Clinical and immunologic aspects of storage mite allergy

Effects of in-house and commercial extracts of the allergenic mite Tyrophagus putrescentiae on murine and human cell responses

Mites are among the major sources of domestic and occupational allergens worldwide, and continuous exposure to these allergens leads to chronic airway inflammation. One of the most allergenic species is the storage mite Tyrophagus putrescentiae (Schrank). Protein extracts are produced from this mite for tests that help the clinical diagnosis (via prick test), treatment, and monitoring of disease progression in patients who had positive results for allergic reactions. Therefore, the aim of the present study was to evaluate the cell viability of RAW 264.7 and L929 cells when exposed to in-house raw protein extracts of T. putrescentiae compared to a commercial product, as well as quantify TNF-α secretion by RAW 264.7. Additionally, this study quantified the effect of these extracts in IgE secretion in total blood of people affected by this mite. The study found similarity between the in-house extract and the commercial extract as they had equivalent TNF-α secretion. Additionally, viabilities of RAW 264.7 and L929 exposed to the in-house extract were compatible with viabilities of cells exposed to the commercial extract, with no cytotoxicity at the concentrations tested. Results corroborated the hypothesis that the extract produced in-house would be equivalent to the commercial extract in allergic patients when the IgE was quantified. This study is the first to show the cytotoxicity of T. putrescentiae extracts, and to provide a quantitative analysis of TNF-α and IgE.

Suppression function against environmental dust exposure after Dermatophagoides pteronyssinus immunotherapy is associated with production of specific and cross-reactive immunoglobulin G4

BACKGROUND

Whether Dermatophagoides pteronyssinus (Der-p) allergen immunotherapy (AIT) can induce Dermatophagoides farina (Der-f) specific immunoglobulin (sIg) G4 production and tolerance to environmental allergens has not been fully investigated.

OBJECTIVE

We aimed to determine serum Der-p-sIgG4 and Der-f-sIgG4 levels in asthma and/or rhinitis patients undergoing Der-p AIT and their ability to reduce immune responses triggered by indoor-dust extracts.

METHODS

We performed a real-world prospective trial and enrolled patients with allergic rhinitis and/or asthma in Guangzhou, China. These patients received either Der-p AIT (SCIT group) or routine medications (non-SCIT group) for 156 weeks. Clinical outcomes were assessed by the combined symptom medication score (SMS) and FEV₁ % changes. House dust samples were collected to analyze allergen levels. Serum levels of Der-p-sIgG4 and Der-f-sIgG4, serum inhibitory capacity against Der-p, Der-f, and indoor dust extract by sIgE-facilitated allergen binding to B cells (IgE-FAB), and serum blocking indoor dust extract-induced basophil activation inhibition assays (BATI) in peripheral blood monocytes were carried out at weeks 0, 4, 12, 16, 52, 104, and 156 after the initiations of the treatments.

RESULTS

Our study enrolled a total of 60 participants, with 30 patients in each group. Patients in the SCIT group had significantly improved SMS when compared with the baseline and the patients in the non-SCIT group. Median levels of Der-p 1 and Der-f 1 in indoor dust extract were 1.86 μg/g and 4.74 μg/g, respectively. Serum Der-p-sIgG4 and Der-f-IgG4 levels in SCIT patients showed a significant increase from week 12 to week 156. Serum in these SCIT patients could significantly block Der-p, Der-f, and indoor dust extract formation of allergen-sIgE complex and reduced the threshold of IgE-FAB from 16 weeks after the initiation of the treatment. The capacity to inhibit Der-p, Der-f, and indoor dust extract BATI was observed in SCIT serum after 12 weeks. Der-p-sIgG4 and Der-f-sIgG4 had a significant correlation with IgE-FAB and BATI in SCIT patients at all time points.

CONCLUSION

Single Der-p immunotherapy induced both Der-p-sIgG4 and Der-f-sIgG4 production, which might cross-reactively induce tolerance against environmental allergen exposure in patients with asthma and/or rhinitis.

Case report: Tyrophagus putrescentiae (Acari) attacking laying birds in conventional poultry houses

Tyrophagus putrescentiae (Schrank) (Acaridae) is one of the most allergenic mite species worldwide, and it particularly infests household environments, animal feed factories, and food factories. It has been the aim of several studies recently in the healthcare area due to its allergenic potential. However, there had been no records of this species attacking laying birds until this report. This is the first record of adverse reactions in animals triggered by infestations of this species. Therefore, the present study aims at describing the damages and symptomatology of T. putrescentiae infestations on commercial laying hens. Alopecia and dermatitis were symptoms exacerbated by T. putrescentiae infestation starting at 40 weeks old. The presence of this species on hens, as observed in the present study, might be directly related to the accumulation of food and poultry litter on these birds, in their cages, or in the vicinities. Hence, the results might be related to their feeding behavior, which consists of continuous supply of animal feed in these management systems. The present study provides an unprecedented record that reveals the importance and potential for emergency pest status of T. putrescentiae in the poultry industry. Its infestations in poultry houses probably required constant sanitary care and monitoring are required in order to prevent outbreaks of this mite.

Storage mite concentrations are underestimated compared to house dust mite concentrations

Dwellings are increasingly well insulated to save energy and this leads to higher humidity and temperature, which improves conditions for mites. Dermatophagoides antigens are the main allergens involved and tested in atopic asthma. We developed three new species-specific quantitative PCR (qPCR) methods for house dust mites (Dermatophagoides pteronyssinus and D. farinae) and storages mites (Acarus siro, Glycyphagus domesticus, Lepidoglyphus destructor). We sampled dust with electrostatic dust collectors, in the bedrooms, under beds and in the kitchens of patients with allergies (n = 24) and healthy controls (n = 18). Mite quantification was carried out with the three new qPCRs and the qPCR previously described for the Dermatophagoides genus. The qPCRs were highly specific and efficient for house dust mite species and the storage mites. Storage mite concentrations were higher than house dust mite concentrations and were higher in dwellings of patients with allergies. Consequently, allergists should test more often patients against the storage mite antigens by prick tests or IgE serology. Dampness is a major factor in storage mite development and the presence of effective mechanical ventilation can reduce storage mite concentrations four-fold. In addition, to limit exposure to dust mites, treatments should be used throughout dwellings and not only in patients' bedrooms.

