being formed groups of 5, 10, 30, or 50 individuals. RT-PCR was conducted to detect the HV-RNA in such suspension. The larvae, nymphs, and imagines of both kinds of mites were ground to make suspension at an interval of 20 days. Vero-E(6) cells were inoculated to measure the titer of 50% tissue culture infective dose (TCID(50))/ml of HV. Frozen sections of larvae, nymphs, and imagines of both kinds of mites were made. RT-PCR and in situ hybridization were conducted to detect the distribution of HV-positive particles. Monoclonal antigen technique was used to compare the antigenicity of the HV-RNA from the rodents, mites, and patients from the same epidemic areas. RESULTS: HV-RNA was detected in gamasid mites and chigger mites. Except in the larvae of chigger mites 60 days after collection, titers of HV were detected and increased gradually in mites at different stages of life cycle. HV-RNA positive particles were detected in the epithelial cells of midgut and ovary, with the signal denser and more numerous in nymphs than in larvae. The genotypes of HV from rodents, mites and patients in the same endemic areas were identical: HTN type virus. CONCLUSION: HV can be transmitted transstadially and proliferated in mites, gamasid mites and chigger mites play the role of vectors of transmission for HFRS.

Animals↗

PubMed1998

Mite control with low temperature washing-II. Elimination of living mites on clothing.

BACKGROUND: Allergens produced by mites are one of the principal causes of allergic disease. House dust mites can be found in significant numbers living in textile garments, and therefore development of optimal washing conditions for delicate textiles represents an important aim for domestic mite control. OBJECTIVES: Investigation of methods to eliminate house dust mites from clothing under low temperature washing conditions. METHODS: Domestic house dust mites Dermatophagoides farinae were cultured on garments under favourable conditions. The breeding success was monitored in terms of population and distribution using the free-mite Mobility Test. The mite containing garments were washed at low temperature with different commercial detergents in the presence or absence of a mite control additive containing 0.03% benzyl benzoate, and the numbers of mites surviving the washing process were assessed using the Heat Escape Method. RESULTS: The successful culture of mites in textile garments led to mite numbers of a total of at least 9000 to 10000 mites in 10 garments (Mobility Test). After washing in a domestic washing machine with detergents alone approximately 6000 remaining mites were detected in 10 garment halfs (Heat Escape Method). In contrast, mite control by the application of the same detergents together with an additive achieved a reduction to almost 50 mites. This is an additional reduction in mite numbers of 99.2%. CONCLUSIONS: It is possible to achieve mite control in delicate garments by washing at low temperature in the presence of a mite control additive providing a final concentration of 0.03% benzyl benzoate.

Allergens↗

PubMed1999

Mite fauna in the home and sensitivity to house-dust and storage mites.

In search of potential new indoor allergen sources, all mites in dust from homes of 55 asthmatic children living in three climatic regions in Sweden were counted and identified by light microscope. Antibodies of the IgE class against three house-dust mites and three storage mites were measured in corresponding serum samples. Mites were found in all but two homes from the northernmost area, where levels also were lower than in the other regions. The highest mite densities were most often found in bedrooms (50%) and living rooms (40%). Mite density was increased in homes with high humidity and was higher in bungalows than in flats. House-dust mites predominated in the south and storage mites in the east central area, particularly in kitchens and bathrooms. Mite-density and IgE-antibody levels against house-dust mites were significantly associated. The same association applied to storage mites. Other species numbered around 100 mites/g dust in some homes. Microscopy helps to identify potentially important mites. Analysing home dust only for house-dust mites will underestimate mite exposure. Storage mites may be as relevant to sensitivity as house-dust mites. As other species occasionally were found in high numbers, their relevance should also be assessed.

Allergens↗

PubMed2004

Sensitization to house dust mites in Reykjavik, Iceland, in the absence of domestic exposure to mites.

