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PubMed1996

Occupational allergy due to spider mites: Tetranychus urticae (Koch) and Panonychus citri (Koch).

BACKGROUND: Allergy to both house dust and storage mites is well established, but information about other species of mites is scant. OBJECTIVE: One hundred and fifty patients directly exposed to an occupational environment were studied to assess whether spider mites (Tetranychidae) caused their allergic symptoms. We also studied a group of 50 patients from an urban environment, who were not occupationally exposed to spider mites, with a strong sensitization to Dermatophagoides pteronyssinus (RAST class 4). METHODS: Case history (including questions about work-related symptoms), skin tests, RAST and conjunctival provocation tests were performed in both groups using Tetranychus urticae and Panonychus citri extracts as allergens. Cross-reactivity between spider mites and D. Pteronyssinus was determined by RAST inhibition. RESULTS: Fifty-four of 150 rural workers were positive to Tetranychidae and in all cases there was an associated sensitization to D. pteronyssinus. All individuals belonging to the urban group were positive to spider mites. RAST inhibition demonstrated a significant cross-reactivity between Tetranychidae and D. pteronyssinus. Five of fifty-four rural workers sensitized to spider mites developed symptoms only when they handled plants or fruits infested with spider mites and they became asymptomatic when exposure ceased. CONCLUSION: In the rural population studied, 36% of workers were found to be sensitized to spider mites and 10% had symptoms associated with occupational exposure. Since specific IgE antibodies to spider mites could not be detected in the absence of the specific IgE antibodies to D. pteronyssinus, and as all the affected workers were RAST positive to D. pteronyssinus, prior sensitization to house dust mites may be a risk factor for occupational allergy to spider mites.

Adult↗
PubMed2003

Disodium octaborate tetrahydrate (DOT) application and vacuum cleaning, a combined strategy to control house dust mites.

BACKGROUND: The effectiveness of acaricides in homes is controversial. OBJECTIVE: To determine whether disodium octaborate tetrahydrate (DOT) combined with vacuuming lowers dust mite numbers and their allergens in carpets and sofas. METHODS: A 6-month study was carried out with 93 homes, which were randomized into three groups: (i). active, received DOT; (ii). placebo, received water; and (iii). control, received no application. Active and placebo homes were vacuumed weekly. Dust was collected from carpets and sofas at the start of the study and every 2 months thereafter and quantified for live, total mites, and mite allergen levels. RESULTS: At 2 months, live mite numbers in active carpets were 3 +/- 1, in placebo carpets 129 +/- 48, and in control carpets 177 +/- 39 mites/g. The corresponding numbers in sofas were 3 +/- 2, 81 +/- 31, and 134 +/- 45 mites/g, respectively (P < 0.001 active vs placebo and vs. control). Live mites in carpets and sofas remained lower in the active group at 6 months (P < 0.001). Total mites in active carpets decreased from 555 +/- 69 at baseline to 223 +/- 32 mites/g at 6 months (P < 0.001) and mite allergen levels from 1.36 +/- 0.13 to 0.85 +/- 0.16 microg/g (P < 0.001). Total mites in active sofas remained unchanged, but mite allergen levels decreased from 1.48 +/- 0.25 at baseline to 0.7 +/- 0.15 microg/g at month 6 (P < 0.05). CONCLUSION: DOT kills mites in carpets and sofas, and, combined with vacuuming, effectively reduces total mites in carpets and mite allergen levels in carpets and sofas.

Animals↗
PubMed2004

Beat sampling accuracy in estimating spruce spider mite (Acari: Tetranychidae) populations and injury on juniper.

The use of a standardized beat sampling method for estimating spruce spider mite, Oligonychus ununguis (Jacobi) (Acari: Tetranychidae), densities on a widely used evergreen ornamental plant species, Juniperus chinensis variety 'Sargentii' A. Henry (Cupressaceae), was examined. There was a significant positive relationship between total spruce spider mite densities and spider mite densities from beat sampling on juniper. The slope and intercept of the relationship may be used by pest managers to predict total spider mite densities on plants from beat sample counts. Beat sampling dramatically underestimates the total number of spider mites on a foliage sample. The relationships between spruce spider mite feeding injury and spider mite density estimates from beat sampling juniper foliage and total spider mite counts on foliage were also examined. There was a significant positive relationship between spruce spider mite density as estimated from beat sampling and injury to the plants. There was a similar positive relationship between the total number of spruce spider mites and injury to the plants, suggesting that a pest manager could use beat sampling counts to estimate plant injury and related thresholds. These findings have important implications to decision-making for spruce spider mite control, especially as it relates to threshold levels and determining rates of predator releases. Further assessment of the effectiveness of beat and other sampling methods across multiple spider mite- host plant associations needs to be examined to enable pest managers to select sampling plans that are feasible and reliable.

