Mite species identification in the production of allergenic extracts for clinical use and in environmental samples by ribosomal DNA amplification

The identification of allergy‐causing mites is conventionally based on morphological characters. However, molecular taxonomy using ribosomal DNA (rDNA) may be particularly useful in the analysis of mite cultures and purified mite fractions in the production of allergenic extracts. Full‐length internal transcribed spacers (ITS1 and ITS2) were obtained from Dermatophagoides farinae, Dermatophagoides pteronyssinus, Dermatophagoides microceras and Euroglyphus maynei (Astigmata: Pyroglyphidae), Glycyphagus domesticus and Lepidoglyphus destructor (Astigmata: Glycyphagidae), Tyrophagus fanetzhangorum, Tyrophagus putrescentiae, Tyrophagus longior, Tyrophagus neiswanderi, Acarus farris and Acarus siro (Astigmata: Acaridae), and Blomia tropicalis (Astigmata: Echymopodidae), using mite‐specific primers. Polymerase chain reaction (PCR) products were digested with HpaII and RsaI restriction enzymes in order to produce species‐specific PCR restricted fragment length polymorphism (RFLP) profiles. A semi‐nested re‐amplification step was introduced before the RFLP in order to apply the method to environmental samples. Results demonstrate that rDNA sequences can be used for the unambiguous identification of mite species. The PCR–RFLP system allows the identification of species in purified mite fractions when the availability of intact adult mite bodies for morphological identification is limited. This reliable and straightforward PCR–RFLP system and the rDNA sequences obtained can be of use in the identification of allergy‐causing mite species.     

Identification of Glycycometus malaysiensis (for the first time in Brazil), Blomia tropicalis and Dermatophagoides pteronyssinus through multiplex PCR

Blomia tropicalis and Dermatophagoides pteronyssinus play an important role in triggering allergy. Glycycometus malaysiensis causes IgE reaction in sensitive people, but is rarely reported in domestic dust, because it is morphologically similar to B. tropicalis making the identification of these species difficult. The identification of mites is mostly based on morphology, a time-consuming and ambiguous approach. Herein, we describe a multiplex polymerase chain reaction (mPCR) assay based on ribosomal DNA capable to identify mixed cultures of B. tropicalis, D. pteronyssinus and G. malaysiensis, and/or to identify these species from environmental dust. For this, the internal transcribed spacer 2 (ITS2) regions, flanked by partial sequences of the 5.8S and 28S genes, were PCR-amplified, cloned and sequenced. The sequences obtained were aligned with co-specific sequences available in the GenBank database for primer design and phylogenetic studies. Three pairs of primers were chosen to compose the mPCR assay, which was used to verify the frequency of different mites in house dust samples (n?=?20) from homes of Salvador, Brazil. Blomia tropicalis was the most frequent, found in 95% of the samples, followed by G. malaysiensis (70%) and D. pteronyssinus (60%). Besides reporting for the first time the occurrence of G. malaysiensis in Brazil, our results confirm the good resolution of the ITS2 region for mite identification. Furthermore, the mPCR assay proved to be a fast and reliable tool for identifying these mites in mixed cultures and could be applied in future epidemiological studies, and for quality control of mite extract production for general use.

     

Seasonal prevalence of allergenic mites in house dust of Kolkata Metropolis,India

During the past few decades, house dust mites have attracted worldwide interest among medical entomologists and acarologists because of their importance in causing nasobronchial allergic disorders in human beings. House dust mites are present throughout the year; however, their relative densities differ in different seasons and habitats. Because the prevalence of house dust mite allergen is important epidemiologically and clinically, detailed knowledge on the seasonal abundance of important allergenic mites is of great importance for better understanding of the pathogenesis of the disease. In view of this, a systematic survey was carried out on the prevalence of total mites and four common allergenic mites in the city of Kolkata for two consecutive years. Both bed and bedroom floor dust were collected separately from homes inhabited by asthmatic patients situated in different corners of the city on monthly basis from January 2004 to December 2005. The population levels of total mites and four common allergenic mites, namely Dermatophagoides pteronyssinus, D. farinae, Austroglycyphagus geniculatus, and Blomia tropicalis separately, were highest during the pre-monsoon period (March–May), irrespective of habitat, whereas densities were low in all cases during winter (December–February). The study indicates that season had the most significant effect on the relative abundance of house dust mites except Dermatophagoides farinae, irrespective of habitat.     