Risk of exposure of a selected rural population in South Poland to allergenic mites. Part II: acarofauna of farm buildings

Exposure to mite allergens, especially from storage and dust mites, has been recognized as a risk factor for sensitization and allergy symptoms that could develop into asthma. The aim of this study was to investigate the occurrence of mites in debris and litter from selected farm buildings of the Małopolskie province, South Poland, with particular reference to allergenic and/or parasitic species as a potential risk factor of diseases among farmers. Sixty samples of various materials (organic dust, litter, debris and residues) from farm buildings (cowsheds, barns, chaff-cutter buildings, pigsties and poultry houses) were subjected to acarological examination. The samples were collected in Lachowice and Kurów (Suski district, Małopolskie). A total of 16,719 mites were isolated including specimens from the cohort Astigmatina (27 species) which comprised species considered as allergenic (e.g., Acarus siro complex, Tyrophagus putrescentiae, Lepidoglyphus destructor, Glycyphagus domesticus, Chortoglyphus arcuatus and Gymnoglyphus longior). Species of the families Acaridae (A. siro, A. farris and A. immobilis), Glycyphagidae (G. domesticus, L. destructor and L. michaeli) and Chortoglyphidae (C. arcuatus) have been found as numerically dominant among astigmatid mites. The majority of mites were found in cowsheds (approx. 32%) and in pigsties (25.9%). The remaining mites were found in barns (19.6%), chaff-cutter buildings (13.9%) and poultry houses (8.8%). The results suggest that the allergenic mites may constitute an occupational hazard for agricultural workers in all farming environments examined.

Evaluation of Sensitivity Toward Storage Mites and House Dust Mites Among Nasobronchial Allergic Patients of Kolkata, India

House dust mites (HDMs) are the major constituents of house dust (HD). HD and HDM sensitization is well documented worldwide. Storage mite (SM) sensitization is presently lacking from India. The present study evaluated the sensitization of both HDM and SM among 372 allergic rhinitis patients reported to the Allergy and Asthma Research Center of Kolkata metropolitan, India. HD samples were collected from the patients' home and analyzed for the major constituent mites. HD and six constituent mites Dermatophagoides pteronyssinus (DP), Dermatophagoides farina Hughes (Acari: Pyroglyphidae) (DF), Blomia tropicalis (BT), Acarus siro Linnaeus (Acari: Acaridae) (AS), Lepidoglyphus destructor (LD), and Tyrophagus putrescentiae (Schrank) (Acari: Acaridae) (TP) are tested for the allergenic potential through Skin Prick Test (SPT). Three SMs, namely AS, LD, and TP, were newly included in the mite SPT extract for the first time in Kolkata. In total, 330 patients showed significant positive SPT toward any one allergen tested. HD was the major elicitor exhibiting 92.42% response. Individuals of age group 15-40 were the worst sufferers. DF showed the highest sensitization (87.87%) among the dust mites. The SMs also contributed significantly to prove their sensitizing potential. SPT rates for AS, LD, and TP were 33, 25, and 18%, respectively. SPT grades and total Immunoglobulin E (IgE) were positively correlated for each of the allergens. Most of the patients were multi-sensitized (95%) and represented markedly high total IgE levels (>500 IU/ml). Three SMs proved to be significant allergens for the studied population. The sensitization toward these SMs is first time reported from India and can be recommended for inclusion of routine SPT for better outcome in the future.

[Blomia tropicalis: A house dust mite in the tropics]

INTRODUCTION

Blomia tropicalis is a mite that belongs to the superfamily of Glycyphagidae. Initially described as a storage mite, it is now considered as a house dust mite of tropical and sub-tropical areas.

STATE OF THE ART

Sensitization to this mite is very common in South America and Southeast Asia. Epidemiological studies have also found sensitization to this mite in Africa and Central America. Blo t 5 is the major allergen of B. tropicalis. Co-sensitization to other house dust mites such as Dermatophagoides pteronyssinus (Der p) and Dermatophagoides farinae (Der f) is very common. Cross-reactivity has been described but recombinant allergens revealed by molecular biology techniques do not explain this cross-reactivity. Sensitization to B. tropicalis seems to begin at the age of 36 months, the incidence increases until adulthood, and decreases from the age of 50. The involvement of B. tropicalis in allergic rhinitis and asthma is well described. It is also implicated in other allergic diseases. Few studies have assessed the therapeutic strategies available against this mite but immunotherapy is widely used.

PERSPECTIVES

Studies are needed to better understand the role of B. tropicalis in human diseases and to develop specific treatments.

Allergens of Blomia tropicalis: An Overview of Recombinant Molecules

Allergic diseases are considered a major problem for healthcare systems in both developed and developing countries. House dust mites are well-known triggers of allergic manifestations. While the Dermatophagoides genus is widely distributed globally, Blomia tropicalis is the most prominent mite species in the tropical and subtropical regions of the world. Over the last decades, an increase in sensitization rates to B. tropicalis has been reported, leading to increased research efforts on Blomia allergens. In fact, 8 new allergens have been identified and characterized to different degrees. Here, we provide an overview of recent developments concerning the identification and production of recombinant Blomia allergens, as well as their structural and immunological characterization. Although considerable progress has been achieved, detailed molecule-based studies are still needed to better define the clinical relevance of Blomia allergens. Thus, the establishment of a well-standardized and fully characterized panel of allergens remains a challenge for the development of better diagnosis and therapy of allergic diseases induced by B. tropicalis.

International consensus (ICON) on: clinical consequences of mite hypersensitivity, a global problem

Since mite allergens are the most relevant inducers of allergic diseases worldwide, resulting in significant morbidity and increased burden on health services, the International Collaboration in Asthma, Allergy and Immunology (iCAALL), formed by the American Academy of Allergy, Asthma and Immunology (AAAAI), the American College of Allergy, Asthma and Immunology (ACAAI), the European Academy of Allergy and Clinical Immunology (EAACI), and the World Allergy Organization (WAO), has proposed to issue an International Consensus (ICON) on the clinical consequences of mite hypersensitivity. The objectives of this document are to highlight aspects of mite biology that are clinically relevant, to update the current knowledge on mite allergens, routes of sensitization, the genetics of IgE responses to mites, the epidemiologic aspects of mite hypersensitivity, the clinical pictures induced by mites, the diagnosis, specific immunotherapeutic approaches, and prevention.

Role of Predatory Mites in Persistent Nonoccupational Allergic Rhinitis

Mites can sensitize and induce atopic disease in predisposed individuals and are an important deteriorating factor in patients with allergic rhinitis, asthma, and atopic dermatitis. Although Pyroglyphidae mites have been extensively studied, very scarce reports are available on Cheyletidae spp. especially regarding human respiratory pathology. The main objective of the present study is to investigate the clinical role of this predator mite (Cheyletus eruditus) as a respiratory antigen in a selected sensitized human population. Fifty-two adult patients were recruited from the outpatient allergy clinic to assess their eligibility for the study. The thirty-seven subjects with persistent allergic rhinitis (PAR) who fulfilled the ARIA criteria had a positive IgE response confirmed by skin prick test (SPT) to C. eruditus. Only those individuals (37/47) with a positive SPT to C. eruditus showed a positive nasal provocation test (NPT), while 10 patients with nonallergic mild-to-moderate persistent rhinitis, control group, had a negative NPT with C. eruditus. The present paper describes a new role for the predator mite Cheyletus eruditus as a respiratory allergen in a selected subset of patients in a subtropical environment afflicted with persistent nonoccupational allergic rhinitis.