Animals↗
PubMed2006

Ability of a proteinase inhibitor mixture to kill poultry red mite, Dermanyssus gallinae in an in vitro feeding system.

The development of a reliable in vitro feeding system has enabled the rapid testing of presumptive anti-mite factors, a mixture of protease inhibitors (PI), by incorporating these into the blood feed. Mites were collected from a caged-hen facility and underwent a regime of starvation under varying conditions of temperature and darkness to determine the optimum conditions that encouraged mites to feed in the in vitro system. The efficacy of two anti-coagulants, heparin (HS) and acid citrate glucose (ACD), on mite feeding rates and mortality was evaluated. The ability of a mixture of PI to kill mites was also evaluated. The rate of feeding was greater in mites that were starved and cooled for between 7 and 30 days compared with mites that were not starved or cooled. The percentage of mites that fed when presented with HS treated blood (70%) was greater when compared with ACD treated blood (48%). The mortality of mites fed blood treated with HS + PI increased to 45% compared with a mortality level of 5% in mites fed on blood treated with HS alone. A reliable in vitro method for feeding D. gallinae which has the potential to be used to rapidly screen blood-borne products for their efficacy in reducing mite numbers has been developed.

Animals↗
PubMed2003

Acaroid mite, intestinal and urinary acariasis.

AIM: To investigate epidemiology and pathogenic mite species of intestinal and urinary acariasis in individuals with different occupations. METHODS: A total of 1994 individuals were tested in this study. History collection, skin prick test and pathogen identification were conducted. The mites were isolated from stool and urine samples by saturated saline flotation methods and sieving following centrifugation, respectively. RESULTS: Among the 1994 individuals examined, responses to the skin prick test of "+++", "++", "+","+/-" and "-" were observed at frequencies of 3.96 % (79), 3.21 % (64), 2.31 % (46), 1.25 % (25) and 89.27 % (1780), respectively. A total number of 161 (8.07 %) individuals were shown to carry mites, with 92 (4.61 %) positive only for stool samples, 37 (1.86 %) positive only for urine samples and 32 (1.60 %) for both. The positive rate of mites in stool samples was 6.22 % (124/1994), being 6.84 % (78/1140) for males and 5.39 % (46/854) for females. No gender difference was observed in this study (chi(2)=1.77, P>0.05). The mites from stool samples included Acarus siro, TyroPhagus putrescentiae, Dermatophagoides farinae, D. pteronyssinus, Glycyphagus domesticus, G. ornatus, Carpoglyphus lactis and Tarsonemus granaries. The positive rate of mites in urine samples was 3.46 % (69/1994). The positive rates for male and female subjects were found to be 3.95 % (45/1140) and 2.81 % (24/854) respectively, with no gender difference observed (chi(2)=1.89, P>0.05). Mites species in urine samples included Acarus siro, Tyrophagus putrescentiae, T. longior, Aleuroglyphus ovatus, Caloglyphus berlesei, C. mycophagus, Suidasia nesbitti, Lardoglyphus konoi, Glycyphagus domesticus, Carpoglyphus lactis, Lepidoglyphus destructor, Dermatophagoides farinae, D. pteronyssinus, Euroglyphus magnei, Caloglyphus hughesi, Tarsonemus granarus and T. hominis. The species of mites in stool and urine samples were consistent with those separated from working environment. A significant difference was found among the frequencies of mite infection in individuals with different occupations (chi(2)=82.55, P<0.001), with its frequencies in those working in medicinal herb storehouses, those in rice storehouse or mills, miners, railway workers, pupils and teachers being 15.89 % (68/428), 12.96 % (53/409), 3.28 % (18/549), 2.54 % (6/236), 5.10 % (13/255) and 2.56 % (3/117), respectively. CONCLUSION: The prevalence of human intestinal and urinary acariasis was not associated with gender, and these diseases are more frequently found in individuals working in medicinal herb, rice storehouses or mills and other sites with high density of mites. More attention should be paid to the mite prevention and labor protection for these high-risk groups.