IgE reactivity to Acarus siro extract in Korean dust mite allergic patients

Although specific IgE to the storage mite Acarus siro is often detected, there are no detailed studies on IgE reactivity to A. siro in Korea. This study was undertaken to investigate the cross-reactivity to the mite species Dermatophagoides pteronyssinus, Dermatophagoides farinae, Tyrophagus putrescentiae, and A. siro in Korean mite allergic patients. Specific IgE values were determined for the four mite species and a competitive inhibition test was performed for mite extracts using the ImmunoCAP system. The IgE value to D. farinae was the highest among the four mite species tested. There was a strong correlation in the IgE value between house dust mites (D. pteronyssinus and D. farinae) and between storage mites (A. siro and T. putrescentiae). IgE reactivity to A. siro was inhibited by D. farinae and T. putrescentiae extract. Dermatophagoides farinae extract was the strongest inhibitor of IgE binding to A. siro extract, indicating that IgE reactivity to A. siro extract is a cross-reaction caused by sensitization to D. farinae. Strong IgE reactive components were observed in D. farinae and T. putrescentiae extract by SDS-PAGE and IgE immunoblotting. However, no strong IgE-binding component was observed for A. siro. Dermatophagoides farinae is the main source of mite allergens that cause sensitization in Korea. Serum IgE from some of the house dust mite-sensitized patients showed positive responses to storage mite allergens by cross-reaction. Therefore, it is necessary to pay special attention to the diagnosis of mite allergies.     

Population dynamics of mites of the family pyroglyphidae and micromycetes in laboratory cultures

Original data on the study of the population dynamics in allergenic house dust mites of the family Pyroglyphidae (Dermatophagoides pteronyssinus (Trouessart 1897) and D. farinae Hughes 1961) during long (37 weeks) joint cultivation with the micromycetes Aspergillus penicillioides Speg. in simple periodical cultures without addition of food (SPC) with different initial population density of mites are given. The micromycete A. penicillioides Speg., dominating in laboratory cultures of pyroglyphids, was cultivated in parallel without mites. It was found that during joint cultivation of A. penicillioides and mites, population dynamics of D. pteronyssinus and D. farinae in SPC depended on the initial population density of mites, which affected the duration of mite developmental stages and the degree of the maximal population density. Cultures of D. farinae developed more rapidly than cultures of D. pteronyssinus, independently of the initial population density (50 or 200 specimens per gram of the substrate). A high degree of the initial population density in both mite species resulted in the shortening of the lag-phase, in more rapid reaching of the maximal population density, and in the higher degree of the maximal population density. Population density of the fungus A. penicillioides did not depend on the presence of both mite species. On the basis of our own data and literary analysis, we assume that A. penicillioides can affect the ability of mites to explore the trophic substrate, the rate of the population development, and the degree of their maximal population density. Mites, in their turn, did not significantly affect the development of A. penicillioides in our experiments.     

Toxicity and efficacy of selected pesticides and new acaricides to stored product mites (Acari: Acaridida)

Stored product mites can often infest stored products, but currently there is little information regarding the efficacy of pesticides that can be used for control. In this study we evaluated several common pesticides formulated from single active ingredients (a.i.) or commercially available mixtures (chlorpyrifos, deltamethrin, beta-cyfluthrin, and a combination of deltamethrin and S-bioallethrin), plus an acaricide composed of permethrin, pyriproxyfen and benzyl benzolate, for efficacy against Acarus siro, Tyrophagus putrescentiae, and Aleuroglyphus ovatus. The pesticides were incorporated into the mite diets in a dose range of 10–1000 μg a.i. g⁻¹ diet. Concentrations for suppression of 50 and 90% population growth and eradication (rC₀) of mites were fit to linear regression models. None of the tested pesticides gave complete eradication of A. siro, which was the most tolerant of the three mite species tested. The most effective pesticide Allergoff 175 CS was a combination product (a nano-capsule suspension of permethrin, pyriproxyfen and benzyl benzolate) labeled for dust mites, with rC₀ range of 463–2453 μg a.i. (permethrin) g⁻¹ diet depending on the species. Least effective were chlorpyrifos and deltamethrin.     