BACKGROUND: House dust mites are common sources of indoor allergens. In Reykjavik, Iceland, 9% of the young adult population had serum-specific IgE to Dermatophagoides pteronyssinus. Sensitization to mites is usually assumed to be due to exposure to house dust mites in the indoor environment. This investigation was carried out to measure the concentrations of house dust mite allergens and to investigate which species of mites were present in beds in Iceland. METHODS: A total of 197 randomly selected adults were visited at home using the European Community Respiratory Health Survey (ECRHS) II Indoor protocol. Dust samples were collected from mattresses for measurement of house dust mite allergen concentrations and to estimate the number and type of house dust mites. Additional samples from mattresses and floors were collected from the homes of 10 patients with positive skin prick tests (SPT) to D. pteronyssinus. House dust mite allergen concentrations were measured using ELISA and examination of mite species was carried out using microscopy. Climatic parameters were assessed using psychrometer readings in the bedrooms and outdoors. RESULTS: We found two single mite specimens, both D. pteronyssinus, in two dust samples. Mite allergen analyses indicated that two other dust samples had Der f 1 results close to the cut-off of 0.1 microg/g of dust. No samples were positive for Der p 1. In an additional collection of dust from the homes of 10 SPT-positive patients no Dermatophagoides spp. were found. CONCLUSIONS: Reykjavik citizens are exposed to extremely low amounts of house dust mite allergens in their homes. Possible alternative sources for sensitization are discussed, such as bird nests, exposure from travelling abroad, or other mites or invertebrates that cross-react with house dust mite allergens. Our findings suggest that exposures other than to house dust mites indoors are possible sources of mite allergen exposure.

Adult↗

PubMed2001

The biology of dust mites and the remediation of mite allergens in allergic disease.

In most temperate humid areas of the world, house dust mites are a major source of multiple allergens in house dust. Mite allergens sensitize and induce perennial rhinitis, asthma, or atopic dermatitis in a large portion of patients with allergic disease. There is convincing evidence that avoidance of mite allergen can effectively reduce allergic symptoms. Patients can be moved to a mite allergen-free environment, or mite and mite allergen abatement can be performed to reduce exposure in existing residences. Some knowledge of the biology of house dust mites is essential to understand the basis of the recommendations for reducing mites and mite allergens in homes and to appreciate the difficulty of eliminating house dust mites and mite allergens from homes. This article reviews key aspects of the biology of dust mites, the properties of mite allergens, recommendations for reducing mite and mite allergen concentrations in homes, and practical recommendations for treatment.

Allergens↗

PubMed1995

[Investigation of mites in the houses of atopic dermatitis (AD) patients, and clinical improvements by mite elimination].

Seasonal variations related to mites were investigated by the Methylene Blue Agar (MBA) method in the houses of 157 AD patients living in Tokyo. Many mites were counted in the dust from carpets, Japanese straw mats (Tatami) and the floor under Tatami. In most places, the number of mites was found to increase in summer. In winter, however, mite levels increased in sofas and Japanese seat cushions. On the other hand, only small numbers of mites were found in mite-proof products. Based on the above data, were recommended mite elimination by various scientific techniques was recommended for 34 severe AD patients. Mite levels and clinical symptoms were again checked after one year and two years in the same seasons. In 17 of the 34 cases, mite elimination was carried out completely. In these cases, the ratio of mite decrease to less than 30% was 82%, and the ratio of improvement of clinical symptoms (remarkable improvement + improvement) was 88%. Almost complete cure was noted in 7 cases. On the other hand, in the remaining 17 cases, mite elimination was performed incompletely in 12 cases, and was hardly done at all in 5 cases. The ratio of mite decrease to less than 30% was 47%, and the ratio of improvement of clinical symptoms was 35%. Therefore, it was concluded that investigation of mite levels following mite elimination procedures is a most recommendable treatment for severe AD patients who are hypersensitive to house dust mites.

Adolescent↗

PubMed1996

Mite control with low temperature washing. I. Elimination of living mites on carpet pieces.

