Localization of Der f 2 in the gut and fecal pellets of Dermatophagoides farinae

Production of Dermatophagoides farinae Having Low Bacterial Content Using Ampicillin

Background

Symbiotic bacteria in house dust mites pose a risk of immunological side effects in the clinical use of immunotherapeutic agents. In this study, we investigated the duration for which the bacterial concentration in Dermatophagoides farinae could be kept low with antibiotic treatment, and whether the allergenic properties of the mite changed under ampicillin treatment.

Methods

D. farinae was cultivated in the presence of ampicillin powder in an autoclaved medium for 6 weeks. After subsequent subcultures without ampicillin, the mites were harvested, and the extract was prepared. The amounts of bacteria, lipopolysaccharides (LPS), and two major allergens (Der f 1 and Der f 2) were measured. Human bronchial epithelial cells and mice were treated with the D. farinae extract to assess the allergic airway inflammation.

Results

The number of bacteria and level of LPS were reduced by 150-fold and 33-fold, respectively, at least 18 weeks after ampicillin treatment. The concentration of Der f 1 and Der f 2 remained unchanged by ampicillin treatment. The secretion of interleukin (IL)-6 and IL-8 from the human airway epithelial cells decreased when treated with the extract of ampicillin-treated D. farinae compared with that of ampicillin-untreated D. farinae. A mouse asthma model was developed using ampicillin-treated D. farinae. We observed that the level of lung function, airway inflammation, and serum-specific immunoglobulin were not different for the mouse asthma model developed using ampicillin-treated D. farinae than the model developed using ampicillin-untreated D. farinae.

Conclusions

We showed that bacterial content in D. farinae was reduced by ampicillin treatment, which was sufficient to induce allergic sensitization and an immune response. This method will be used to develop more controlled allergy immunotherapeutic agents.

Novel Approaches for Inhibiting the Indoor Allergen Der f 2 Excreted from House Dust Mites by Todomatsu Oil Produced from Woodland Residues

House dust mite (HDM) is a globally ubiquitous domestic cause of allergic diseases. There is a pressing demand to discover efficient, harmless, and eco-friendly natural extracts to inhibit HDM allergens that are more likely to trigger allergies and challenging to be prevented entirely. This study, therefore, is aimed at assessing the inhibition of the allergenicity of major HDM allergen Der f 2 by todomatsu oil extracted from residues of Abies Sachalinensis. The inhibition was investigated experimentally (using enzyme-linked immunosorbent assay (ELISA), surface plasmon resonance (SPR), and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)) and in silico using molecular docking. The results showed that todomatsu oil inhibits the allergenicity of Der f 2 by reducing its amount instead of the IgG binding capacity of a single protein. Moreover, the compounds in todomatsu oil bind to Der f 2 via alkyl hydrophobic interactions. Notably, most compounds interact with the hydrophobic amino acids of Der f 2, and seven substances interact with CYS27. Contrarily, the principal compounds fail to attach to the amino acids forming the IgG epitope in Der f 2. Interestingly, chemical components with the lowest relative percentages in todomatsu oil show high-affinity values on Der f 2, especially β-maaliene (-8.0 kcal/mol). In conclusion, todomatsu oil has been proven in vitro as a potential effective public health strategy to inhibit the allergenicity of Der f 2.

Der f 38 Is a Novel TLR4-Binding Allergen Related to Allergy Pathogenesis from Dermatophagoides farinae

It is difficult to treat allergic diseases including asthma completely because its pathogenesis remains unclear. House dust mite (HDM) is a critical allergen and Toll-like receptor (TLR) 4 is a member of the toll-like receptor family, which plays an important role in allergic diseases. The purpose of this study was to characterize a novel allergen, Der f 38 binding to TLR4, and unveil its role as an inducer of allergy. Der f 38 expression was detected in the body and feces of Dermatophagoides farinae (DF). Electron microscopy revealed that it was located in the granule layer, the epithelium layer, and microvilli of the posterior midgut. The skin prick test showed that 60% of allergic subjects were Der f 38-positive. Der f 38 enhanced surface 203c expression in basophils of Der f 38-positive allergic subjects. By analysis of the model structure of Der p 38, the expected epitope sites are exposed on the exterior side. In animal experiments, Der f 38 triggered an infiltration of inflammatory cells. Intranasal (IN) administration of Der f 38 increased neutrophils in the lung. Intraperitoneal (IP) and IN injections of Der f 38 induced both eosinophils and neutrophils. Increased total IgE level and histopathological features were found in BALB/c mice treated with Der f 38 by IP and IN injections. TLR4 knockout (KO) BALB/c mice exhibited less inflammation and IgE level in the sera compared to wild type (WT) mice. Der f 38 directly binds to TLR4 using biolayer interferometry. Der f 38 suppressed the apoptosis of neutrophils and eosinophils by downregulating proteins in the proapoptotic pathway including caspase 9, caspase 3, and BAX and upregulating proteins in the anti-apoptotic pathway including BCL-2 and MCL-1. These findings might shed light on the pathogenic mechanisms of allergy to HDM.