Temperature-dependent population growth of three species of stored product mites (Acari: Acaridida)

The pest potential of stored product mites depends on the reproduction rate that is affected by the environmental conditions. In this study we investigated the effect of temperature, ranging from 5 to 35°C, on the population growth of three important mite species, Acarus siro, Tyrophagus putrescentiae and Auleroglyphus ovatus at 85% r.h. Starting with 10 individuals the population increase of mites was observed after 3 weeks of cultivation, or after 6 weeks for those kept at low temperatures (5, 10, 12.5, and 15°C). The rate of increase was calculated for each temperature and species. The obtained data were fitted with polynomial models. The mite population growth rates increased with increasing moderate temperatures until 25°C, when r _m -values were 0.179, 0.177 and 0.190 for A. siro, A. ovatus and T. putrescentiae, respectively. The lower development threshold was 10.2°C in all three species. Estimated upper temperature threshold was higher in T. putrescentiae (49°C) than in A. siro and A. ovatus (38°C). Simulation of the rate of population increase under ideal conditions, using real temperature records obtained from Czech grain stores, showed that the pest mite populations increase only during 3.5 months within a typical 9-month storage season in Central Europe. These results indicate that control of mites, be it chemical, physical or biological, is recommended during the months when allergens and pests are produced, i.e. from September to mid November and in May.     

The importance of starch and sucrose digestion in nutritive biology of synanthropic acaridid mites: α‐Amylases and α‐glucosidases are suitable targets for inhibitor‐based strategies of mite control

The adaptation of nine species of mites that infest stored products for starch utilization was tested by (1) enzymatic analysis using feces and whole mite extracts, (2) biotests, and (3) inhibition experiments. Acarus siro, Aleuroglyphus ovatus, and Tyroborus lini were associated with the starch‐type substrates and maltose, with higher enzymatic activities observed in whole mite extracts. Lepidoglyphus destructor was associated with the same substrates but had higher activities in feces. Dermatophagoides farinae, Chortoglyphus arcuatus, and Caloglyphus redickorzevi were associated with sucrose. Tyrophagus putrescentiae and Carpoglyphus lactis had low or intermediate enzymatic activity on the tested substrates. Biotests on starch additive diets showed accelerated growth of species associated with the starch‐type substrates. The inhibitor acarbose suppressed starch hydrolysis and growth of the mites. We suggest that the species with higher starch hydrolytic activity in feces were more tolerant to acarbose, and α‐amylase and α‐glucosidase of synanthropic mites are suitable targets for inhibitor‐based strategies of mite control. © 2009 Wiley Periodicals, Inc.     

Morphological diagnosis of the eggs of stored-products mites

Eggs of 13 species of common, economically important stored-product pest mites (Acarus siro, A. gracilis, Tyrophagus putrescentiae, T. brevicrinatus, Tyroborus lini, Aleuroglyphus ovatus, Caloglyphus redikorzevi, C. oudemansi, Lepidoglyphus destructor, Glycyphagus domesticus, Aeroglyphus robustus, Chortoglyphus arcuatus and Carpoglyphus lactis) from four families (Acaridae, Glycyphagidae, Chortoglyphidae, Carpoglyphidae) were studied in order to build a diagnostic key. The morphological study dealt with shape, size and surface sculpturing of eggs. Morphological details were visualised using scanning electron microscopy. A key for distinguishing eggs at genus and species level was developed for the major stored-product mites.     

The effects of physical factors on survival of stored food mites

The effects of physical factors (low barometric pressure, high and low temperature, light) on survival of stored food mites (Acaridae: Acarus siro L., Tyrophagus putrescentiae (Schrank), Aleuroglyphus ovatus (Troupeau), Caloglyphus berlesei (Michael); Glycyphagidae: Glycyphagus domesticus De Geer; Carpoglyphidae: Carpoglyphus lactis (L.); Pyroglyphidae: Dermatophagoides pteronyssinus (Troupeau); Cheyletidae: Cheyletus eruditus (Schrank) were studied. C. lactis was the most resistant species-most specimens (85%) of this species survived the longest exposure (96 h) to the lowest pressure (95 mm Hg) tested. It showed 100% mortality only after 80 h exposure to -15°C and it was able to withstand 45°C for about 1 h. Mites from the family Acaridae were killed by low pressure of 95 mm Hg after an exposure of only 48 h and after 1 h exposure to -15°C. Constant light has unfavourable effects on development and reproduction of the flour mite, A. siro.Our results may have some practical implications. Vacuum of 190 mm Hg will protect the food against the mites. Also low temperature -15°C could be used to control mites in seed.     