BACKGROUND: Washing of delicate textiles at low temperature combined with mite control is one of the important aims for domestic mite prevention. OBJECTIVES: Estimation or assessment of mite numbers without and after the application of detergents or detergents with mite control additive. Trials at low temperature, detergents and washing as usual at household conditions (programme of a household washing machine). METHODS: The domestic mite Dermatophagoides farinae can be cultured on carpet samples under favourable conditions, and the breeding success monitored in terms of population and distribution using the free mite mobility test. The mite containing carpets were cut into pieces in order to investigate the effects of washing at low temperature with different commercial detergents with and without an additive for mite control. The heat escape method was used to assess the number of mites remaining on the carpet pieces. RESULTS: The estimation of the mite populations on different carpet pieces before and after washing showed that between 40 and 60% of the mites were able to resist washing, rinsing, spinning and drying. The allergen containing dust, however, was flushed out. In contrast, complete mite control was achieved by the application of the same detergents together with an additive. CONCLUSION: Mite control by low temperature washing is possible with a mite control additive provided that a concentration of benzyl benzoate of about 0.03% is achieved in the washing suds.

Animals↗

PubMed2003

Induction of direct and indirect plant responses by jasmonic acid, low spider mite densities, or a combination of jasmonic acid treatment and spider mite infestation.

Jasmonic acid (JA) and the octadecanoid pathway are involved in both induced direct and induced indirect plant responses. In this study, the herbivorous mite, Tetranychus urticae, and its predator, Phytoseiulus persimilis, were given a choice between Lima bean plants induced by JA or spider mites and uninduced control plants. Infestation densities resulting in the induction of predator attractants were much lower than thus far assumed, i.e., predatory mites were significantly attracted to plants that were infested for 2 days with only one or four spider mites per plant. Phytoseiulus persimilis showed a density-dependent response to volatiles from plants that were infested with different numbers of spider mites. Similarly, treating plants with increasing concentrations of JA also led to increased attraction of P. persimilis. Moreover, the duration of spider mite infestation was positively correlated with the proportion of predators that were attracted to mite-infested plants. A pretreatment of the plants with JA followed by a spider mite infestation enhanced the attraction of P. persimilis to plant volatiles compared to attraction to volatiles from plants that were only infested with spider mites and did not receive a pretreatment with JA. The herbivore, T. urticae preferred leaf tissue that previously had been infested with conspecifics to uninfested leaf tissue. In the case of choice tests with JA-induced and control leaf tissue, spider mites slightly preferred control leaf tissue. When spider mites were given a choice between leaf discs induced by JA and leaf discs damaged by spider mite feeding, they preferred the latter. The presence of herbivore induced chemicals and/or spider mite products enhanced settlement of the mites, whereas treatment with JA seemed to impede settlement.

Animals↗

PubMed1998

Seasonal variation of IgG subclass antibodies to house dust mite in sera from mite-sensitive asthmatic patients.

BACKGROUND: House dust mite is an important cause of bronchial asthma. Seasonal variation of environmental house dust mite allergen levels and the specific IgE antibody to house dust mite have been reported. OBJECTIVE: We studied the changes in IgG subclass antibodies to house dust mite associated with seasonal variation of house dust mite allergen levels in houses of mite-sensitive asthmatic patients. METHODS: In 14 mite-sensitive asthmatic patients, house dust mite allergen (Der f 1) contents in bedding were measured monthly, and IgG subclass antibodies to house dust mite, Dermatophagoides farinae (D. farinae), were determined by enzyme-linked immunosorbent assay (ELISA) every 3 months from July to December. RESULTS: The concentration of Der f 1 in dust from bedding reached maximum levels in August and September, and significantly decreased in November and December compared with August and September (P < .05). Levels of D. farinae-specific IgG4 antibodies significantly decreased in December compared with September (P < .05) with no statistically significant change between September and June (P > .05). Levels of D. farinae-specific IgG2 antibodies decreased significantly in December compared with June (P < .05). The levels of IgG1 and IgG3 antibodies to D. farinae showed no significant differences during the study period. CONCLUSION: These findings suggest that seasonal changes in natural exposure to house dust mite allergen might lead to concurrent changes in specific IgG4 antibodies to house dust mite in mite-sensitive asthmatic patients and each IgG subclass antibodies to house dust mite might have a different kinetics.