Acaridae↗
PubMed2004

Occupational exposure to allergenic mites in a Polish zoo.

The study was carried out from April 2000-March 2001. During this period 49 samples of dust, litter, debris and residues from cages and run-offs of mammals, birds and reptiles in the Silesian Zoo, were examined for the presence of mites, especially the allergenic taxa. Mites were extracted using the Berlese method and preserved in 70 % ethanol. For identification, the mites were mounted in Hoyer's medium on microscope slides. Mites were found in 44 of 49 samples analyzed (89.8 %). A total of 5,097 mites were collected, from which 60.3 % were found in samples collected in spring, whereas only 13 % in summer and 24.1 % in autumn. The remaining 2.6 % of the total mite population was found in winter. Majority of mites (82.7 %) were collected from aviaries of macaws and cockatiels (Ara ararauna and Nymphicus hollandicus). A total of 10 species of astigmatid mites were identified that belong to 4 families--Acaridae, Glycyphagidae, Anoetidae and Pyroglyphidae. Generally, the allergenic mites of the order Astigmata constituted 49.5 % of the total count. Among them Acarus farris was predominant (34 % of the total count), followed by Tyrophagus putrescentiae (4.7 %), Caloglyphus sp. (4.35 %) and Acarus immobilis (4.31 %). Dermatophagoides farinae, the house-dust-mite species, was for the first time found in this environment. D. farinae (0.05 % of the total population) was associated with parrots, canids and artiodactyls. Summarizing, it should be stressed, that cages and run-offs of different mammals, aviaries of parrots and terrariums of snakes are important sources of some allergenic mites, especially A. farris and T. putrescentiae, that might cause allergies in workers.

Air Microbiology↗
PubMed1989

Mites in pulmonary cytology specimens.

Mites were observed in 55 pulmonary specimens examined routinely over a 4.5-yr period. The 55 specimens included 33 spontaneous and 12 aerosol-induced sputum samples, nine bronchial washings, and one fine-needle aspirate. Two specimens contained only fragments of mites; however, in most cases the mites were relatively intact. Many were identified as Tyrophagus sp, but a few were definitely not Tyrophagus sp. Although only a single mite was noted in most instances, eight specimens contained more than one, with the maximum being six. No patient was found to have a mite in more than one specimen. Mite eggs were found in five of the specimens containing mites. One specimen contained adults and a larval form. Mites appeared to be surrounded by acute inflammatory cells in 13 cases. Specimens were processed by the Saccomanno blending technique with smears prepared by pipetting a portion directly onto a slide or by utilizing a cytocentrifuge. No mites were found in nonpulmonary specimens. Both a seasonal variation and an interobserver variability were found. Mites often resemble specimen contaminants, such as food, and may be overlooked on routine screening. Mites are known to represent or produce a respiratory allergen, but the significance of their presence in pulmonary cytology specimens has not been determined.

Adult↗
PubMed2004

Response of soil mites to organic cultivation in an ultisol in southeast Brazil.

Soil-dwelling mites of four plots under organic management were investigated in April and December 1998 and in December 1999. Their populations were compared with mite populations in a pasture and forest in the vicinity. It was observed that there was always an initial reduction in the populations of soil mites and in the activity of the epigeic forms whenever a plot was opened up and disturbed mechanically in preparation for cultivation, irrespective of previous organic inputs. With time, the densities and activities of mites recovered under organic management. The uropodine and oribatid mites in particular benefited more from organic management than gamasine and actinedid mites. Uropodine mites increased tremendously under banana where there was fresh cow dung manure. Oribatid mite species Nothrus seropedicalensis and Archegozetes magnus were dominant in organic plots where the soil was moist and temperatures were lower than the ambient. Protoribates rioensis was dominant in organic plots where the soil was drier and temperatures were higher than the ambient. Galumna was the most active oribatid taxon on the floor of all plots, with the highest activity recorded under maracuja and in pasture plots. The results suggest that while densities and activities of soil mites increased in the organic plots, the community structure and recruitment period of oribatid mites were altered. Oribatid mite diversity was higher in the organic plots than in the pasture but lower than in the forest, where Belba sp. and many Eremobelboid brachypiline genera were present, but absent in the organic plots and pasture.