Enzymatic Activities of Allergen Extracts from Three Species of Dust Mites and Cockroaches Commonly Found in Korean Home

Allergen extracts from dust mites and cockroaches commonly found in Korean homes were used to evaluate their enzymatic activity as they are believed to influence allergenicity. Allergen extracts were prepared from 3 dust mite species (Dermatophagoides farinae, D. pteronyssinus, and Tyrophagus putrescentiae) and 3 cockroach species (Blattella germanica, Periplaneta americana, and P. fuliginosa) maintained in the Korea National Arthropods of Medical Importance Resource Bank. Proteins were extracted in PBS after homogenization using liquid nitrogen. The activities of various enzymes were investigated using the API Zym system. No significant difference in phosphatase, lipase, or glycosidase activity was observed among the 6 allergen extracts, but much difference was observed in protease activity. Protease activity was assessed in more detail by gelatin zymography and the EnzChek assay. Extract from T. putrescentiae showed the highest protease activity, followed by those of the cockroach extracts. Extracts from D. farinae and D. pteronyssinus showed only weak protease activity. Gelatinolytic activity was detected mainly in a 30-kDa protein in D. farinae, a 28-kDa protein in D. pteronyssinus, a > 26-kDa protein in T. putrescentiae, a > 20-kDa protein in B. germanica, and a > 23-kDa protein in P. americana and P. fuliginosa. The information on various enzymatic activities obtained in this study may be useful for future studies. In particular, the strong protease activity found in cockroach extracts could contribute to sensitization to cockroach allergens, which is known to be associated with the development of asthma.     

Distribution and abundance of house-dust mites (Acarina: Pyroglycphidae) in Rome,Italy

For the first time in Rome, house-dust mite infestation was studied in 90 randomly selected houses. In each house, mite infestation was assessed in three sites: mattress, bedroom and living room. In total, 87.8% of the sampled houses were positive for dust mites. In the houses infested, 11.4% showed densities of >100 mites/g of dust, 15.2% registered densities between 50 and 99, and in the remaining houses (73.4%), the densities were between 1 and 49 mites/g dust. The percentages of infested houses were positively correlated with the relative humidity (RH) values (r=0.89,P=0.02). At the lowest range of RH (between 46 and 50), the infestation was 50% and at the highest range of RH (between 73 and 78) it was 100%. The mattress was significantly the most infested (71.1%) of the tested sites. Only wool and spring mattresses were infested, and they did not show any significant differences in mite concentrations.Dermatophagoides farinae was the most abundant species (53.1%), followed byGlycyphagus domesticus (34.5%),D. pteronyssinus (5.2%), andEuroglyphus maynei (0.2%);D. farinae was also the most frequent species (56.9%). The remaining specimens (7.0%) were predator species commonly found in houses. The prevalence ofD. farinae in Rome is discussed.     

<Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> var. <Emphasis Type="Italic">tenebrionis</Emphasis> control of synanthropic mites (Acari: Acaridida) under laboratory conditions

Bacillus thuringiensis (Bt) toxins present a potential for control of pest mites. Information concerning the effect of Bt and its possible application to the biocontrol of synathropic mites is rare. The toxic effect of Bacillus thuringiensis var. tenebrionis producing Cry3A toxin was tested on the mites Acarus siro L., Tyrophagus putrescentiae (Schrank), Dermatophagoides farinae Hughes, and Lepidoglyphus destructor (Schrank) via feeding tests. Fifty mites were reared on Bt additive diets in concentrations that ranged from 0 to 100 mg g⁻¹ under optimal conditions for their development. After 21 days, the mites were counted and the final populations were analyzed using a polynomial regression model. The Bt diet suppressed population growth of the four mite species. The fitted doses of Bt for 50% suppression of population growth were diets ranging from 25 to 38 mg g⁻¹. There were no remarkable differences among species. Possible applications of Bt for the control of synanthropic mites are discussed.     