Temperature stress response: A novel important function of Dermatophagoides farinae allergens

Dermatophagoides farinae, an important pathogen, has multiple allergens. However, their expression under physiological conditions are not understood. Our previous RNA-seq showed that allergens of D. farinae were up-regulated under temperature stress, implying that they may be involved in stress response. Here, we performed a comprehensive study. qRT-PCR detection indicated that 26 of the 34 allergens showed differential expression. Der f1 had the most abundant basic expression quantity. Der f 28.0201 (HSP70) and Der f3 had the same regulation pattern in 9 highly expressed transcripts, which only up-regulated at 41 °C and 43 °C, but Der f 28.0201 showed stronger regulation than Der f 3 (19.88-fold vs 6.02-fold). Whereas Der f 1, 2, 7, 21, 22, 27, and 30 were up-regulated under both heat and cold stress, and Der f 27 showed the strongest regulation ability among them. Der f 27 showed more significant up-regulation than Der f 28.0201 under heat stress (23.59-fold vs 19.88-fold), and Der f27 had more obvious up-regulation under cold than heat stress (30.70-fold vs 23.59-fold). The expression of Der f 27, 28.0201 and 1, and D. farinae survival rates significantly decreased following RNAi, indicating the upregulation of these allergens under temperature stress conferred thermo-tolerance or cold-tolerance to D. farinae. In this study, we described for the first time that these allergens have temperature-stress response functions. This new scientific discovery has important clinical value for revealing the more frequent and serious allergic diseases caused by D. farinae during the change of seasons.

Proteomic Analysis Reveals Allergen Variability among Breeds of the Dust Mite Blomia tropicalis

BACKGROUND

The dawn of the "omics" technologies has changed allergy research, increasing the knowledge and identification of new allergens. However, these studies have been almost restricted to Dermatophagoides spp. Although Blomia tropicalis has long been established as a clinically important source of allergens, a thorough proteomic characterization is still lacking for this dust mite.

OBJECTIVE

To increase knowledge of B. tropicalis allergens through proteomic analysis.

METHODS

Eleven in-bred lineages of B. tropicalis were obtained from 11 unique different pregnant females. Their somatic extracts were analyzed and compared with a commercially available extract by liquid chromatography tandem mass spectrometry (LC-MS/MS).

RESULTS

Considerable differences in the protein expression profiles were found among the breeds, and most of them displayed higher expression levels of major allergens than the commercially available extract. Blo t 2 was the most prominent allergenic protein in the analyzed extracts. Six identified allergens and 14 isoforms have not yet been recognized by IUIS. Conversely, 3 previously recognized B. tropicalis allergens were not found.

CONCLUSIONS

The clear impact of inbreeding on allergen content shown by our study leads us to conclude that the quantification and/or identification of allergens from in-bred lines should be routinely considered for mite cultivation in order to select breeds with higher amounts of major allergens. In this sense, LC-MS/MS may be a useful method to achieve this quality control for research and commercial purposes.

Dietary shifts have consequences for the repertoire of allergens produced by the European house dust mite

Products manufactured from mass-cultured house dust mites, currently commercialized for the diagnosis and immunotherapy of allergy, are heterogeneous in terms of allergen composition and thus present concerns to regulatory authorities. The most abundant species, Dermatophagoides pteronyssinus (Trouessart) (Astigmata: Pyroglyphidae), produces 19 allergenic proteins. Many of these are putatively involved in mite digestive physiology and metabolism. This study aimed to evaluate the effects of mite-rearing media on allergen production. Mites were adapted to feed on culture media supplemented with proteins, lipids, carbohydrates or beard shavings, and collected to quantify major allergens (Der p 1 and 2) by immunodetection, transcription of allergen genes by real-time quantitative polymerase chain reaction, and allergen-related enzymatic activities. All culture media significantly affected the content of major allergens. Modification of macronutrients in the diet produced minor effects on the transcription of allergen genes, but significantly altered mite allergen-related activities. The most remarkable impacts were detected in mites feeding on beard shavings and were reflected in reductions in the content of major allergens, alterations in the transcription of nine allergen genes, and changes in eight allergen-related activities. These results demonstrate the importance of culture media to the quality and consistency of mite extracts used for pharmaceuticals, and highlight the need to further elucidate allergen production by mites in the laboratory and in domestic environments.