Adolescent↗

PubMed1998

Prevalence of sensitization to the storage mites Acarus siro, Tyrophagus putrescentiae, and Lepidoglyphus destructor in allergic patients with different degrees of sensitization to the house-dust mite Dermatophagoides pteronyssinus.

The prevalence of sensitization to the storage mites Acarus siro (AS), Tyrophagus putrescentiae (TP), and Lepidoglyphus destructor (LD) was studied in 250 sera of patients with different degrees of sensitization to the house-dust mite Dermatophagoides pteronyssinus (DP) by measuring IgE binding to extracts of the storage mites. Additionally, allergenic cross-reactivity between DP and the storage mite species was studied by RAST inhibition with five individual sera (and a pool of these sera) with moderate IgE levels to all three storage mites and to DP. Increased serum IgE to storage mites was found in 46% of the 200 patients sensitized to DP. Increased prevalence rates of IgE titers to storage mites were associated with higher IgE levels to DP. In 50 sera without sensitization to DP, only five sera showed increased IgE to one of the storage mites. Extracts of TP almost completely inhibited the IgE binding to AS, and vice versa. DP inhibited IgE binding to all storage mites up to 60%, whereas IgE binding to DP was only minimally inhibited by extracts of storage mites. In conclusion, cosensitization to storage mites is a frequent finding in patients sensitized to DP. Although this is largely the result of cross-reactivity between different mite species, it may nevertheless be of clinical significance in patients exposed to storage mites.

Adult↗

PubMed1980

Effects of anti-mite measures on children with mite-sensitive asthma: a controlled trial.

Mite counts and tests for mite antigen were performed on samples of dust taken from the bedding of 53 children with mite-sensitive asthma. The samples from damp houses and the beds or enuretic children had markedly more mites and mite-antigen than those from dry houses. although the predominant species was usually Dermatophagoides pteronyssinus, some of the beds in the damp houses were heavily infested with another pyroglyphid mite Euroglyphus maynei, so that this was the species found in the greatest numbers. D pteronyssinus antigen was found to be correlated broadly with the total mite count, but more antigen was present for a given number of mites in the mattresses than in the blankets. The children were randomly allocated into two groups, one of which carried out rigorous anti-mite measures. The amounts of dust and mite antigen were reduced, though not the numbers of mites. Peak flow readings were monitored in the two groups for eight weeks and a final assessment made by a paediatrician who was unaware of the allocation of each patient in the trial. No significant differences emerged in the progress of the two groups, both tending to improve. Measures designed to remove mites from bedding do not greatly benefit the majority of children with mite-sensitive asthma.

Adolescent↗

PubMed1986

Natural immunity to dust mites in adults with chronic asthma. I. Mite-specific serum IgG and IgE.

Natural immunity to dust mite (Dermatophagoides farinae) antigen was assessed in a population of 63 adults with a clinical diagnosis of chronic asthma. Immunity was determined by measuring immediate hypersensitivity to an intracutaneous injection of dust mite antigen, mite-specific serum IgG concentrations using a double antibody ELISA, and mite-specific serum IgE concentrations by RAST. Using these tests, 68% of the asthmatic patients exhibited a positive skin test; 38% had elevated concentrations of mite-specific IgE, and 63% had elevated concentrations of mite-specific IgG. In contrast, when analyzed individually, these tests were positive in only 10 to 11% of normal subjects or patients with chronic obstructive pulmonary disease. Only 10% of asthmatics had elevated serum concentrations of mite-specific antibodies of the IgG4 subclass. The asthmatic patients could be subdivided into 4 groups based on their immunologic reactivity to dust mites; 24% of the patients had elevated concentrations of mite-specific IgG in the absence of allergic reactivity to mites (skin test). A second subgroup (27%) exhibited allergic reactivity in the absence of elevated concentrations of mite-specific serum IgG. A third subgroup (41%) consisted of patients who exhibited both allergic reactivity and elevated IgG concentrations. The smallest subgroup (8%) consisted of patients with no measurable immunity to mites. In total, 94% of the asthmatic group exhibited a positive immune response to at least one of the dust-mite-specific tests, whereas only 26% of the normal subjects could be considered to be immune using the criteria of a positive reaction in at least 1 of the 3 tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2003

[Detection of hantaan virus from gamasid mite and chigger mite by molecular biological methods].