Agriculture↗
PubMed1983

Diagnosis of house dust mite allergy in asthmatic children: what constitutes a positive history?

Standardized questions were put to the parents of 530 children, referred consecutively for evaluation of asthma, to determine which features in the history were associated with house-dust mite allergy. Bronchial challenge tests performed on 19 of the children confirmed that there is a highly significant association between a positive skin prick test and a positive bronchial challenge test to Dermatophagoides farinae mite antigen. One hundred and eighteen (23%) of the children had positive prick tests to the mite. There is a highly significant association between a positive prick test to mite and a history that the subject's respiratory symptoms become worse when there is exposure to domestic activity that stirs up house dust (vacuuming, dusting, sweeping, making the bed, or shaking out blankets) or that the symptoms improve when out of doors. Seasonal variation and other features in the history are of little value in distinguishing mite-sensitive from mite-insensitive asthmatics. Although the 4% whose only positive prick test reaction was to mite had significant worsening of asthma during the colder months compared with the remainder, most mite-positive subjects had multiple allergies and had no characteristic seasonal pattern. The presence of a positive prick test to mite was not associated with aggravation of asthma either at night in bed or in the morning on awakening. A history similar to that of mite-sensitive subjects was elicited in those with a positive prick test to house dust. A positive history of house dust or house-dust mite allergy in asthmatics is one in which respiratory symptoms become worse during domestic activity that stirs up house dust or improve when outdoors.

Adolescent↗
PubMed1986

Cross-reacting and species-specific determinants on a major allergen from Dermatophagoides pteronyssinus and D. farinae: development of a radioimmunoassay for antigen P1 equivalent in house dust and dust mite extracts.

Two species of mites of the genus Dermatophagoides are common in house dust and make a major contribution to the allergen content of house dust. As judged by skin tests and the radioallergosorbent test, these mites, D. pteronyssinus and D. farinae, demonstrate extensive cross-reactivity. When the major allergen from D. pteronyssinus, antigen P1, was compared with the equivalent allergen from D. farinae, these two proteins were found to have both species-specific and common antigenic determinants. With specifically purified antibodies directed against the common determinants, we developed a radioimmunoassay for these antigen P1 equivalent proteins in mite extracts as well as house dust extracts. The quantity of allergen in dust from 63 houses (255 samples) was measured, and values ranged from less than 100 to greater than 100,000 ng/gm of fine dust. The correlation between antigen P1 equivalent (ng/gm) and the number of mites per gram of dust (identified by microscopy) was very good (r = 0.74; p less than 0.001). Furthermore, this correlation was not affected by the species of mite in the dust sample. Of 9243 mites identified, 95% were of the genus Dermatophagoides, and of these, 16.4% and 18% could be positively identified as D. farinae and D. pteronyssinus, respectively. When the assay for antigen P1 equivalent was applied to isolated components of mite cultures of both species, significant allergen was found in the mite bodies, cuticles, and their excreta (fecal particles). For the house-dust samples, less than 10% of the allergen measured could be explained by the allergen content of mite bodies. Our results demonstrate that a radioimmunoassay for antigen P1 equivalent can provide an accurate and simple means of assessing the quantity of mite-derived allergen in dust-mite extracts, house-dust extracts, or house dust.

Allergens↗
PubMed1995

House dust mite (Dermatophagoides farinae and Dermatophagoides pteronyssinus) prevalence in the rooms and hallways of a tertiary care hospital.