Detailed two-dimensional gel proteomic mapping of the feces of the house dust mite Dermatophagoides pteronyssinus and comparison with D. farinae: Reduced trypsin protease content in D. pteronyssinus and different isoforms

Major domestic mite allergens are present in feces. We present a detailed 2D-E-MS/MS proteomic analysis of the Dermatophagoides pteronyssinus feces. Precise cultivation yielded a pure fecal extract. We detected differences in fecal allergens/digestive enzymes between D. pteronyssinus and D. farinae using 2D-E fingerprinting, including unique information on species-specific protease isoforms. Proteomic analysis was performed by 2D-E coupled with MALDI-TOF/TOF identification. The species-specific differences in the fecal extracts of the mites were attributed to trypsin-like proteases known as group 3 allergens. In D. farinae, Der f 3 exhibited high abundance with a pI similar (acidic) to that of the cysteine protease Der f 1 and the chymotrypsin protease Der f 6, whereas in D. pteronyssinus, Der p 3 was rarely detected and exhibited low abundance only at basic pI. Moreover, Der p 9 was detected at a pI of ~ 10, in contrast to Der p 1 and Der p 6, suggesting different compartmentalization in the body. Overall, in D. pteronyssinus feces, allergens of groups 1, 2, 6, and 15 were quantitatively similar to those of D. farinae with the exception of the group 3 and 9 allergens. This work provides novel insights into mite-defecated proteins/digestive enzymes, which are important allergens.

SIGNIFICANCE

Millions of people are affected by allergy and asthma, and their number is growing. In homes, the major triggers of allergy and asthma are the house dust mites Dermatophagoides farinae and D. pteronyssinus, and a clear understanding of the development of diseases caused by these mites is needed. The major sources of mite allergens are their feces, which are deposited in the environment and are easily inhaled as part of aeroplankton. However, descriptions of and comparisons between the major fecal allergens of these two mites are lacking. This study shows that similar group 1 (cysteine protease), 2 (NPC2 family), 6 (chymotrypsin) and 15 (chitinase-like) allergens are present in the feces of these two mite species, as determined by 2D-E mapping, whereas group 3 (trypsin) and 9 (collagenolytic protease) allergens in the feces of the two species are different. The results provide unique MS/MS mapped fingerprints of mite species-specific isoforms in feces. The presence of ubiquitin in mite feces suggests that these proteins participate in the post-translational modification of fecal proteins. The findings are essential for understanding differences between D. farinae and D. pteronyssinus with respect to immunoreactivity, protease activation mechanisms, association with microbes, and food utilization.

Two-dimensional gel proteomic analysis of Dermatophagoides farinae feces

Dermatophagoides farinae fecal allergens are a major source of immunogens in home environments; however, as the source of mite fecal allergen is considered spent growth medium extract that can only mimic the pure fecal extract. In this study, we prepared and using proteomic methods analyzed a D. farinae fecal extract for the first time. The preparation approach used D. farinae feces that were produced within 8 weeks of initiating cultivation in minimized growth media. The feces were collected via adhesion to the tissue culture flask surfaces after removing the SGM and mites. This study contains in-depth proteomic mapping of the allergenic isoforms from the D. farinae fecal extract. Despite extensive analysis, MALDI TOF/TOF spectrometry showed that only six proteins/allergens, Der f1, Der f2, Der f3, Der f6, Der f15 and ferritin, originated from D. farinae. No other analyzed proteins were exactly assigned to Dermatophagoides or to similar invertebrate species by sequence similarity. The remaining proteins were assigned mostly to yeasts or cereals (originally dietary proteins); however, many of the proteins were not successfully identified in the current NCBInr. The numerous dietary proteins identified in the feces suggest that these proteins remained highly stable after passing through the gut. Isoforms of the allergens Der f1, Der f3 and Der f15 were identified in more MWs indicating the presence of zymogens and active-enzyme forms. The identified fecal allergens accumulate in the environment during the life of the mite and represent quantitatively greater amounts of mite immunogens than those that were missed in the 2D-E. The results contribute to our understanding of D. farinae digestive physiology with regard to the enzymes/proteins present in the feces.

