DiAnn L. Vyszenski-Moher

Allergenicity of the mite, Blomia tropicalis.

BACKGROUND Blomia tropicalis (BT) occurs in a significant percentage of homes in tropical and subtropical geographic regions of the United States and Europe and in countries in South America and Asia along with the pyroglyphid mites, Euroglyphus maynei (EM), Dermatophagoides pteronyssinus, and D. farinae. Blomia species may be major sources of allergens in house dust in addition to Dermatophagoides species and E. maynei. METHODS Crossed immunoelectrophoresis and crossed radioimmunoelectrophoresis were used to identify the antigens and allergens of BT and to determine the cross-reactivity between BT and the house dust mites, D. farinae, D. pteronyssinus, and the stored product mite, Tyrophagus putrescentiae. RESULTS Homologous crossed immunoelectrophoresis of BT resulted in 27 antigen-antibody complexes. Crossed radioimmunoelectrophoresis of these gels showed 21 different immunoglobulin E binding antigens when they were incubated in the sera from 14 patients with asthma whose radioallergosorbent test and skin test results were positive. Heterologous crossed immunoelectrophoresis reactions with BT and rabbit D. farinae body and feces, D. pteronyssinus body and feces, and T. putrescentiae body and feces antisera resulted in one to four precipitin lines. BT extract, reacted with rabbit antisera produced against the bodies of D. farinae, D. pteronyssinus, and T. putrescentiae, produced 3, 2, and 4 antigenic peaks, respectively; whereas crossed radioimmunoelectrophoresis of these gels with the sera of the 14 patients with asthma resulted in immunoglobulin E binding to 2, 2, and 4 peaks, respectively. CONCLUSIONS The results of this study indicated that BT contained multiple allergens of which most were species-specific. There was a limited amount of cross-reactivity between BT and the two common house dust mite species and the stored product mite. The amount of cross-reactivity appears to parallel the phylogenetic relatedness.

THE DEVELOPMENT OF PROTECTIVE IMMUNITY IN CANINE SCABIES

Seven of eight dogs that had been previously infested with Sarcoptes scabiei var. canis and then cured, expressed protective immunity when experimentally reinfested with scabies. All seven dogs that expressed resistance were spontaneously cleared of scabies by 64 days after they were experimentally reinfested. Five of the eight dogs were free of scabies by 24 days. The sequential changes in the inflammatory/immune cellular infiltrate in the scabietic lesions of each dog were determined during the sensitizing infestation, cure and the subsequent experimental reinfestation (challenge). During the initial infestation and in the subsequent challenge reinfestation, dogs developed mixed cellular infiltrates in their scabietic lesions that contained mononuclear cells, neutrophils, plasma cells and mast cells. Reinfestation induced more rapid increases in the densities of these cells than had occurred during the sensitizing infestation. Mononuclear and mast cells were the most numerous infiltrating cells during the sensitizing phase. During the challenge phase the most numerous infiltrating cells were mononuclear cells and neutrophils. The sensitizing and challenge infestations induced circulating scabies-specific antibody responses, but the response was more rapid during the reinfestation challenge. Both the cell-mediated response in the skin and the circulating antibody response waned in parallel with clearing of the mites following reinfestation.

Acaricidal Activity of Eugenol Based Compounds against Scabies Mites

Backgound Human scabies is a debilitating skin disease caused by the “itch mite” Sarcoptes scabiei. Ordinary scabies is commonly treated with topical creams such as permethrin, while crusted scabies is treated with topical creams in combination with oral ivermectin. Recent reports of acaricide tolerance in scabies endemic communities in Northern Australia have prompted efforts to better understand resistance mechanisms and to identify potential new acaricides. In this study, we screened three essential oils and four pure compounds based on eugenol for acaricidal properties. Methodology/Principal Findings Contact bioassays were performed using live permethrin-sensitive S. scabiei var suis mites harvested from pigs and permethrin-resistant S. scabiei var canis mites harvested from rabbits. Results of bioassays showed that clove oil was highly toxic against scabies mites. Nutmeg oil had moderate toxicity and ylang ylang oil was the least toxic. Eugenol, a major component of clove oil and its analogues –acetyleugenol and isoeugenol, demonstrated levels of toxicity comparable to benzyl benzoate, the positive control acaricide, killing mites within an hour of contact. Conclusions The acaricidal properties demonstrated by eugenol and its analogues show promise as leads for future development of alternative topical acaricides to treat scabies.

Reducing relative humidity to control the house dust mite Dermatophagoides farinae

BACKGROUND Indoor relative humidity (RH) is the key factor that determines the survival and population development of the house dust mite Dermatophagoides farinae. Maintaining RH below 50% is one recommendation in a comprehensive plan to reduce house dust mites and mite allergen levels in homes. Even when mean daily RH is reduced below 50%, RH may rise above 50% intermittently for brief periods because of activities in the home (eg, cooking, bathing, and ventilation). OBJECTIVE The purpose of this study was to determine how brief daily periods of moist air alternating with long spells of low ambient RH (0% or 35%) influence population survival and growth of D farinae. METHODS Population growth was determined for D farinae at daily RH regimens of 2, 4, 6, and 8 hours at 75% or 85% RH alternating with 22, 20, 18, and 16 hours at 0% or 35% RH. RESULTS D farinae populations declined at daily regimens of 2 hours at 75% or 85% RH alternating with 22 hours at 0% or 35% RH. Daily regimens of 4, 6, and 8 hours at 75% RH alternating with 20, 18, and 16 hours, respectively, at 35% RH provided sufficient moisture for small growths in population size. These growths after 10 weeks were reduced by 98.2%, 98.0%, and 97.3% for daily regimens of 4, 6, and 8 hours, respectively, at 75% RH (with the remainder of the day at 35% RH) compared with the growth of populations continuously exposed to 75% RH. Continuous exposure to 85% RH inhibited population growth, but alternating daily regimens of 16, 18, and 20 hours at 35% RH allowed small populations to develop, although they were reduced by 99.4%, 98.8%, and 99.1% compared with population growth at a continuous 75% RH. CONCLUSION This study indicates that maintaining mean daily RH below 50%, even when RH rises above 50% for 2 to 8 hours daily, effectively restricts population growth of these mites and thus the production of allergen. To completely prevent population growth of D farinae, RH must be maintained below 35% for at least 22 hours per day when the daily RH is 75% or 85% for the remainder of the day.