BACKGROUND: House dust mites, Dermatophagoides farinae and Dermatophagoides pteronyssinus, are important components in the development of asthma. OBJECTIVE: We measured the prevalence of house dust mites in a tertiary care hospital located in a temperate geographic region where dust mites were prevalent in homes. METHODS: The density of Dermatophagoides spp. was measured in hospital hallways, carpeted patients' rooms, and noncarpeted patients' rooms by vacuuming the floor in the summer and winter seasons. Bedrooms in the homes of employees were sampled as a summer control group. A total of 141 dust samples was obtained. RESULTS: No D. farinae or D. pteronyssinus was found in 60 hospital dust samples that were obtained during the winter season. Although mites were found in some locations in the hospital during the summer dust collection, mite density in these locations and the average mite density for all samples were insignificant. During the summer dust samples from the bedroom carpets of all employees' homes sampled were positive for mites, with many homes having moderate or high populations (range, 22 to 8340 mites per gram of dust). CONCLUSIONS: The dust mite prevalence in a hospital could be kept very low even though mite levels in employees' homes were moderate to high. The factors responsible for the low mite density in the hospital were maintenance of low relative humidity, use of low-pile carpets, and good housekeeping and laundering practices.

Animals↗
PubMed1996

Induction of atopic dermatitis by inhalation of house dust mite.

BACKGROUND: The pathogenetic role of house dust mite in atopic dermatitis remains controversial. Recent studies have shown that intensive epicutaneous contact of house dust mite allergen with premanipulated skin may induce dermatitis. It is, however, uncertain whether such conditions are met during natural contact with house dust mite. In the past, allergen inhalation has been suggested to induce exacerbation of atopic dermatitis. The aim of this study was to investigate whether dermatitis could be induced in patients with atopic dermatitis by inhalation of house dust mite. METHODS: Twenty patients with atopic dermatitis underwent bronchial provocations with house dust mite. Challenge tests were performed with four concentrations of a standardized house dust mite extract in a double-blind, randomized, placebo-controlled fashion. Spirometry was performed, and FEV1 was measured before and after each challenge dose. Changes in severity or localization of itching or erythema were recorded. RESULTS: In nine of 20 patients with atopic dermatitis bronchial challenge with house dust mite induced unequivocal skin symptoms after 1.5 to 17 hours. Pruritic erythematous lesions on noninvolved sites together with exacerbations of existing lesions were seen in three patients. Three patients had an exacerbation only, and three other patients had new lesions only. In eight of nine patients with house dust mite inhalation-induced dermatitis, skin symptoms were preceded by an early bronchial reaction. All patients with house dust mite-induced dermatitis had a history of asthma, and as a group they had a higher mean blood total IgE level compared with the "negative skin responders." One patient had pruritic erythema on the placebo challenge day, without a preceding bronchoconstrictive reaction. The number of patients who had a skin response on the house dust mite challenge day was significantly higher than the number of patients who had a skin response on the placebo day (p = 0.011 [Prescott's test]). CONCLUSIONS: The respiratory route may be relevant in the induction and exacerbation of dermatitis in a subset of patients with atopic dermatitis who have early bronchial reactions after house dust mite inhalation, a history of asthma, and an elevated blood total IgE level. Furthermore, these findings suggest a possible causal relationship between bronchial reactions and skin reactions.

Administration, Inhalation↗
PubMed1997

Mite-contaminated foods as a cause of anaphylaxis.

BACKGROUND: Although insect and arthropod contamination of certain foods has been recognized for many years, allergic manifestations caused by ingestion of mite allergens have only rarely been reported. OBJECTIVE: The purpose of this study is to present clinical observations in patients who experienced acute anaphylaxis after eating mite-contaminated foods. METHODS: Thirty atopic subjects who were first seen with systemic anaphylaxis precipitated by the ingestion of wheat-containing foods underwent skin prick tests with inhalant and food extracts, as well as with uncontaminated and mite-contaminated wheat flour. Flour samples were examined microscopically for identification and counting of mites. Der p 1 and Der f 1 levels were quantitated by using immunochemical methods. RESULTS: The most common symptoms were breathlessness, angioedema, wheezing, and rhinorrhea, which started between 10 and 240 minutes after eating. Abundant mites were present in the flour obtained from 28 patients; Suidasia spp. mites were found in grated bread from the other two patients. Positive prick test responses to Dermatophagoides farinae-and mite-contaminated flour and negative skin test responses to wheat extract, other food extracts, and uncontaminated wheat flour were found in all patients. Skin test responses were positive in volunteers with mite allergy even after heating the mite-contaminated flour at 100 degrees C. Screening of 35 unselected flour samples demonstrated the presence of mites in 13 of them (37.1%). CONCLUSIONS: Systemic anaphylaxis can occur after the ingestion of heated or unheated mite-contaminated foods. This problem may be more prevalent in tropical and subtropical countries than previously recognized.