Influence of the Adjuvants and Genetic Background on the Asthma Model Using Recombinant Der f 2 in Mice

Der f 2 is the group 2 major allergen of a house dust mite (Dermatophagoides farinae) and its function has been recently suggested. To determine the optimal condition of sensitization to recombinant Der f 2 (rDer f 2) in murine model of asthma, we compared the effectiveness with different adjuvants in BALB/c and C57BL/6 mice. Mice from both strains sensitized with rDer f 2 by intraperitoneal injection or subcutaneous injection on days 1 and 14. The dosage was 20 µg. Freund's adjuvants with pertussis toxin (FP) or alum alone were used as adjuvants. On days 28, 29, and 30, mice were challenged intranasally with 0.1% rDer f 2. We evaluated airway hyperresponsivenss, eosinophil proportion in lung lavage, airway inflammation, and serum allergen specific antibody responses. Naive mice were used as controls. Airway hyperresponsiveness was increased in C57BL/6 with FP, and BALB/c with alum (PC200: 13.5±6.3, 13.2±6.7 vs. >50 mg/ml, p<0.05). The eosinophil proportion was increased in all groups; C57BL/6 with FP, BALB/c with FP, C57BL/6 with alum, BALB/c with alum (24.8±3.6, 20.3±10.3, 11.0±6.9, 5.7±2.8, vs. 0.0±0.0%, p<0.05). The serum allergen specific IgE levels were increased in C57BL/6 with FP or alum (OD: 0.8±1.4, 1.1±0.8, vs. 0.0±0.0). C57BL/6 mice were better responders to rDer f 2 and as for adjuvants, Freund's adjuvant with pertussis toxin was better.

The influence of chitin on the immune response to the house dust mite allergen Blo T 12

BACKGROUND

Information about the biological properties of Blomia tropicalis allergens is scarce. It is predicted that Blo t 12, an allergen with two described isoforms, contains a chitin-binding domain, similar to that found in peritrophins. Th2 adjuvant properties have been described for chitin. Therefore, it is feasible that binding to this carbohydrate influences its allergenicity. We aimed to evaluate the chitin-binding activity of Blo t 12 isoallergens and its effect on airway inflammation and antibody responses in a murine model of allergen sensitization.

METHODS

Chitin-binding assays were conducted with the recombinant isoallergens Blo t 12.0101 and Blo t 12.0102. BALB/c mice were sensitized via i.p. with any of the two isoforms (alone, with chitin or alum) and then challenged intranasally. Methacholine-induced bronchial hyperreactivity was tested by whole-body plethysmography and lung sections were stained with hematoxylin and eosin and periodic-acid Schiff. Total IgE and allergen-specific IgE, IgG1 and IgG2 levels were measured by ELISA.

RESULTS

The two isoforms bound chitin, but Blo t 12.0101 showed a stronger binding capacity. Both isoforms induced total and allergen-specific IgE, airway hyperreactivity, bronchial inflammation and mucus secretion without any adjuvant; however, when administered with chitin, Blo t 12.0101 induced higher total IgE levels. The IgG1/IgG2a ratio was significantly higher in mice immunized with Blo t 12.0101 than those immunized with Blo t 12.0102. As peritrophins, Blo t 12 was detected in mite feces.

CONCLUSIONS

Blo t 12 isoforms are chitin-binding proteins that induce airway inflammation and bronchial hyperreactivity. However, for Blo t 12.0101, chitin reinforces its effects on total IgE production.

House dust mite allergy in Korea: the most important inhalant allergen in current and future