Combination of the antifeedant bean flour and the predator Cheyletus malaccensis suppresses storage mites under laboratory conditions

Stored product mites are pests of serious economic and medical importance. Recently, it has been shown that the biological control of these pests based on the use of natural compounds and predators had a high potential for success. In this study, we investigated the suppression of three pest mites by combination of the predator Cheyletus malaccensis Oudemans, 1913 and bean flour (Phaseolus vulgaris), which is an antifeedant. Wheat grain (100 g) was contaminated with 100 individuals (Acarus siro (Linnaeus, 1758), Aleuroglyphus ovatus (Troupeau, 1878) or Tyrophagus putrescentiae (Schrank, 1781)). We added bean flour in concentrations of 0, 1, 5 and 10 g kg⁻¹ (wt/wt) and/or the predator with initial predator/prey ratios 0, 1/50, 1/25 and 1/10. The experiment was carried out under abiotic conditions that are optimal for pest development. After 21 days, pest and predators numbers were recorded. Application of flour significantly reduced populations of A. siro, slightly reduced populations of T. putrescentiae, the efficiency increased with increasing concentration. A. ovatus was not affect by bean flour. Populations of all mite species were successfully reduced by the sole addition of C. malaccensis, with a higher efficiency at higher Cheyletus ratios. The additive effect of the predator and flour was mainly apparent in the reduction of T. putrescientae. The population of C. malaccensis was not affected by the presence of bean flour. It is therefore recommended to use bean flour for the reduction of A. siro, a combination of bean flour and Cheyletus for the reduction of T. putrescientae, and only Cheyletus for the reduction of A. ovatus. Handling Editor: Arne Janssen.     

Characterization of a western North American carnivore community using PCR–RFLP of cytochrome <Emphasis Type="Italic">b</Emphasis> obtained from fecal samples

We developed a simple and reliable method to identify carnivore scats to species using PCR and RFLP of a portion of the mtDNA cytochrome b gene, which works for seven of the most common carnivores in western North America. We identified a short (196 bp) polymorphic region of cytochrome b which would be easily amplifiable even from degraded DNA, developed a primer set, and isolated a set of three restriction enzymes (HpaII, DdeI, HpyCH4V) that would identify the seven target species. In order to test whether this protocol would effectively identify scats obtained in the field we collected 243 carnivore scats from 12 sites in the San Francisco Bay area. Eighty five percent (206) of our samples successfully amplified and were subsequently identified to species using our RFLP protocol. We selected 108 of these samples to sequence; our species identifications based on sequencing were identical to those obtained using our PCR–RFLP method. Our PCR–RFLP method is a simple and efficient means to identify carnivore scats to species, eliminating the need for sequencing, which is costly and requires more laboratory equipment. The technique can also be modified depending on the species present at a particular site. It allows for rapid and noninvasive assessment of multiple carnivore taxa and is particularly useful for surveying populations across many sites.     

Interference in foraging behaviour of European and American house dust mites Dermatophagoides pteronyssinus and Dermatophagoides farinae (Acari: Pyroglyphidae) by catmint, Nepeta cataria (Lamiaceae)

The European and American house dust mites, Dermatophagoides pteronyssinus and D. farinae, have a huge impact upon human health worldwide due to being the most important indoor trigger of atopic diseases such as asthma, rhinitis and atopic dermatitis. Preceding studies have shown that the behavioural response of house dust mites towards volatile chemicals from food sources can be assessed using a Y-tube olfactometer assay. In the current study, we used this assay to investigate, for the first time, the ability of the essential oil of the catmint plant, Nepeta cataria (Lamiaceae), known to repel other ectoparasites affecting human and animal health, to interfere with the attraction of D. pteronyssinus and D. farinae towards a standard food source (fish flakes). Two distinct chemotypes (A and B), enriched in the iridoid compounds (4aS,7S,7aR)-nepetalactone and (4aS,7S,7aS)-nepetalactone, and the sesquiterpene (E)-(1R,9S)-caryophyllene, were used. Initial assays with a hexane extract of fish flakes (FF extract) confirmed attraction of mites to this positive control (P < 0.001 and P < 0.05 for D. pteronyssinus and D. farinae respectively), but when presented in combination with either N. cataria chemotype, tested across a range of doses (10, 1, 0.1 and 0.01 μg), decreasing attraction of mites to their food source was observed as the dose augmented. Our study shows that N. cataria, enriched in iridoid nepetalactones and (E)-(1R,9S)-caryophyllene, exhibits potent repellent activity for house dust mites, and has the potential for deployment in control programmes based on interference with normal house dust mite behaviour.     

