Quantitation of house dust mites and house dust mite allergens in the microenvironment of dogs

OBJECTIVE: To quantitate the density of Dermatophagoides farinae and D pteronyssinus and concentrations of house dust mite (HDM) allergens (Der f 1, Der p 1, and Group 2 allergens) in the indoor microenvironment of dogs. Sample Population-50 homes in Columbus, Ohio. PROCEDURES: n each home, samples of dust were collected from 3 locations in which dogs spent most time. Whenever possible, the species of mites collected was identified. Mite density (mites/g of dust) was assessed, and allergen concentrations were assayed by standardized ELISAs. Relative humidity and temperature in each home were monitored during a 5-day period. Characteristics of homes and sample sources were evaluated. RESULTS: Dust samples from all 50 homes contained > or = 1 HDM allergen; Der f 1 and Der p 1 were detected in 100 and 74% of homes, respectively. Fifteen homes had HDMs; compared with D pteronyssinus, D farinae was found more commonly (14/15 homes) and at a higher density. Basements, homes without central air-conditioning, and dog beds that were > or = 1 year old had high HDM allergen concentrations. Homes with > or = 2 microg of Der f 1 or Group 2 allergens/g of dust or > or = 100 mites/g of dust were significantly more likely to have a maximum relative humidity > or = 75%. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate the presence of HDMs and HDM allergens in the specific microenvironment of dogs in homes. Factors associated with high levels of exposure were identified, which may be associated with increased risk for sensitization and development of atopic diseases.     

Group 1 and 2 Dermatophagoides house dust mite allergens in the microenvironment of cats

House dust mite allergens (HDMAs) are some of the most common allergens associated with allergic diseases in humans and dogs. The purpose of this study was to determine whether HDMAs could be detected in cat‐associated household microenvironments. From 50 cat‐only households with 95 cats, dust samples were collected by vacuuming for 2 min m^?2 from three areas where cats slept or rested regularly from September to October 2006. Relative humidity and temperature were measured in each household using a data logger. Each owner completed a questionnaire on potential factors that might influence the prevalence of house dust mites (HDMs). Dust samples were analysed utilizing an ELISA for Der p 1, Der f 1 and HDM group 2 allergens. In 38 of 50 households there was greater than 2 μg g^?1 of dust for at least one HDMA. Using stepwise logistic regression, factors associated with increased HDMA levels included: free‐standing houses, number of humans in household, longhaired cats and age of the cat. Factors associated with decreased HDMA concentrations included: forced air heating and central air conditioning, less than 50% carpeting of the home, use of flea control, cats suffering from dermatological disease and the average temperature of the household. Many sleeping/resting areas utilized by cats contain sufficiently high levels of HDMAs to be potential sources of sensitization. This finding should lead to further determination of the role of HDMs in cats suffering from putative allergic conditions such as atopic dermatitis or asthma.     

FC-31 Prevalence and characterization of house dust mites and house dust mite allergens collected from the bedding, skin and hair coat of dogs in southwest England

Dust mites (DM) are the most common offending aeroallergens in atopic dogs. The aim of this study was to compare the DM load of households with atopic dogs (Group A, n  = 8) that had positive intradermal test reactions to Dermatophagoides farinae , D. pteronyssinus, Acarus siro, Lepidoglyphus destructor and/or Tyrophagus putrescentiae to the DM load of households with nonatopic dogs (Group B, n  = 4) and of nonpet households (Group C,  n  = 8). Group A dogs presented with perennial pruritus, were free of pathogenic mites and fleas, did not respond to an elimination diet, and fulfilled the diagnostic criteria of atopic dermatitis. All Group B dogs tested intradermally negative and had no dermatological problems. Dust samples were vacuum collected in a standardized fashion from the human (all groups) and dog mattresses (Groups A and B) or from the couch (Group C) four times, once for each season of the year. The presence of DM was assessed with a commercial test (Acarex test) and stereoscopically. At least one DM was found in all Group A houses. The DM load was not significantly different between the seasons or the three animal groups. The sensitivity of the Acarex test was significantly lower than that of stereoscopic examination ( P  < 0.001). In conclusion, the environmental DM load was similar between atopic and nonatopic dogs, the presence of dogs in a household didn't increase DM numbers, and stereoscopy was more sensitive than the Acarex test for the detection of DM.
Funding: Self-funded.     