The house-dust mite (HDM), commonly found in human dwellings, is an important source of inhalant and contact allergens. In this report, the importance of HDM allergy in Korea and the characteristics of allergens from dust mite are reviewed with an emphasis on investigations performed in Korea. In Korea, Dermatophagoides farinae is the dominant species of HDM, followed by D. pteronyssinus. Tyrophagus putrescentiae is also found in Korea, but its role in respiratory allergic disease in Korea is controversial. The relatively low densities of mite populations and concentrations of mite major allergens in dust samples from Korean homes, compared to westernized countries, are thought to reflect not only different climatic conditions, but also cultural differences, such as the use of 'ondol' under-floor heating systems in Korean houses. HDM are found in more than 90% of Korean houses, and the level of exposure to HDM is clinically significant. About 40%-60% of Korean patients suffering from respiratory allergies, and more than 40% of patients suffering from atopic dermatitis, are sensitized to HDM. Mite allergens can be summarized according to their inherent auto-adjuvant activities and/or their binding affinities to the adjuvant-like substances: proteolytic enzymes, lipid binding proteins, chitin binding proteins, and allergens not associated with adjuvant-like activity. In general, allergens with a strong adjuvant-like activity or adjuvant-binding activity elicit potent IgE reactivity. In Korea, Der f 2 is the most potent allergen, followed by Der f 1. Immune responses are modulated by the properties of the allergen itself and by the adjuvant-like substances that are concomitantly administered with the antigens. Characterization of allergenic molecules and elucidation of mechanisms by which adjuvant-like molecules modulate allergic reactions, not only in Korea but also worldwide, will provide valuable information on allergic diseases, and are necessary for the development of diagnostic tools and therapeutic strategies.

Monoclonal antibodies against recombinant Der f 3 reveal localization of Der f 3 in the gut and faecal pellets of Dermatophagoides farinae

Home dust mite derived materials are known to be a major source of problematic inhalant allergens. The aim of this study was to determine the localization of the group 3 allergen, Der f 3, within Dermatophagoides farinae, in order to assess the relative importance of excreted materials and nonexcreted body components as allergen sources. Recombinant Der f 3 (rDer f 3) was expressed in bacteria and purified as an immunogen for production of monoclonal antibodies (mAb) against it. Dermatophagoides farinae mites and their faecal pellets were embedded in paraffin, and serial sections were immunoprobed with mAb clone 3D3 against Der f 3. D. farinae midgut mucosa, gut contents and faecal pellets were strongly immunopositive for Der f 3. Der f 3 immunoreactive products were not detected in any other internal organs of the mite. These results suggest that Der f 3 allergen may be synthesized in and secreted from the digestive tract and excreted from the mite's body in the faecal pellets.

Household arthropod allergens in Korea

Arthropods are important in human health, which can transmit pathogens to humans, parasitize, or produce important allergens. Allergy prevalence becomes higher in Korea recently as well as other developed countries in contrast to a decrease of infectious diseases. Allergic diseases caused by household arthropods have increased dramatically during the last few decades since human beings spend more their time for indoor activities in modernized life style. Household arthropods are one of the most common causes of allergic diseases. Biological characterization of household arthropods and researches on their allergens will provide better understanding of the pathogenesis of allergic diseases and suggest new therapeutic ways. Therefore, studies on arthropods of allergenic importance can be considered one of the major research areas in medical arthropodology and parasitology. Here, the biology of several household arthropods, including house dust mites and cockroaches, the 2 most well known arthropods living indoor together with humans worldwide, and characteristics of their allergens, especially the research activities on these allergens performed in Korea, are summarized.

Identification of an abundant allergen from the sheep louse, Bovicola ovis

Infestation of sheep with the louse Bovicola ovis is common worldwide and leads to an allergic dermatitis referred to as 'scatter cockle'. IgE from an infested lamb was used in immunoaffinity chromatography to purify allergens from crude preparations of whole B. ovis and its faeces. SDS-PAGE of the affinity-purified eluates from both preparations showed a dominant band with M(r) of 28.5 kDa. Spleen cells from a mouse immunised with B. ovis faecal antigens were used to produce hybridomas which were screened by ELISA to identify those producing monoclonal antibodies (mAb) to the allergens purified by IgE immunoaffinity chromatography. Western blotting demonstrated that all of the mAbs examined recognised the 28.5 kDa allergen. The allergen, purified using immunoaffinity columns constructed with one of the specific mAbs, was shown to cause immediate and late-phase responses on intradermal skin testing in B. ovis-infested but not in naïve lambs. Levels of serum IgE specific for the purified allergen were significantly higher in infested than in naïve lambs (P < or = 0.0025). N-terminal and internal amino acid (aa) sequences obtained from the purified 28.5 kDa allergen were used to design primers to amplify a partial cDNA probe from B. ovis cDNA by PCR. The amplified probe was radiolabeled and used to screen a B. ovis cDNA library. The complete nucleotide sequence of the allergen was determined from the sequences of the positive clones from the library. The full-length cDNA encodes a 255 aa protein including a secretory leader sequence of 26 aas and a mature protein of 229 aas. The encoded protein showed strong homology to several hypothetical proteins of unknown function from diverse species and weak homology with lipid-binding proteins of Xenopus tropicalis and Galleria mellonella. This is the first allergen to be identified from a louse and it has been designated Bov o 1 in accordance with the criteria of the World Health Organization/International Union of Immunological Societies Allergen Nomenclature Subcommittee.