Adolescent↗
PubMed2001

House dust mite, cat, and cockroach allergen concentrations in daycare centers in Tampa, Florida.

BACKGROUND: Allergen exposure in early childhood is a risk factor for sensitization and the development of asthma. Studies performed in Europe, New Zealand, and Singapore indicated the presence of indoor allergens in childcare centers and schools. However, the importance of indoor allergens in daycare centers in humid and warm regions of the world is not known. OBJECTIVE: To measure total mite counts, Der p 1, Der f 1, Fel d 1, and Per a 1 allergens in dust samples and mite allergen airborne concentrations in daycare centers in Tampa, Florida, United States. METHODS: Twenty daycare centers were surveyed for mite, cat, and cockroach allergens in Tampa, FL. One dust and two air samples (one during the day and one during the night) were collected in each center. Dust samples were extracted and analyzed for mite (Der p 1 and Der f 1), cat (Fel d 1), and cockroach (Per a 1) allergens. Mite airborne allergen concentrations were analyzed by RAST inhibition and expressed in standardized mite allergen units per m3 of air (AU/m3). RESULTS: Mites were identified in 15 samples, and concentrations ranged from 10 to 1,200 mites/g (298 +/- 355.2). The most prevalent mite species was Dermatophagoides pteronyssinus ( Der p 1). Der p 1 and/or Der f 1 were detected in 10 daycare centers. Der p 1 was detected in eight centers and ranged from I to 21.8 microg/g of dust (5.4 +/- 6.9); Der f 1 was detected in 3 centers and ranged from 0.2 to 2.1 microg/g of dust (1.3 +/- 0.9). Per a 1 and Fel d 1 were detected in all centers in small quantities; Per a 1 ranged from 8 to 1,806 ng/g (263.1 +/- 449.7) and Fel d 1 from 0.2 to 120 U/g of dust (16.6 +/- 31.7), respectively. Airborne mite allergen was detected in 18 centers and ranged from 0.01 to 2.7 AU/m3 during the day (0.2 +/- 0.6) and from 0.01 to 0.12 AU/m3 during the night (0.06 +/- 0.03), P = 0.001. CONCLUSIONS: Mite, cat, and cockroach allergens are present in daycare centers in Tampa, FL. Mite allergen concentrations exceeded levels that have been associated with sensitization and symptoms in allergic subjects in 40% of these centers.

Allergens↗
PubMed2002

Relationship among house-dust mites, Der 1, Fel d 1, and Can f 1 on clothing and automobile seats with respect to densities in houses.

BACKGROUND: Locations where there are no dust mites or pets present may contain allergens that pose a risk factor for sensitizing and inducing rhinitis and asthma. OBJECTIVE: The purpose of this study was to investigate the relationship among the prevalence of mites and mite, dog, and cat allergens in homes, on clothing, and on automobile seats. METHODS: Over a 2-year period (July 1998 to July 2000), dust mite and mite, dog, and cat allergen densities were determined in homes, associated automobiles, and on the clothing of the drivers. During this period 87 homes were sampled one to five times each. RESULTS: Low levels of live and dead mites were present in most dust samples obtained from automobile seats and in 16% from clothing. Seventy-two and 50% of the home samples had >2 microg and >10 microg Der l/g of dust, respectively, whereas 23% of automobiles seat samples had >2 microg Der l/g of dust with a mean of 1.3 microg/g. Mite and Der 1 densities were not different for homes with or without pets. However, homes with pets had significantly more Fel d 1 or Can f 1 allergen than homes without pets. Homes without cats and dogs had an average of 93 and 29 microg/g of Fel d 1 and Can f 1, respectively, which was well above threshold levels for sensitization and induction of allergic reactions. Although most clothing had detectable levels of pet allergen, the levels of these allergens were low. CONCLUSIONS: Der 1 densities in some automobiles were sufficiently high (>2 microg/g of dust) to be risk factors for sensitization and allergic reactions. However, most automobile seats had levels of dog and cat allergen that were well above the threshold levels considered to be risk factors for both sensitization and symptoms, regardless of the presence of a pet in the home. The presence of live and dead mites and mite, cat, and dog allergens in automobiles and on clothing suggests that both are vehicles in the dispersal of mites and mite and pet allergen.