Identification of house-dust mites

The term house-dust mite usually refers to those species of the mite family Pyroglyphidae, that are known to commonly occur, although sometimes regionally, in the dust of human dwellings. These species belong to five genera:Dermatophagoides, Euroglyphus, Hirstia, andMalayoglyphus. Related species ofDermatophagoides have the most world-wide occurrence, the commonest being:D. farinae, D. microceras, andD. pteronyssinus. A correct taxonomic identification of house-dust mites is very important, not only from a biological stand point, but also regarding the consequences of their respective allergenical properties. Several immuno-chemical studies revealed differences between the products of two hard to distinguish sibling species. A preliminary practical taxonomic key for the most common and important house-dust mites is presented.     

Pollen,mould mites and fungi: improvements to mass rearing ofTyphlodromus doreenae andAmblyseius victoriensis

Populations ofTyphlodromus doreenae Schicha on 18×14 cm arenas using pollen ofTypha orientalis Presl. as food, increased from an estimated 50–150 to 1,000–1,600 motiles per arena in the presence of mould mites,Tyrophagus putrescentiae (Schrank) and the fungusRhizopus stolonifer (Ehrenberg ex. Fr.) Lind.T. putrescentiae in association withR. stolonifer, developed pigmentation and were preyed on byT. doreenae which also became pigmented. UnpigmentedT. putrescentiae were not attacked byT. doreenae which remained pale coloured.T. doreenae died when supplied with the fungus alone. Bean plants dusted with pollen ofT. orientalis from a talcum powder dispenser supported a large population (7–12 stages/leaf) ofAmblyseius victoriensis (Womersley). These improvements to mass rearing ofT. doreenae andA. victoriensis are discussed with respect to their potential for commercialisation.     

Detection of serine proteases in extracts of the domestic mite Blomia tropicalis

Previous studies have shown that the domestic mites Dermatophagoides pteronyssinus and D. farinae contain allergens with serine protease activity. These proteolytic allergens include trypsin, chymotrypsin, elastase, kallikrein, and C3/C5 convertase. However, it is not known whether the domestic mite Blomia tropicalis shares with other mite species the serine protease activities. The enzymatic activity present in extracts obtained from food-free B. tropicalis was investigated using specific substrates and inhibitors. Based upon the concentration response and inhibition profiles, and the digestion of specific substrates our data demonstrate that extracts from B. tropicalis exhibit several serine-protease-like activities. The enzyme activities detected in the B. tropicalis extracts are trypsin, elastase, chymotrypsin, kallikrein, C3/C5 convertase, and mast cell protease. Our results also demonstrate that kallikrein and C3/C5 convertase-like activities were not significantly affected by the α₁-antiprotease, a naturally occurring serine protease inhibitor which protects lung mucosa from the enzymatic action. These data strongly suggest that the Echymyopodidae mite B. tropicalis shares at least five serine proteases with members of other mite families, the Glycyphagidae and Pyroglyphidae. In addition, our data demonstrate the potential use of biochemical methods to detect serine proteases for evaluation of mite growth in vitro, or to detect environmental exposures to these enzymes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of certain socio-ecological factors on the population density of house dust mites in mattress-dust of asthmatic patients of Calcutta, India

Allergy to house dust mites, particularly tothe genus Dermatophagoides is a fairlycommon problem in Calcutta and its adjoiningareas since last two decades. Both the commonspecies of the genus Dermatophagoidesi.e. D. farinae and D.pteronyssinus are found to be abundant in thedust samples collected from beds of patientssuffering from nasobronchial allergic disordes.The presence of these mites in quite a goodnumber in the patients' beds are clinicallycorrelated with the aetiopathology of variousallergic manifestations like bronchial asthma.Dermatophagoides mites may occupydifferent niches in the homes of asthmatics andare more common in beds than elsewhere in thehouse, however, the distribution and abundanceof these mites are influenced by somesocio-ecological factors. The aim and objectiveof the present study is to assess the impact ofsome common socio-ecological managementpractices like the age of house, age ofmattress, type of mattress, frequency ofcleaning of the mattress and even the economicstatus of the patients on the growth,multiplication and finally accumulation ofthese mites in the patients' surroundings.Proper identification of offending allergensand subsequent reduction of load of these miteallergens from the patient's environment may behelpful for the prophylactic management ofthese diseases in Calcutta metropolis.