Feces Derived Allergens of Tyrophagus putrescentiae Reared on Dried Dog Food and Evidence of the Strong Nutritional Interaction between the Mite and Bacillus cereus Producing Protease Bacillolysins and Exo-chitinases

Tyrophagus putrescentiae (Schrank, 1781) is an emerging source of allergens in stored products and homes. Feces proteases are the major allergens of astigmatid mites (Acari: Acaridida). In addition, the mites are carriers of microorganisms and microbial adjuvant compounds that stimulate innate signaling pathways. We sought to analyze the mite feces proteome, proteolytic activities, and mite-bacterial interaction in dry dog food (DDF). Proteomic methods comprising enzymatic and zymographic analysis of proteases and 2D-E-MS/MS were performed. The highest protease activity was assigned to trypsin-like proteases; lower activity was assigned to chymotrypsin-like proteases, and the cysteine protease cathepsin B-like had very low activity. The 2D-E-MS/MS proteomic analysis identified mite trypsin allergen Tyr p3, fatty acid-binding protein Tyr p13 and putative mite allergens ferritin (Grp 30) and (poly)ubiquitins. Tyr p3 was detected at different positions of the 2D-E. It indicates presence of zymogen at basic pI, and mature-enzyme form and enzyme fragment at acidic pI. Bacillolysins (neutral and alkaline proteases) of Bacillus cereus symbiont can contribute to the protease activity of the mite extract. The bacterial exo-chitinases likely contribute to degradation of mite exuviae, mite bodies or food boluses consisting of chitin, including the peritrophic membrane. Thus, the chitinases disrupt the feces and facilitate release of the allergens. B. cereus was isolated and identified based on amplification and sequencing of 16S rRNA and motB genes. B. cereus was added into high-fat, high-protein (DDF) and low-fat, low-protein (flour) diets to 1 and 5% (w/w), and the diets palatability was evaluated in 21-day population growth test. The supplementation of diet with B. cereus significantly suppressed population growth and the suppressive effect was higher in the high-fat, high-protein diet than in the low-fat, low-protein food. Thus, B. cereus has to coexist with the mite in balance to be beneficial for the mite. The mite-B. cereus symbiosis can be beneficial-suppressive at some level. The results increase the veterinary and medical importance of the allergens detected in feces. The B. cereus enzymes/toxins are important components of mite allergens. The strong symbiotic association of T. putrescentiae with B. cereus in DDF was indicated.

Immunoglobulin E-binding epitopes of mite allergens: from characterization to immunotherapy

House dust mites and storage mites produce a number of allergens that can induce hypersensitivity reactions in humans and result in allergic diseases like asthma, rhinitis, and dermatitis. Recent advances in identifying and characterizing these allergens--and, in particular, their immunoglobulin E (IgE)-binding epitopes--have produced a wealth of knowledge. Here, methods for identifying IgE-binding epitopes, from immunoassays to in silico approaches, are summarized and placed in context with the identification of epitopes of mite allergens, particularly from the Dermatophagoides spp. major allergen groups 1 and 2. Finally, the transfer of this information to the clinical development and application of new diagnostic and immunotherapeutic approaches is discussed. While progress in recent years has built on the specific immunotherapies established decades ago, much work remains to be done to mitigate mite allergic disease. Future studies should seek to identify epitopes for mite species beyond Dermatophagoides and for minor allergens. Efforts in translational medicine should use the current epitope data to develop modified allergens for immunotherapy.

House dust mite allergy: environment evaluation and disease prevention

There are two groups of dust mites, house dust mites (HDMs) and storage mites (SMs), that have been identified in the household environment. Both could induce airway inflammation through activation of innate and adaptive immunity and lead to asthma. In order to monitor environmental dust mite infestation, different methods can be used to detect their presence, such as the use of floating methods, monoclonal antibodies, and nanostructured biosensor. SM could be identified in the storage room, mainly in contaminated food such as mushrooms and corn starch. In HDM-sensitive subjects and mice that were challenged with HDM or SM after sensitization, these mites could up-regulate IgE levels, T helper 2 associated cytokine production and airway hypersensitivity. Different age groups of subjects were sensitized by different species of mites. More subjects above 70 years were sensitized by SM and more subjects below the age of 40 years were sensitized to HDM. Different allergenic components of dust mite extracts, such as Der p 1, Der p 2, could activate innate immunity through activating pattern recognition receptor (PRR) and then lead to allergic inflammation. The best modality to treat HDM allergy is immunomodulation through Treg cells and IgA production. In the recent years, many studies indicated probiotics could increase IgA secretion and the number of Treg cells. However, some studies conducted in adults have contradictory effects in reducing allergic symptoms. Therefore, probiotics confer inconclusive benefits on the allergic symptoms.

The efficacy of four avermectins on the synanthropic mite Lepidoglyphus destructor under laboratory conditions

The effect of four avermectins on the population growth of pest mite Lepidoglyphus destructor was tested in laboratory experiments. The avermectins (abamectin, doramectin, emamectin-benzoate and ivermectin) of analytical purity were incorporated into an experimental diet at the same molar concentrations, ranging from 0.16 to 8 nmol/3 g of diet. Using an initial population of 50 mites, the population growth was recorded after 21 days at 85 % relative humidity and 25 °C; 12 repeats were performed per avermectin concentration and control. The diets containing the avermectins successfully suppressed the population growth of L. destructor. The EC(50) recalculated to ng of substance per g of diet showed different suppressive effects of the avermectins: doramectin (181 ng/g diet), abamectin (299 ng/g diet), emamectin-benzoate (812 ng/g diet) and ivermectin (992 ng/g diet). Of the tested avermectins, abamectin is registered for the control of phytophagous mites and ivermectin against parasitic mites, i.e., Psoroptes ovis. Although emamectin-benzoate and ivermectin were less effective on L. destructor, all of the tested avermectins are highly suitable compounds for the control of synanthropic mites.