Allergens↗
PubMed2000

Colonization of vineyards by phytoseiid mites: their dispersal patterns in the plot and their fate.

The effect of wind and woody margins on the dispersal and population dynamics of phytoseiid mites was studied in a vine plot for a period of two years. Mites were sampled in the plot and in the surrounding vegetation (crops and natural vegetation) in order to determine phytoseiid mite abundance. The surrounding vegetation was considered to be a reservoir of phytoseiids from where the vine plot could be invaded. Directional and non-directional soil and aerial traps were placed in the plot to determine predatory mite exchange between the two areas. Colonization of the plot occurred in two stages: first, mite migration into the plot, followed by their establishment. The two-year study partially clarified the first of these two stages. Kampimodromus aberrans was the main species caught in the aerial traps. Phytoseiid mite dispersal within the vine plot seemed to be affected by both wind (direction, intensity and regularity) and phytoseiid mite density in the woody margin. However, the woody margin had a large effect only over a short distance. Some observations pointed towards an effect of other reservoir areas but it was not possible to characterize these. The population density of the phytoseiid mites in the plot increased from 1996 to 1998, but these increases are much smaller than one would expect on the basis of the number of mites migrating by air in the plot. Moreover, blocks where most mites were trapped were not the blocks where densities of phytoseiid mites on vine leaves were the largest. It therefore seems likely that not all migrants were able to develop. Their settlement pattern was not determined and this could constitute a potential research focus for the future.

Agriculture↗
PubMed2003

The effect of sub-floor heating on house-dust-mite populations on floors and in furniture.

It is well known that dehydrating conditions for house dust mites can be created by simply raising the temperature, causing loss of body water and eventually death. Thus, it can be expected that conditions for dust mites are less favourable on floors supplied with sub-floor heating. This was examined in a study of 16 houses with sub-floor heating and 21 without. The pattern of changes in air humidity and temperature on the floors was investigated and compared to known data of the tolerance of dust mites. Also the resident mite populations were compared. Floors with sub-floor heating had, on average, fewer mites, but the difference with unheated floors was small. It was remarkable that mite numbers were also lower in upholstered furniture. Another important observation was that some houses with sub-floor heating had high mite numbers, indicating that this type of heating is compatible with a thriving mite population. Temperature and humidity conditions of heated floors may allow mites not only to survive, but also to remain active in winter. A moderate increase in temperature, a moderate decrease in (absolute) air humidity, or a combination of both, will suffice to keep the humidity all winter below the Critical Equilibrium Humidity, the level of air humidity that is critical for mite growth and reproduction, hence for allergen production. However, it is argued that measures to suppress allergen production by house dust mites are likely to be far more effective if taken in summer rather than in winter.

Air Pollution, Indoor↗
PubMed1978

Effect of reagins and allergen extracts on radioallergosorbent assays for mite allergen.

The reproducibility of the radioallergosorbent (RAST) inhibition and direct binding assys with mite allergen were investigated in the presence of heterogeneous extracts and non-mite-sensitive atopic sera. Both contain components similar to potential contaminants which would occur in the assay of mite allergen and dust allergen and dust allergen extracts. The standardized inhibition and direct binding assays employed had a day to day (n = 4) coefficient of variation [(s.d. x 100)/mean] of 15% and 24% respectively. The inhibition assay for mite allergen was reproducible in the presence of protein concentrations of added plant, fungal, arthropod and animal extracts in excess of the protein concentrations that occur under the operational mite assay conditions. The mite inhibition assay was also reproducible in the presence of non-mite allergen extracts, with and without additional sera containing IgE specific for the non-mite allergens. The binding of a additional sera containing IgE specific for the non-mite allergens. The binding of a constant quantity of mite allergen to the activated solid phase in the direct binding assay was reproducible in the presence of added bovine serum albumin, and of a fungal or arthropod extract, representing the heterogeneous components of an allergen extract at the concentrations of total protein known to occur in the direct binding assay of mite extracts.

Allergens↗