OBJECTIVE: To study the proliferation and location of hantaan virus (HV) in gamasid mites and chigger mites. METHODS: HV RNA in gamasid mites and chigger mites were detected by reverse transcription, polymerase chain reaction (RT- PCR) and in situ hybridization. RESULTS: The smallest quantity of mite from which HV RNA could be detected was 5 mites group. The titers of -and proliferated in mites HV RNA could be found in ovary cells and dug cells of gamasid mites and chigger mites by in situ hybridization. CONCLUSIONS: The results showed that HV could be trans-stadially transmitted and proliferated in mites, and HV always located in ovary and dug organs of mites. These results provide direct evidence at molecular level for the role of gamasid mites and chigger mites as vectors in transmission of HV.

Animals↗

PubMed1997

Mould-devouring mites differ in guanine excretion from dust-eating Acari, a possible error source in mite allergen exposure studies.

BACKGROUND AND OBJECTIVE: Measurement of guanine in dust proved a good assessment of mite allergen exposure. METHODS: Exposure to mite allergens may lead to atopic inflictions. In a semi-natural test system the development of Dermatophagoides pteronyssinus (Trouessart) and Glycyphagus domesticus (De Geer), and the presence of their guanine excretion, was examined in a dust-soiled and mouldy environment. Mites were counted after heat-escape, and guanine was detected by means of capillary zone electrophoresis. For each species, 50 mites randomly taken, were inoculated on soiled test-surfaces of 10 x 10 cm. Rough wooden board, gypsum board, tufted carpet, and a self-made mattress representing wall surfaces and home-textiles, respectively, were used. Eight weeks after inoculation with mites only, the surfaces were all mould ridden, and mite and guanine measurements were taken. The Spearman rank correlation test and the Mann-Whitney U-test were used in statistical analysis. The confidence limit was set at 1%. RESULTS: Among the various test-surfaces, no differences were found regarding total mite numbers and amount of guanine present (P > 0.01). For the dust-eating mite D. pteronyssinus, total mite numbers correlated with the amount of guanine present (P = 0.002) on all inoculated surfaces, indicating feeding on the protein-rich dust. For the mould devouring mite G. domesticus, however, no such correlation was found (P = 0.72). Apparently, they mainly consumed fungal carbohydrates during this experiment. CONCLUSION: The allergological relevance of storage mites has been under discussion for the last 25 years. In humid homes, these mites will feed almost exclusively on fungi and may produce allergenic or irritating substances different from those arising on protein-rich laboratory media used in allergen extract production or present in carpets, bedding and furniture.

Acari↗

PubMedDate not supplied

Factors influencing the clinical picture and the differential sensitization to house dust mites and storage mites.

Sensitization to house dust mites and storage mites has been studied in a number of papers, but several environmental factors and clinical conditions that differently affect sensitization to these mites are still controversial. The purpose of this study was to determine the influence of climatic conditions, occupation and patient age in the differential sensitization to house dust and storage mites, and also to search for possible different symptoms caused by each group of mites. Eighty patients sensitized to mites but not to other inhalant allergens were studied by case history and by skin prick test and serum IgE to Dermatophagoides pteronyssinus. Dermatophagoides farinae, Lepidoglyphus destructor and Tyrophagus putrescentiae. Home conditions, including content of the allergens Der p 1, Der f 1, Lep d 2 and Tp, were determined for all patients. Human activities, such as farming or similar occupations, and humidity are conditions for preferential sensitization to storage mites, while we found no difference between living in rural or urban areas. Mean age for the onset of sensitization was 6.7 years for house dust mites and 18.7 years for storage mites. Conjunctivitis was more frequent in patients allergic to storage mites, whereas perioral syndrome (itching of the tongue and swelling of the lips) was only seen in patients sensitized to T. putrescentiae. We concluded that climatic and damp conditions and human activity, but not urban or rural living environments, influence the differential sensitization to house dust mites and storage mites.