Quantitation of house dust mite allergens (Der f 1 and group 2) on the skin and hair of dogs

OBJECTIVE: To determine the concentration of house dust mite (HDM) allergens, Der f 1 and group 2, on the skin and hair of dogs and whether associations exist between the presence of Der f 1 and group 2 allergens on the skin and hair of dogs and household and dog characteristics. ANIMALS: 63 pet dogs from 50 homes. PROCEDURE: Dogs were weighed and body surface area in square meters was determined. Skin and hair samples were obtained by vacuuming dogs. Collected dust was analyzed by use of standard ELISA techniques. RESULTS: HDM allergen was detected in 21 of 59 skin and hair samples. Presence of group 2 allergen on skin and hair of dogs was significantly associated with long hair, compared with short or medium length hair. Median house dust sample concentrations of Der f 1 and group 2 allergens were high in homes with dogs that had skin and hair samples that were positive for Der f 1 and group 2 allergens. Dogs with skin and hair samples that were positive for Der f 1 and group 2 allergens resided in homes with a high number of house dust samples that were positive for Der f 1, group 2, or both allergens and in homes with a mean house dust sample allergen concentration of > or =2 microg/g of dust. CONCLUSIONS AND CLINICAL RELEVANCE: Associations exist between environmental HDM allergen concentrations and HDM allergens on the skin and hair samples of dogs. Environmental allergen load is a major factor in accumulation of allergens on the skin and hair of dogs.     

The clinical effect of environmental control of house dust mites in 60 house dust mite-sensitive dogs

Abstract   The purpose of this study was to evaluate the effects of benzyl benzoate, an acaricide for the control of house dust mites, in 60 house dust mite-sensitive dogs. All dogs showed positive reactions on intradermal skin testing for house dust mites ( Dermatophagoides farinae , Dermatophagoides pteronyssinus ) alone, or house dust mites with storage mites ( Acarus siro , Tyrophagus putrescentiae , Glycophagus domesticus ). House dust samples from the owners' houses were collected and sent to the clinic, where the authors performed a test (Acarex® test) to semiquantify the amount of guanine, a house dust mite product. Treatment with benzyl benzoate was repeated until the house dust samples were negative for house dust mite guanine. After treatment, 29 out of 60 house dust mite-sensitive dogs (48%) showed no skin lesions or pruritus. Moderate results were achieved in 22 dogs (36%), with reduced pruritus and minimal skin lesions, but still requiring medication. In 13 dogs, this involved regular treatment (3–4 times a year) with antibiotics and antiyeast medication, and in eight dogs, immunotherapy was used. One dog was controlled with essential fatty acids as monotherapy and one dog was controlled with immunotherapy and essential fatty acids. In the remaining nine dogs (15%), the pruritus remained the same, and these dogs were controlled with oral corticosteroids. These results indicate that house dust mite elimination is a useful tool in the management of house dust mite-sensitive dogs.     

Characterization of house dust mite and scabies mite allergens by use of canine serum antibodies

OBJECTIVE: To identify the major allergenic proteins from the 3 main species of dust mites to which dogs react (Dermatophagoides farinae, D. pteronyssinus, and Euroglyphus maynei) and evaluate the potential cross-reactivity of dust mite allergens with antigens from the ectoparasitic mite Sarcoptes scabiei var canis. SAMPLE POPULATION: Sera from 83 dogs with atopic dermatitis. PROCEDURE: Sodium dodecylsulfate-polyacrylamide gel electrophoresis and immunoblotting using serum from atopic dogs was used to identify IgE-binding proteins in extracts of the 4 mite species. RESULTS: Sera of atopic dogs contained IgE against 23, 17, 25, and 17 allergens from D. farinae, D. pteronyssinus, E. maynei, and S. scabiei, respectively. Unlike the situation for humans, the major allergens for dogs are mostly proteins that are larger than 90 kd molecular weight. Dermatophagoides farinae and E. maynei appear to be more allergenic for dogs than is D. pteronyssinus. Some dogs with serum IgE against dust mites also had IgE against antigens of S. scabiei var canis. CONCLUSIONS AND CLINICAL RELEVANCE: Multiple dust mite allergens induce an IgE response in dogs. These allergens are mostly greater than 90 kd molecular weight.     