House dust and storage mite contamination of dry dog food stored in open bags and sealed boxes in 10 domestic households

Dry pet food is a potential source of exposure to house dust and storage mite allergens in canine atopic dermatitis. This study evaluated contamination of house dust and dry dog food stored in paper bags, sealable plastic bags and sealable plastic boxes in 10 households for 90 days using Acarex(®) tests for guanine, a Der p 1 ELISA and mite flotation. Acarex(®) tests were negative in all the food samples but positive in all the house dust samples. The Der p 1 levels and mite numbers significantly increased in food from paper bags (P = 0.0073 and P = 0.02, respectively), but not plastic bags or boxes. Mite numbers and Der p 1 levels were 10-1000 times higher in house dust than the corresponding food samples (P < 0.0001). There were significant correlations between Der p 1 in house dust and food from the paper (P < 0.0001) and plastic bags (P = 0.003), and mite numbers in house dust and food from the paper bags (P = 0.0007). Bedding and carpets were significantly associated with Der p 1 levels in house dust (P = 0.015 and P = 0.01, respectively), and food from the paper (both P = 0.02) and plastic bags (P = 0.03 and P = 0.04, respectively). Mites were identified in six of 10 paper bag, three of 10 plastic bag, one of 10 plastic box and nine of 10 house dust samples. These comprised Dermatophagoides (54%), Tyrophagus (10%; all from food) and unidentified mites (36%). Storage of food in sealable plastic boxes largely prevented contamination for 3 months. Exposure to mites and mite proteins in all the stored food, however, appeared to be trivial compared with house dust.

Sensitization to Dermatophagoides, Blomia tropicalis, and other mites in atopic patients

BACKGROUND

House dust mites (HDMs) are important causes of persistent allergic diseases, such as asthma and rhinitis. Various types of mites are found in the house dust of many countries, including Israel.

OBJECTIVE

To evaluate the prevalence of sensitization to various HDMs in patients with perennial allergic rhinitis and asthma.

METHODS

Sensitization of 117 patients with persistent rhinitis who attended the Allergy and Asthma Center in Tel Aviv (Israel) was evaluated by a skin prick test (SPT) using standardized allergenic extracts. The tested mites were Dermatophagoides farinae (DF), Dermatophagoides pteronyssinus (DP), Lepidoglyphus destructor (LD), Blomia tropicalis (BT), Tyrophagus putrescentiae (TP), Acarus siro (AS), Glycyphagus domesticus (GD), Blomia kulagini (BK), and Tetranychus urticae (TU).

RESULTS

Most patients (n = 95, 81%) had a positive SPT to at least one mite extract. The three most frequent positive reactions were to DF (78%), DP (75%), and, unexpectedly, BT (77%). The correlation between DF and DP sensitization was higher than the correlation between DF or DP to BT (r = .78 versus r = .60, p < .05). Six patients had positive skin reactions to at least one mite species other than DF, DP or BT, mainly LD (n = 2, 2.1%) and BK (n = 4, 3.8%).

CONCLUSIONS

The findings of this study identified the most ubiquitous mites to which Israeli patients with allergic rhinitis were sensitized and indicated the importance of BT as an allergen. Extracts of these mites may provide a more accurate diagnosis and effective treatment of respiratory diseases due to mite allergy in Israel and probably in other countries with similar climes.

Characterisation of Sarcoptes scabiei antigens

In pig herds, the status of Sarcoptes scabiei infections is routinely monitored by serodiagnosis. Crude antigen for ELISA is usually prepared from S. scabiei var. canis or other variations and may lead to variations in the outcome of different tests, making assay standardisation difficult. This study was performed to investigate the antigen profiles of S. scabiei, including differences between hydrophilic and more hydrophobic protein fractions, by Western blotting with sera from pigs with defined infection status. Potential cross-reactivity among S. scabiei (var. canis, suis and bovis), Dermatophagoides farinae and Tyrophagus putrescentiae was also analysed. Hydrophobic S. scabiei antigens were detectable in the range of 40-50 kDa, whilst the hydrophilic fraction showed no specific antigenicity. In the hydrophobic fractions of D. farinae and T. putrescentiae, two major protein fractions in a similar size range could be identified, but no cross-reactivity with Sarcoptes-positive sera was detectable. However, examination of the hydrophilic fractions revealed cross-reactivity between Sarcoptes-positive sera and both the house dust mite and the storage mite in the range of 115 and 28/38 kDa. Specific bands in the same range (42 and 48 kDa) could be detected in blots from hydrophobic fractions of all three tested variations of S. scabiei (var. canis, bovis and suis). These results show that there are considerable differences in mange antibody reactivity, including reactions with proteins from free-living mites, which may interfere with tests based on hydrophilic antigens. Further refinement of antigen and the use of specific hydrophobic proteins could improve ELISA performance and standardisation.

Evaluation of storage mite contamination of commercial dry dog food

Storage mites may be considered important allergens in dogs with atopic dermatitis. High sensitization rates to Tyrophagus, Acarus, and Lepidoglyphus species have been reported in atopic dogs, and dry pet food has been suggested as a potential source of storage mite exposure. The aim of the present study was to evaluate commercial dry dog food for contamination with storage mites, and how storage time and conditions could influence the risk of contamination. Ten different premium commercial dry dog foods formulated for skin disorders were selected. Food bags were opened and stored for 6 weeks under two different environmental conditions. At different time points, samples from each bag were collected and analysed by microscopy, guanine test, storage mite-specific traps, and a modified flotation technique. On opening, two storage mites identified as Acarus siro were isolated from one of the 10 bags by flotation technique, indicating that storage mites can be present in packaged dry dog food bags. After 5 weeks of storage under environmental conditions optimal for mite growth (23.2 +/- 2.1 degrees C and 71 +/- 5.6% of relative humidity), mites were detected by microscopic observation in nine of the 10 diets. When mites were identified by the flotation technique, Tyrophagus spp. were found to be the most common contaminating species. These results show that dry dog food can be a suitable substrate for storage mite reproduction, and that environmental and storage conditions may influence food contamination and mite development.

Assessment of cross-reactivity among five species of house dust and storage mites

In vitro cross-reactivity among two house dust (Dermatophagoides farinae, D. pteronyssinus) and three storage (Acarus siro, Tyrophagus putrescentiae, Lepidoglyphus destructor) mites was examined in 20 mite-sensitive dogs with natural occurring atopic dermatitis (group A), 13 high-IgE beagles experimentally sensitized to D. farinae (group B), and five healthy beagles (group C). Intradermal testing (IDT) and serology for allergen-specific IgE demonstrated that co-sensitization for all possible pairs of the five mites was generally 45% or higher among group A dogs. In the same dogs, enzyme-linked immunosorbent assay cross-inhibition results indicated that each one of D. farinae, A. siro and T. putrescentiae was a strong inhibitor of all the remaining mites, whereas D. pteronyssinus was a strong inhibitor of L. destructor. A high number of positive IDT and serology test results for D. pteronyssinus, A. siro, T. putrescentiae and L. destructor were recorded among group B dogs. No conclusive evidence of exposure to these mites was found upon analysis of dust samples from their environment and their food for the presence of mites and guanine. Also, the number of positive test results was generally higher among group B than among group C dogs. Enzyme-linked immunosorbent assay cross-inhibition revealed that D. farinae was a strong inhibitor of D. pteronyssinus, A. siro and T. putrescentiae. Collectively, these results demonstrated extensive in vitro cross-reactivity among house dust and/or storage mites that can explain false-positive results upon testing of dust mite-sensitive dogs with atopic dermatitis.