The alimentary canal of Blomia tropicalis (Acari: Astigmata: Echymopodidae): the application of three-dimensional reconstruction technology

The domestic mite species Blomia tropicalis is an important indoor allergen source related to asthma and other allergic diseases in tropical and subtropical regions. Here, we describe the alimentary canal of B. tropicalis with the particular application of three-dimensional reconstruction technology. The alimentary canal of B. tropicalis resembles the typical acarid form consisting of the cuticle-lined foregut and hindgut separated by a cuticle-free midgut. The foregut is divided into a muscular pharynx and an esophagus. The midgut is composed of a central ventriculus, two lateral caeca, a globular colon and a postcolon with two tubiform postcolonic diverticula. The most common cells forming the epithelium of ventriculus and caeca are squamous and cuboidal. The globular cells contain a big central vacuole in the posterior region of the caeca. The epithelium of the colon and postcolon has significantly longer microvilli. The anal atrium is a simple tube with flattened epithelial cells. The spatial measurements of the three-dimensional model suggest that the paired caeca and central ventriculus occupy 55.1 and 34.6%, respectively, of the total volume of the alimentary canal and may play the key role in food digestion.

Localization of Per a 3 allergen in the gut and faecal pellets of the American cockroach (Periplaneta americana)

Cockroach-derived materials are known to be a major source of potent aeroallergens, causing allergic respiratory diseases such as asthma and allergic rhinitis. The aim of this study was to determine the localization of the major allergen, Per a 3 (Cr-PI), within the American cockroach (Periplaneta americana), which might reveal the relative importance of excreted materials and nonexcreted cockroach components as allergen sources. American cockroaches (P. americana) and their faecal pellets were embedded in paraffin, and serial sections were cut and collected on glass slides. After being stained with mouse polyclonal antiserum against Per a 3, the sections were incubated sequentially with biotin-labelled sheep antimouse immunoglobulin G (IgG) and a preformed fluorescent isothiocyanate (FITC)-avidin complex. Finally, the sections were mounted and examined under a fluorescent microscope. Examination of Per a 3 immunoreactivity on the sections of the American cockroaches (P. americana) revealed that the midgut mucosa, gut contents and faecal pellets were all strongly labelled. Per a 3 immunoreactive products were not detected in any other internal organs of the American cockroaches. These results suggest that Per a 3 allergen might be synthesized in and secreted from the epithelia of the midgut mucosa and excreted from the body in the faecal pellets.

Effectiveness of education for control of house dust mites and cockroaches in Seoul, Korea

We evaluated the efficacy of health education in reducing indoor arthropod allergens in Seoul. The mite control measures comprised the use of mite-proof mattress and pillow coverings, regular washing of potentially infested materials, maintenance of a low humidity, removal of carpets, and frequent vacuum cleaning. Cockroach control measures included trapping, application of insecticides, and protecting food. Of 201 homes enrolled in October 1999, 63 volunteers were included in a 2-year follow-up survey between April 2000 and January 2002. Before intervention, the density of mites/g of dust varied greatly; 27.1/g in childrenos bedding, 20/g in adult bedding, 7.2/g on the floors of childrenos bedrooms, 6.8/g in sofas, 5.9/g on the floors of adultos bedrooms, 3.9/g on living room floors, 3.7/g in carpets, and 1.9 mites/g on kitchen floors. The predominant mite species and house percentages infested were; Dermatophagoides farinae 93%, D. pteronyssinus 9%, and Tyrophagus putrescentiae 8%. Comparing 1999 and 2001 infestations, before and after 25 mo of education, mite abundance was reduced by 98%, from 23.7 to 0.57 mites/g of dust. In 1999, cockroaches were detected in 62% homes: 36% Blattella germanica and 35% Periplaneta spp., including 9% double infestations of B. germanica and P. americana. Following intervention, cockroach infestation rates decreased to 22% of houses in 2000 and 23% in 2001. We conclude that continuous and repetitive health education resulted in the effective control of domestic arthropods.