Sensitivity patterns to house dust mites and forage mites in atopic dogs: 150 cases

This study investigated intradermal test reactions to extracts of six species of mites in 150 dogs with atopic dermatitis. At least one positive reaction was seen in 120 animals (80%). Dermatophagoides farinae attracted the highest number of positive reactions (108 dogs, 90% of dogs and 72% of atopic dogs showing positive reactions). Positive reactions to other mites were not uncommon, with many dogs testing positive for Dermatophagoides pteronyssinus (32% of dogs tested), Acarus siro (35%), Tyrophagus putrescentiae (30%), Glycyphagus domesticus (27%) and Lepidoglyphus destructor (23%). Sensitivity to D. farinae alone occurred commonly (57% of cases), but multiple sensitivities were seen frequently with the other mites. Cases of sensitivity to only one mite were also seen: D. pteronyssinus (five cases), T. putrescentiae (one case) and G. domesticus (one case). Further studies are needed to appreciate more clearly the precise role played by the different species of mite in canine atopic dermatitis.     

Dermatophagoides mites in house dust as an allergen source in atopic dogs

Thirty dogs with a clinical diagnosis of atopy were skin tested with 58 allergens including an aqueous house dust mite extract and a crude house dust extract. Sixty percent of the dogs had positive skin reactions to both the house dust mite and house dust antigens. In atopic dogs, house dust mites appear to be an important allergen source in house dust extracts but are not the only major source.     

Patch test reactions to house dust mites in dogs with atopic dermatitis

The purpose of this study was to determine the percentage of dogs with spontaneous atopic dermatitis that show a positive patch test reaction to a commercially available 20% house dust mites mixture containing equal parts of Dermatophagoides farinae and Dermatophagoides pteronyssinus in white petrolatum. In addition, we evaluated whether skin reactions induced after the epicutaneous application of house dust mites were clinically and histologically similar to naturally developed skin lesions of dogs with atopic dermatitis. Furthermore, we investigated if the reactions induced by house dust mites were true allergic reactions by comparing them to atopic lesional skin and to patch test reactions induced by an irritant substance (sodium lauryl sulphate). White petrolatum alone and nonlesional skin sites were used as negative controls. Macroscopic and microscopic evaluations of the patch test and control sites were performed in a blinded fashion at 48 and 72 h after patch test application. Microscopic results were evaluated in a qualitative and quantitative manner. A chi‐square test for homogenicity was used for the quantitative analysis to compare the proportion of each dermal inflammatory cell type among positive histopathological tested sites. P values ≤ 0.05 were considered significant. The study included 12 healthy nonatopic dogs and 13 dogs with nonseasonal atopic dermatitis. None of the nonatopic dogs reacted to house dust mites and white petrolatum. Ten (77%) of the 13 atopic dogs reacted macroscopically and histopathologically to house dust mites. Macroscopic reactions induced by house dust mites were characterized by erythema, oedema and papules. The macroscopic reactions induced by house dust mites were identical to lesional skin in 20% of the dogs and identical to reactions induced by sodium lauryl sulphate in 40% of the dogs. Qualitative histopathological findings showed that the reactions induced by house dust mites were similar to atopic lesional skin in 80% of the dogs and were similar to sodium lauryl sulphate in 20% of the dogs. Quantitative analyses showed that the proportion of neutrophils in reactions induced by sodium lauryl sulphate was significantly higher (P < 0.05) compared to house dust mites reactions, which could be a differentiator factor between an allergic and an irritant reaction. These results showed that the epicutaneous application of house dust mites in dogs with atopic dermatitis induced histopathological lesions similar to spontaneous atopic lesions in dogs. Therefore, this study demonstrated that house dust mites penetrated the skin of dogs with atopic dermatitis and induced an inflammatory response that resembled a true allergic reaction. Funding: Small Companion Animal Grant, University of Minnesota.     