Ultrastructure of the digestive tract in Acarus siro (Acari: Acaridida)

The gut of the mite Acarus siro is characterized on the ultrastructural level. It consists of the foregut (pharynx, esophagus), midgut (ventriculus, caeca, colon, intercolon, postcolonic diverticula, postcolon), and hindgut (anal atrium). The gut wall is formed by a single-layered epithelium; only regenerative cells are located basally and these have no contact with the lumen. Eight cell types form the whole gut: (i) simple epithelial cells forming fore- and hindgut; (ii) cells that probably produce the peritrophic membrane; (iii) regenerative cells occurring in the ventriculus, caeca, colon, and intercolon; (iv) spherite cells and (v) digestive cells forming the ventriculus and caeca; (vi) colonic cells and (vii) intercolonic cells; and (viii) cells forming the walls of postcolonic diverticula and postcolon. Spherite and digestive cells change in structure during secretory cycles, which are described and discussed. The cycle of spherite, colonic, and intercolonic cells is terminated by apoptosis. Ingested food is packed into a food bolus surrounded by a single homogeneous peritrophic membrane formed by addition of lamellae that subsequently fuse together. The postcolonic diverticula serve as a shelter for filamentous bacteria, which also are abundant in the intercolon.

Limited IgE cross-reactivity between Dermatophagoides pteronyssinus and Glycyphagus domesticus in patients naturally exposed to both mite species

BACKGROUND

Contradictory results have been found when analyzing the IgE cross-reactivity among pyroglyphid mites and storage mites, as well as the role of these as true sensitizing agents.

OBJECTIVE

We sought to study the prevalence of sensitization to Glycyphagus domesticus in patients naturally exposed to this mite together with the more ubiquitous Dermatophagoides pteronyssinus and the IgE cross-reactivity between them.

METHODS

Mite species present in house dust samples of consecutive patients with mite allergy from Huelva (southwest Spain) were determined by means of light microscopy. Clinical sensitization was assessed by using skin prick and conjunctival provocation tests. Cross-reactivity at the IgE level was studied by using serum IgE determination and inhibition of RAST, IgE immunoblotting, and mite group 2 immunoassays.

RESULTS

After D pteronyssinus, which is present in about 95% of house dust samples, G domesticus was the most important mite and present in about 50% of the samples. Tyrophagus putrescentiae and Lepidoglyphus destructor were detected in third and fourth place, respectively. About half of the patients with G domesticus at home were sensitized to this mite. A low IgE cross-reactivity was observed between D pteronyssinus and G domesticus, but an important IgE cross-reactivity was detected among glycyphagid mites at the level of group 2 allergens.

CONCLUSION

Glycyphagid mites can act as primary sensitizing agents independently of pyroglyphid mites in a subset of patients naturally exposed to them.

CLINICAL IMPLICATIONS

The inclusion of glycyphagid mite extracts in the diagnostic battery in areas with adequate mite growing conditions is important to ensure proper diagnosis.

Comparisons of the allergenic mite prevalence in dwellings and certain outdoor environments of the Upper Silesia (southwest Poland)

The occurrence of allergenic mites (pyroglyphid house-dust mites, acarid and glycyphagid storage mites and others) in dwellings and in synanthropic outdoor sites in a densely populated urban area was investigated. A total of 335 house dust samples were collected from dwellings at 7 different locations in Upper Silesia (Poland), including 84 samples from dwellings of Katowice. Mites were found in 188 of the samples examined (56.1%). A total of 4410 mite specimens were isolated and identified, including 4212 members of the family Pyroglyphidae (95.51%). Among them, Dermatophagoides farinae was predominant (75.3%), followed by D. pteronyssinus (18.6%) and Euroglyphus maynei (1.5%). Moreover, litter soiled with communal wastes was sampled. All 86 samples contained mites. A total of 7547 mite specimens were isolated including 6050 mites known as allergenic (80.5%). Among the astigmatid mites two acarids were dominant: Tyrophagus silvester and T. longior (28.7% and 25.1% of all mites). It should be stressed that 6 of the acarid mite species or genera found in outdoor environments are typical domestic mites (T. putrescentiae), or they have been collected from house dust samples (T. longior, Tyrolichus casei, Thyreophagus entomophagus, Mycetoglyphus fungivorus and Rhizoglyphus robini). The litter of synanthropic sites can therefore form a substantial source of infestation.

House dust and forage mite allergens and their role in human and canine atopic dermatitis

This article reviews the literature regarding the role of house dust and forage mite allergens in canine atopic dermatitis. The presence of immunoglobulin E (IgE) to these mites, especially to Dermatophagoides farinae, is common in both normal and atopic dogs. Exposure of dogs to the different mites is described both in the direct environment and in the coat of animals for house dust mites and in the food for forage mites. Allergens causing allergic disease in dogs seem to be different from those in humans. Dogs seem to react to high molecular weight allergens, compared to the low molecular weight group 1 and group 2 proteases that are commonly implicated in humans with atopic diseases. Despite numerous published studies dealing with this subject, a number of questions still need to be addressed to better understand the exact role of these mites in the pathogenesis of canine atopic dermatitis and to improve the quality of the allergens used in practice.

Skin test reactivity to molds in pre-school children with newly diagnosed asthma

BACKGROUND

The aim of the present study was to evaluate the prevalence of sensitization to molds and to house dust mites (HDM) in pre-school children with newly-diagnosed asthma.

METHODS

From 1996 to 2000, 122 children 1 to 6 years of age with fresh asthma treated in the Kuopio University Hospital, Kuopio, Finland, were recruited in the study; 94% attended. Skin prick tests were performed to common inhalant allergens and to 10 molds. The homes were surveyed for moisture damage.

RESULTS

A majority of the houses had signs of dampness and moisture. One-third of the children reacted to inhalant allergens. There were 11 positive reactions to molds in five children who all reacted to at least one animal dander or seasonal pollen. Aspergillus fumigatus, Botrytis cinerea, and Cladosporium herbarum were the most common mold allergens. There were only two children with positive reactions to HDM, and none of them reacted to molds. No associations were found between the presence or degree of moisture problems at home and mold or HDM allergy.