Adolescent↗

PubMed2001

[Experimental study on the roles of gasmid mite and chigger mite in the transmission of hemorrhagic fever with renal syndrome virus].

OBJECTIVE: To study the roles of gasmid mite and chigger mite in the transmission of hemorrhagic fever with renal syndrome virus (HFRSV). METHODS: Natural gasmid mite, the first generation gasmid mite, chigger mite larvas from rats, free chigger mite larva and nymph were collected and their cells were cultured to study the role of transmission HFRSV. RESULTS: HFRSV was detected from mite cells after cultured for 15 and 20 days. The number of HFRSV and fluorescence intensity detected from the fhird and fourth generation gasmid mite and chigger mite nymph was much more than those from the first, second generation and chigger mite larva. CONCLUSION: Gasmid mite and chigger mite had an important role to play on HFRSV transmission in keeping the natural cycles.

Animals↗

PubMed1988

Effectiveness of vacuum cleaning and wet cleaning in reducing house-dust mites, fungi and mite allergen in a cotton carpet: a case study.

In order to evaluate the effect of continuous, thorough vacuuming on house dust organisms and mite allergen, a cotton carpet was vacuumed every other day, six times in total. Seven weeks later, the carpet was cleaned by means of spray extraction. Samples were taken before and after this wet cleaning. In total 1150 g of dust was collected, containing approximately 174,000 arthropods (dead and alive) and 9000 X 10(6) fungal spores. In the course of the experiment, the amount of dust collected at each vacuuming decreased. The number of extracted house dust mites did not decrease significantly, but that of the predator mite Cheyletus did. The number of extracted fungal spores showed a significant decrease (from 142 to 16 X 10(6) spores/m2 per minute vacuuming), as did the extracted mite allergen per m2. After 7 weeks the number of mite eggs and complete house dust mites had increased enormously. After cleaning by spray extraction another increase in the number of complete mites and mite eggs was found, while the amount of mite allergen was diminished. The population growth of the house dust mite between the 6th and the 7th vacuuming is probably due to the decrease of their most important predator, Cheyletus. After the wet cleaning a number of extra eggs hatched, probably due to the high humidity in the carpet. The procedures used in this study to combat house dust mites may have an adverse effect in the long run.

Allergens↗

PubMed2006

Evaluation of predatory mites and Acramite for control of twospotted spider mites in strawberries in north central Florida.

Greenhouse and field experiments were conducted from 2003 to 2005 to determine the effectiveness of two predatory mite species, Phytoseiulus persimilis Athias-Henriot and Neoseiulus californicus (McGregor), and a reduced-risk miticide, Acramite 50 WP (bifenazate), for control of twospotted spider mite, Tetranychus urticae Koch, in strawberries (Fragaria x ananassa Duchesne). In greenhouse tests, three treatments consisting of releases of P. persimilis, N. californicus, and an untreated control were evaluated. Both species of predatory mites significantly reduced twospotted spider mite numbers below those found in the control during the first 3 wk of evaluation. However, during week 4, twospotted spider mite numbers on the plants treated with P. persimilis increased and did not differ significantly from the control. Field studies used releases of P. persimilis and N. californicus, applications of Acramite, and untreated control plots. Both N. californicus and P. persimilis significantly reduced populations of twospotted spider mite below numbers recorded in the control plots. During the 2003-2004 field season P. persimilis took longer than N. californicus to bring the twospotted spider mite population under control (< 10 mites per leaflet). Acramite was effective in reducing twospotted spider mite populations below 10 mites per leaflet during the 2003-2004 field season but not during the 2004-2005 field season, possibly because of a late application. These findings indicate that N. californicus releases and properly timed Acramite applications are promising options for twospotted spider mite control in strawberries for growers in north Florida and other areas of the southeast.

Animals↗