Sulphido-leukotriene production from peripheral leukocytes and skin in clinically normal dogs and house dust mite positive atopic dogs

Pathogenesis of canine atopy has not been completely elucidated. In humans, sulphido-leukotrienes (s-LT) play a role in atopy, and increased production of s-LT occurs in the skin and peripheral leukocytes after allergen challenge. The study population included 16 clinically normal and 13 atopic dogs. All atopic dogs had in common a positive reaction (4+) to the intradermal injection of house dust mite (allergen of reference). Blood samples and skin biopsies were collected. Sulphido-LT synthesis by peripheral leukocytes after stimulation was measured, and no statistically significant difference was found between clinically normal and atopic dogs. Sulphido-LT concentrations in skin samples from stimulated and unstimulated sites were measured, and no statistically significant difference was detected between clinically normal and atopic dogs or between lesional and nonlesional skin within the atopic group. Clinical signs of atopic dogs were graded by owners and no correlation was found between their severity and cutaneous concentrations of s-LT. In this study there was no increase in s-LT synthesis in atopic dogs.     

Determination of skin threshold concentration of an aqueous house dust mite allergen in normal dogs

Fifty-six healthy dogs with no known history of atopic disease to indoor allergens were skin tested with 6 different dilutions of an aqueous house dust mite extract. A concentration of 31.25 PNU/ml was found to be the maximum, nonirritating concentration. Thirty-two percent of the research dogs used had to be excluded because they failed to show reactions to any test dilution.     

Evaluation of the presence of house dust mites in horse rugs

A sample of fourteen horse rugs and two saddle blankets stored in south western Sydney, Australia, an area of known high dust mite prevalence in the human environment, were analysed for the presence of house dust mites. Dust samples from the rugs, blankets and 16 control sites were collected using a vacuum cleaner with a modified attachment and filter. Dust mites were extracted using an adapted floatation technique. Eight rugs and all control samples were positive for mites, which were confirmed to be house dust mites of the genus Dermatophagoides. This study confirms that exposure to house dust mites from horse rugs can occur, indicating that house dust mite allergen reactivity on intradermal and serum allergy testing in atopic horses may represent true dust mite hypersensitivity. Nevertheless, quantification studies will be necessary to ensure that there is adequate mite exposure for development of hypersensitivity, and further evaluation of immunological responses, avoidance and provocation, and specific immunotherapy are required to confirm the clinical relevance. To the authors’ knowledge, this is the first study to document the presence of house dust mites in the equine environment.     

Studies on the role of routes of allergen exposure in high IgE-producing beagle dogs sensitized to house dust mites

The current study aimed to investigate the role played by oral, epicutaneous, and inhalation routes of exposure to house dust mites (HDM). The colony of high IgE-producing beagle dogs has been shown to develop pruritic dermatitis compatible with atopic dermatitis following environmental exposure (EE) to HDM. In crossover experiments, the response to EE was compared to two modified challenges, oral exposure (OE) and snood and muzzle exposure (SME). For OE, HDM were fed daily for 3 days. For SME, ingestion of allergen was prevented but there was inhalation and epicutaneous exposure to all body regions except to one ear. In all experiments, dogs were challenged for three consecutive days, and evaluated before, 6 h after exposure and daily thereafter, for 5 days. After a wash-out period, groups were crossed-over so that each dog was randomly challenged to all three protocols. Clinical scores were analysed using least squares analysis of variance. All dogs developed pruritic dermatitis regardless of the protocol. With OE, lesions developed in the same body regions as with EE although scores were lower. This difference became more evident after the first 3 days when OE scores decreased and EE scores continued to increase. The scores of covered and uncovered ears did not differ with SME. Scores for the remainder of the body were significantly lower than for EE. The development of lesions on covered ears supports the importance of inhalation or a systemic reaction to epicutaneous exposure in other areas. It is concluded that all routes are important and have additive effects, that route of exposure does not determine the distribution of lesions and that continuous epicutaneous exposure probably plays the most important role.     