CONCLUSION

Sensitization to molds seems to play only a minor role in pre-school children with newly-diagnosed asthma in a northern climate where the incidences of mold and HDM allergies are rather low.

Dust mite species and allergen concentrations in beds of individuals belonging to different urban socioeconomic groups in Brazil

BACKGROUND

Dermatophagoides pteronyssinus, Dermatophagoides farinae and Blomia tropicalis dust mites are among the most important agents of hypersensitivity reactions in human beings. However, a role of other mites in the etiology of these reactions has not yet been excluded.

OBJECTIVES

To investigate the nature of the dust mite fauna and the presence of Der p 1 (allergen 1 of Dermatophagoides pteronyssinus) and Blo t 5 (allergen 5 of Blomia tropicalis) on beds used by individuals with different socioeconomic backgrounds in Salvador, a major Brazilian city and to investigate possible associations of mite frequencies and allergen levels with (a) season of the year, (b) housing characteristics, (c) bed cleaning behaviors that could affect mite densities, and (d) allergy history.

METHODS

Dust samples were collected from 459 beds of 101 residences from two groups with different socioeconomic levels (hereafter called wealthy and poor groups) in the city of Salvador, Brazil, for the identification of mite species and determination of Der p 1 and Blo t 5 levels. History of allergy was collected using the ISAAC phase I questionnaire.

RESULTS

Eighty nine percent of the beds analyzed harbored at least one mite species. B. tropicalis was found in 71.8%, D. pteronyssinus in 39.9%, Cheyletus sp. in 33.9%, and Gohieria fusca in 21.1% of the beds. B. tropicalis was found with a similar frequency in beds of the two socioeconomic groups; D. pteronyssinus was found more frequently in the beds of the wealthy than of the poor group, whereas the reverse was observed with G. fusca. The concentrations of Der p 1 and Blo t 5 allergens exceeded the cut-off for sensitization of 2 microg/g of dust in 94.0% and 69.3% of the wealthy and poor group beds, respectively. No associations were found between history of allergy and mite species or between history of allergy and the concentrations of mite allergens.

CONCLUSIONS

The observation of B. tropicalis and D. pteronyssinus as the most frequently found mites is consistent with previous reports from tropical regions. The higher frequency of G. fusca in beds of individuals from the poor group than those from the wealthy group could be a consequence of different bed cleaning behaviors between the two groups.

Comparison of communities of stored product mites in grain mass and grain residues in the Czech Republic

In storage facilities one can find grain either in stored grain mass or in grain residues in the store corners or machinery. Although it is claimed that grain residues are serious pest reservoirs since they harbor numbers of stored product arthropods and are connected via continuous emigration with grain mass, the documentation for this is not convincing. Therefore in 78 selected grain stores, we simultaneously sampled the grain mass and residues in order to compare concurrent mite communities in these two different habitats. We found 30 species in about 614,000 individuals in residues and 23 species in about 20 000 individuals in grain mass. Canonical correspondence analysis (CCA) of transformed abundance data showed differences in the communities of mites in grain mass and residues: (i) species associated to grain residues (e.g. Tyrophagus longior, Tydeus interruptus, Acarus farris and Cheyletus eruditus) and (ii) species associated to both grain mass and grain residues (e.g. Tarsonemus granarius, Acarus siro, Tyrophagus putrescentiae, Lepidoglyphus destructor and Cheyletus malaccensis). Although the residue samples had more mites and higher species diversity than the stored grain mass, no correlation in mite abundance and species numbers between samples from grain residues and grain mass was found, thereby indicating low connectivity of these two habitats.

Occupational rhinitis: diagnostic criteria, relation to lower airway symptoms and IgE sensitization in bakery workers

CONCLUSIONS

The use of different diagnostic criteria has considerable consequences for the prevalence estimates of occupational rhinitis. There is a strong relationship between occupational rhinitis and lower airway symptoms. Storage mites appear to be important occupational allergens in Norwegian bakeries.

OBJECTIVES

To study the consequences of various diagnostic criteria on the prevalence of occupational rhinitis, assess the prevalence of IgE sensitization and explore the relationships between upper and lower airway symptoms and between symptoms and IgE sensitization.

MATERIAL AND METHODS

A total of 197 employees in 6 bakeries were interviewed and completed a questionnaire. A skin prick test was performed, total and specific IgE were determined and a histamine release test was performed for relevant allergens. The criteria for the diagnosis of occupational rhinitis were based on the 1994 International Consensus Report on Rhinitis.

RESULTS

The prevalence of occupational rhinitis varied between 23% and 50%, depending on the criteria used. The occurrence of nasal symptoms was found to precede the development of lower airway symptoms. Occupational rhinitis, both IgE- and non-IgE-mediated, was associated with asthma symptoms. The most frequent causes of sensitization (20%) were different species of storage mites. Storage mite sensitization was related to occupational rhinitis and work exposure.

Intradermal testing with the storage mite Tyrophagus putrescentiae in normal dogs and dogs with atopic dermatitis in Colorado

The purpose of this study was to evaluate reactions to intradermal injections of Tyrophagus putrescentiae extract in healthy dogs and dogs with atopic dermatitis and to compare the prevalence of positive reactions in the two groups. Twenty-one healthy dogs and 26 atopic dogs were tested intradermally with T. putrescentiae extract at 1000, 500, 250, 125, 63, 32 and 16 PNU/mL. Reactions were evaluated objectively and subjectively. A Mann-Whitney test was used to determine differences in grade of reaction to storage mites between healthy dogs and dogs with atopic dermatitis. Positive reactions to storage mite extract were most common at 1000 PNU/mL with approximately one third of normal and atopic dogs showing a positive reaction to T. putrescentiae. There was no significant difference in the incidence of positive reactions between normal and atopic dogs for any of the Tyrophagus extract concentrations.

Prevalence of house dust mites and dermatophagoides group 1 antigens collected from bedding, skin and hair coat of dogs in south-west England

The house dust mites Dermatophagoides farinae (Df) and D. pteronyssinus (Dpt) are commonly implicated as allergens causing canine atopic dermatitis in the UK. However, there are few studies that characterize the exposure of UK pet dogs to these mites. The objectives of this study were to determine the prevalence of the mite species on the skin, hair coat and bedding of a population of pet dogs. Dust samples (n = 68) were collected from both dogs and their beds using a standardized vacuuming technique and stored at -20 degrees C. Mites were identified using accepted morphological criteria. House dust mite allergen concentrations were assayed using standardized ELISA for Dpt and Df group 1 allergens (Der p 1 and Der f 1). Mites were identified in 15/68 samples (22%) and Dpt was the most common. Df mites were not present. Der p 1 allergens were detected in 60% of samples, and Der f 1 in 6% of samples. There were no significant differences between the number of Der p 1 positive samples from dogs and the number of those from their bedding, or between the average Der p 1 concentrations from dogs and the number of those from their bedding. Contrary to studies elsewhere in Europe and the USA, these findings support studies of human asthma patients in the UK, where exposure to Df is rare, but to Dpt is common. As the prevalence of positive intradermal and serological reactions to Df in atopic dogs is high, further investigations are warranted to clarify true Df hypersensitivity or potential immunological cross-reactivity between mite allergens.

[Exposition and sensitization to Tyrophagus putrescentiae in a allergic population to Dermatophagoides pteronyssinus in Huelva, Spain]

BACKGROUND

In this work we analyzed the allergological importance of Tyrophagus putrescentiae (Tp) in Huelva (SE Spain). We studied the level of exposition and the grade of sensitization to Tp in a group of patients sensitized to Dermatophagoides pteronyssinus (Dpt). The allergenic cross-reactivity between Dpt and Tp was determined by RAST inhibition.

METHODS AND RESULTS

We analyzed house dust samples from the dwellings of allergic patients with documented Dpt sensitization. Skin test (ST), conjunctival provocation (CP) and/or specific IgE (RAST) to Tp were performed when Tp was identificated in the house dust sample of the patient. Among the 136 dust samples studied, Dpt was the most frequently identified mite species (94.8%) and Tp was found in third position (41.1%) after Glycyphagus domesticus (54.4%). Among the 45 patients studied, 23 (51.1%) presented, at least, two positive tests, 18 (40%) were not sensitized to Tp and 4 (8.8%) showed contradictory results. 26 patients (57.7%) inhabited in urban areas and 19 (42.2%) in rural regions. We determined specific IgE (RAST) to Tp in 25 patients, and the results were positive in 12, with only 7 with values greater than 2 kU/L. No significant correlation were found between IgE-antibody levels to Dpt and Tp. The RAST inhibition studies confirmed the low cross-reactivity between these mites and only in one patient Dpt partially inhibited the IgE-binding to Dpt extract.

CONCLUSIONS

Tp was the second more frequent storage mite in the house dust samples from patients allergic to Dpt in Huelva. However, only half of the exposed patients were sensitized to Tp and the majority inhabited in urban areas. No significant correlation were found between IgE-antibody levels to Dpt and Tp. The RAST inhibition studies confirmed the low cross-reactivity between these mites.

Allergenic composition of the mite Suidasia medanensis and cross-reactivity with Blomia tropicalis

BACKGROUND

Mites of the genus Suidasia are commonly found in house dust and may play an allergenic role in exposed populations. However, the allergenic potential and clinical impact of this genus has not been well established. The main objective of this project was to evaluate the allergenic role of the mite Suidasia medanensis.

METHODS

An extract of S. medanensis was prepared and the allergen composition determined by immunoblot. Specific IgE antibody levels to S. medanensis and Blomia tropicalis were evaluated by radioallergosorbent (RAST) in the sera of 97 allergic asthmatic patients and 50 nonallergic subjects. Cross-reactivity between S. medanensis and the mite species B. tropicalis and Dermatophagoides farinae was investigated by RAST and immunoblot inhibitions.

RESULTS

Seventy-one asthmatic patients sera (73.2%) had positive IgE reactivity to S. medanensis; 14 allergens with molecular weights ranging from 7.5 to 105 kDa were detected. The most frequently detected had molecular weights of 30-31 (54.8%), 24.5 (42%), 21 (38.7%), 47 (35%) and 58 kDa (35.5%). Blomia tropicalis extract inhibited IgE binding to nine of these identified allergens. Four B. tropicalis allergens were inhibited by S. medanensis extract. RAST inhibition results demonstrated a high degree of inhibition by B. tropicalis (87.2%) and D. farinae (90.9%) than by S. medanensis (32%).

CONCLUSIONS

Sensitization to S. medanensis is common in asthmatic allergy patients in Cartagena. An important degree of cross-reactivity was established between S. medanensis and B. tropicalis, and D. farinae.

Proteolytic activities in body and faecal extracts of the storage mite, Acarus farris

Trypsin, chymotrypsin, cathepsins B and D, aminopeptidase and carboxypeptidases A and B were detected in body extracts of the storage mite Acarus farris (Oudemans) (Astigmata: Acaridae). Faeces-enriched medium exhibited higher (10-50-fold) specific protease activity rates than those measured with mite body extracts for trypsin, chymotrypsin and carboxypeptidases A and B, suggesting that they are involved in mite digestion. However, the activity of cathepsin B was only three-fold higher in faecal than in body extracts, indicating that its presence in the lumen of the digestive tract is low compared to that of serine proteases. The activity of aminopeptidases was higher in mite bodies, indicating that they might be membrane bound. Cathepsin D activity was only detected in body extracts, indicating that this enzyme is not a digestive protease in this species. Zymograms resolved three major bands of gelatinolytic activity, but at least one protease form was only present in body extracts. Protease inhibitors of different specificity were tested in vivo to establish their potential as control agents. The development of A. farris was significantly retarded when the immature stages were fed on artificial diet containing inhibitors of serine and cysteine proteases and aminopeptidases, whereas no such effect was found with inhibitors of aspartyl proteases and carboxypeptidases. Interestingly, the most significant effects on A. farris occurred when a combination of inhibitors targeting different enzyme classes was supplied mixed in the diet, suggesting a synergistic toxicity. Several plant lectins were also tested, but only wheat germ agglutinin and concanavalin-A affected development.

High prevalence of storage mite sensitization in a general adult population

BACKGROUND AND AIM

Occupational and nonoccupational storage mite (SM) allergy has received considerable attention in recent years. The study aimed to evaluate both the prevalence and factors associated with sensitization to SMs in a general adult population from a warm and humid area where mites are the predominant allergens.

PATIENTS AND METHODS

An age-stratified random sample of 720 subjects was drawn from the population older than 18 years of A-Estrada (Galicia, Spain). From 697 eligible subjects, 469 (67%, median age 54 years, range 18-92 years, 44% males, 75% of cases from a rural environment) agreed to participate. Skin prick tests to SMs (Lepidoglyphus destructor and Tyrophagus putrescentiae), house dust mite (Dermatophagoides pteronyssinus), pollens, moulds and animal danders were performed in all cases. Wheals >or= 4 mm were considered positive. Epidemiological data were assessed by questionnaire. A design-based analysis was performed and all calculations were weighted to give unbiased estimates.

RESULTS

Tyrophagus putrescentiae and L. destructor were the leading causes of allergic sensitization throughout all ages. SM sensitization was found in 104 cases (weighted value 24.4%, 95% CI 20.6-28.2). SM sensitization was inversely associated with age. Multivariate analysis showed that SM sensitization was not significantly associated with sex, smoking, educational level, farming profession, rural environment, indoor humidity, presence of pets, livestock or grain storage facilities near home.