Pilot investigation of a model for canine atopic dermatitis: environmental house dust mite challenge of high-IgE-producing beagles, mite hypersensitive dogs with atopic dermatitis and normal dogs

Although canine atopic dermatitis (cAD) is common, few models are available. The aim of this study was to evaluate high-IgE beagles epicutaneously sensitized to house dust mite (HDM) as a possible model for cAD. Six high-IgE beagles were environmentally challenged with HDM using various doses and protocols. Similar challenge protocols were used in positive and negative control dogs: three dogs with naturally occurring cAD and positive intradermal skin test (IDT) to HDM and three normal dogs without history of skin disease and negative IDT to HDM. All high-IgE beagles and all atopic dogs developed severe cutaneous lesions and pruritus after challenge. Lesions were erythematous papules and macules in contact areas such as face, ears, ventral abdomen, groin, axillae and feet. They were first visible after 6 h and increased in severity over time. No normal dog developed pruritus or lesions. Biopsies of representative lesions in the high-IgE beagles were taken for histopathology and immunohistochemistry. There was superficial perivascular dermatitis with mononuclear infiltrates and spongiosis. Lymphocytes and eosinophils accumulated in small epidermal micro-abscesses with hyperplasia of epidermal IgE-bearing dendritic cells. These findings suggest that this colony of high-IgE beagles develops a dermatitis that clinically, histopathologically and immunologically resembles the naturally occurring canine disease. It is also concluded that this modality of challenge is not irritating to normal dogs but induces flare-ups in hypersensitive atopic dogs.     

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.     

Seasonal dynamics of house dust mites in dust samples collected from sleeping places in north-western Poland

The most common families of mites found in house dust are Pyroglyphidae, Glycyphagidae and Acaridae; all are a source of many antigens responsible for allergic diseases. The aim of this study was to examine the seasonal dynamics of allergenic mite populations in dust samples collected from sleeping places in apartments in north-western Poland. The mites were isolated from the dust using a saturated saline floating method. In 132 dust samples we determined: Dermatophagoides farinae, Dermatophagoides pteronyssinus, Euroglyphus maynei, Hirstia sp., Chortoglyphus arcuatus, Lepidoglyphus destructor, Gohieria fusca and Cheyletus sp. The greatest frequency was observed for D. farinae, D. pteronyssinus, Ch. arcuatus and Cheyletus sp., in the fourth quarter and D. farinae in the third quarter. Smaller coefficients of dominance were found for D. pteronyssinus, Ch. arcuatus and Cheyletus sp., and their greatest mean concentrations were found in the first and fourth quarters. Given the division of the year into heating and non-heating seasons, mites D. farinae and D. pteronyssinus achieved the highest mean concentration in the first season, and Cheyletus sp. in the second season. The analysis of the participation of developmental stages showed that the adults of D. farinae were more prevalent than juveniles in the first, second and third quarters, and imago stages of D. pteronyssinus were more numerous in relation to juveniles in the first, third and fourth quarters. The results confirm the high incidence of house dust mites in sleeping places in north-western Poland dwellings; the best conditions for the development of these mites, mainly D. farinae and D. pteronyssinus, occur in the fourth quarter and are the least favourable in the second quarter. In many cases, these results are consistent with data from other parts of Poland collected by various authors.     

P‐43 IgG antibodies against sarcoptic mite antigens in dogs cross‐reacting with house dust and storage mite antigens

Sera from dogs suffering from scabies were used to evaluate possible antigenic cross‐reactivity with proteins from house dust or storage mites. Polyacrylamide gel electrophoresis on gradient gels was used to create size‐dependent protein bands of Sarcoptes scabiei ssp. vulpis, Dermatophagoides farinae, D. pteronyssinus, Acarus siro, Lepidoglyphus destructor and Tyrophagus putrescentiae. Anti‐canine IgG antibodies conjugated with alkaline phosphatase were used for immunostaining. Different patterns for Sarcoptes could be seen with strong bands repetitively observed of approximately 22, 112, 116, 132 and 200 kD in size. The band at approximately 22 kD seems likely to have cross‐reactivity with a protein of the same size in A. siro. The one at approximately 200 kD might share antigenic activity with bands of D. farinae and, to a lesser extent, D. pteronyssinus. Funding: Laupeneck AG.