CONCLUSIONS

SMs (T. putrescentiae and L. destructor) are major aeroallergens in adults in the region studied, even in subjects without occupational exposure.

Comparison of intradermal and serum testing for allergen-specific IgE using a Fcepsilon RIalpha-based assay in atopic dogs in the UK

Atopic dermatitis in dogs is a common allergic skin disease that affects substantial numbers of dogs in the UK. The purpose of this study was to compare the results of an intradermal test (IDT) and an in vitro test in a large cohort of dogs. Dogs were intradermal tested with Greer allergens (Greer Labs Inc, Lenoir, NC, USA) using standard techniques. At the same time blood samples were drawn and submitted for evaluation by ELISA using the ALLERCEPT Definitive Allergen Panels for allergen-specific IgE, a commercial assay that uses a biotinylated recombinant extracellular domain of the high affinity Fc-epsilon receptor alpha chain protein (Fcepsilon RIalpha). The allergens used in the two tests included grass, tree and weed pollens, moulds, flea saliva/whole flea extract and house dust mite species. The optical density readings from the ELISA for each allergen were compared with the results of the IDT for 265 dogs. The prevalence of positive reactions in the ELISA was equal to or greater than the results of the IDT in the case of almost all of the allergens, but two notable exceptions were the house dust mites Dermatophagoides farinae and Dermatophagoides pteronyssinus. These two allergens were the most common positive reactions by IDT (prevalence D. farinae 78.9%, D. pteronyssinus 66.4%). The results of the two tests were significantly different (McNemar's test, P<0.05) for 16 of the 22 allergens. The sensitivities of the ELISA compared to the IDT (where there were more than 3 dogs with positive reactions in both tests) varied between 19.3 and 77.1% (D. pteronyssinus 19.3% and D. farinae 67.9%) and the specificities varied between 64.2 and 96.6% (D. pteronyssinus 96.6% and D. farinae 89.3%).

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 (χ² = 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 (χ² = 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 (χ² = 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.

Evaluation of nebulised hay dust suspensions (HDS) for the diagnosis and investigation of heaves. 1: Preparation and composition of HDS

Currently, heaves is investigated by exposing susceptible horses to dusty hay. Consequently, the response will be dependent on the organic dust content and composition of the hay. It was hypothesised that the use of a hay dust suspension (HDS) would reduce the variability of the challenge and therefore standardise experimental protocols. Furthermore, analysis of HDS would also permit further investigation of the organic dust components responsible for the response. Three hay dust suspensions (HDS-1, 2 and 3) were prepared for use in the diagnosis and investigation of heaves. HDS were produced from fine dust particles, comprising mostly fungal spores, collected from 3 batches of dusty hay. HDS-1 and 3 were analysed for endotoxin, beta-D-glucan and protein concentrations, general protease activity and enumeration and size distribution of particulates. Protease activity was mainly attributable to a 28 kDa serine protease and to 85 kDa and 160 kDa metalloproteases. The particulate and soluble components of HDS could be aerosolised by jet nebulisation. We therefore conclude that detailed analysis of HDS is possible, that such a challenge system provides a method of standardising experimental protocols and that all components of HDS (both soluble and particulate) can be delivered to the lung using standard nebulisation techniques. For the above reasons, nebulised HDS offers considerable advantages over conventional hay/straw challenge for the diagnosis and investigation of heaves.

Arthropod allergens and human health

Many species of arthropods are the sources of potent allergens that sensitize and induce IgE-mediated allergic reactions in humans. Most of these arthropod allergens are proteins, and the allergic response mechanism to these allergens is the same as it is for allergens from other sources such as plant pollens, molds, and foods. Aside from ingestion of crustaceans (shrimp, lobster), among arthropods, humans have the greatest contact with insects and mites, and as a result allergies to these two groups of arthropods have been the most frequently reported. Because of the large number of people affected by allergic reactions to stinging insects, cockroaches, and dust mites, many allergens of these organisms have been extensively studied, purified, and immunobiochemically characterized and for some recombinant allergens, produced. Cocktails of these recombinant allergens have the potential for use in diagnosis and immunotherapy. In this chapter, we review the insects and mites that induce allergic reactions. Where the information exists, the immunobiochemical characterization of the allergens and the frequency of sensitivity or clinical reactivity in the human population are also reviewed. As background, the beginning of this review includes sections that define allergens, explain the allergic reaction mechanism, and describe the methods for naming allergens.

Dust mites: update on their allergens and control

Mites are ubiquitous organisms, and as a result, humans come into contact with mites and mite products in a variety of situations. Molecules from many mite species can induce IgE-mediated reactions. Best known among the allergy-causing mites are the house dust and storage mites. However, allergists should be aware that, in specific situations, contact with products of many other less-known species of mites also may cause IgE-mediated reactions.

Allergenic cross-reactivity between the nematode Anisakis simplex and the dust mites Acarus siro, Lepidoglyphus destructor, Tyrophagus putrescentiae, and Dermatophagoides pteronyssinus

BACKGROUND

The nematode Anisakis simplex is a common parasite on fish and other seafood. It is considered to be a food allergen and to induce IgE-mediated reactions. Allergenic cross-reactivity between A. simplex and other nematodes has been reported, as has cross-reactivity with arthropods: red mosquito larvae and German cockroach. We have here studied the allergenic relationship between A. simplex and four different dust-mite species.

METHODS

Serum samples collected from 69 farmers allergic to dust mites were analyzed for IgE to A. simplex by CAP FEIA. Allergenic cross-reactivity between A. simplex and dust mites was studied in two of the sera by CAP FEIA and immunoblotting inhibition.

RESULTS

We found that 14/69 farmers had detectable levels of IgE antibodies to A. simplex. The IgE response in CAP FEIA to A. simplex was inhibited to various degrees in the two studied sera by extracts of the dust mites Acarus siro, Lepidoglyphus destructor, Tyrophagus putrescentiae, and Dermatophagoides pteronyssinus. In the reverse inhibition experiment, extract of A. simplex inhibited the response in both sera to A. siro and T. putrescentiae, but not to L. destructor. The IgE binding to D. pteronyssinus was inhibited in one of the two sera. In blotting inhibition experiments, the IgE binding to several allergens in A. simplex was inhibited by each of the four mite extracts, especially by A. siro and T. putrescentiae, which completely inhibited the IgE binding to several allergens.

CONCLUSION

The results show allergenic cross-reactivity between several allergens in A. simplex and four dust-mite species. The clinical significance of this cross-reactivity remains to be evaluated.