Cross-reactivity between storage and dust mites and between mites and shrimp.

Many patients have sensitivities to multiple species of storage and house dust mites. It is not clear if this is because patients have multiple sensitivities to species-specific mite allergens or if these mites share many cross-reacting allergens. Our objective was to further define the cross-allergenicity between several species of storage and house dust mites using crossed-immunoelectrophoresis (CIE), crossed-radioimmunoelectrophoresis (CRIE), immunoblotting, and ELISA. CIE and CRIE reactions revealed that storage mites shared two cross-antigenic molecules and one of these bound IgE in a serum pool from mite allergic patients. Antibody in anti-sera built to each species of mite recognized many SDS–PAGE resolved proteins of other mite species and this suggested the potential for other cross-reactive allergens. Among patient sera, IgE bound to many different proteins but few had IgE that bound to a protein with common molecular weights across the mite species and this suggested mostly species-specific allergens. Antiserum built to each mite species precipitated one protein in shrimp extracts that bound anti-Der p 10 (tropomyosin) and IgE in the serum pool. Anti-Der p 10 showed strong binding to shrimp tropomyosin but very little to any of the mite proteins. ELISA showed the mite extracts contained very little tropomyosin. The storage and dust mites investigated contain mostly species-specific allergens and very small amounts of the pan-allergen tropomyosin compared to shrimp and snail.

Production of IL-1 alpha and IL-1 beta by human skin equivalents parasitized by Sarcoptes scabiei.

Human skin equivalents (HSEs) were used as a model to investigate interleukin (IL)-1 alpha and IL-1 beta secretions by keratinocytes stimulated by Sarcoptes scabiei (SS). SS mites burrowed into the stratum corneum when placed on the surface of cultured HSEs. Mites lived for 14 days. Mites and mite products induced cells in the HSEs to secrete IL-1 alpha and IL-1 beta within 16 hr. Scabies mites induced production of greater amounts of IL-1 alpha than IL-1 beta. Hepatocyte growth factor in the culture medium at 3 and 30 ng/ml upregulated the secretions of both IL-1 alpha and IL-1 beta by mite-infested skin equivalents, whereas 10 ng/ml of IL-6 upregulated production of only IL-1 beta. Therefore, these cytokines were important immunomodulating factors influencing keratinocyte secretion of IL-1 alpha and IL-1 beta in vitro. The results of this study provide the first evidence that keratinocytes (possibly fibroblasts) in the skin produce these cytokines in response to scabies mites or other ectoparasitic arthropods. Because IL-1 alpha and IL-1 beta are potent inducers of inflammation and keratinocytes are among the first effector cells to encounter scabies mites and their products, these cells may be key initiators of the inflammatory/immune reaction to scabies.

SOME EFFECTS OF SARCOPTIC MANGE ON DOGS

Sequential changes in pathology were examined for scabies-infested dogs to determine the effects of infestation with Sarcoptes scabiei var. canis. During 8 wk of infestation with S. scabiei, the progression of the disease was evaluated weekly by skin scrape, clinical examination, and blood analyses. At 8 wk, selected organs were microscopically examined for histopathology. All infested dogs developed an advanced level of scabies infestation by 8 wk. Of the 36 blood parameters evaluated, only values for erythrocyte sedimentation rate (ESR) deviated significantly from the normal ranges for dogs. However, infested dogs had significantly (P < 0.01) lower average hemoglobin and hematocrit concentrations after 8 wk of infestation compared to their values prior to infestation or to the values for the control dogs. Red blood cell levels for infested dogs dropped significantly (P < 0.01) from preinfestation concentrations by week 8. Conversely, by 8 wk total white blood cell and neutrophil concentrations were significantly (P < 0.01) greater than uninfested controls. Also, whereas average eosinophil concentrations were not statistically different for infested dogs compared to controls, some individual infested dogs exhibited eosinophilia at 4-8 wk of infestation. The ESRs for infested dogs were significantly (P < 0.01) greater at week 6 and 8 than for experimental dogs prior to infestation or control dogs. All parameters except neutrophils had returned to preinfestation levels by 2 wk after treatment for scabies. Neutrophil concentrations were no longer significantly different by 4 wk posttreatment. There were no significant differences in serum enzyme, biochemical and electrolyte concentrations between infested and control dogs.(ABSTRACT TRUNCATED AT 250 WORDS)

HISTOPATHOLOGY IN HOSTS PARASITIZED BY SARCOPTES SCABIEI

Histopathologic evaluation of nondermal tissue in rabbits infested with Sarcoptes scabiei var. canis was investigated. Severe infestation resulted in deviant serological and serum biochemical values. Histological study revealed structural changes in the tissues of specific organs. The most prominent histological finding was amyloidosis in the liver, glomerulus of the kidney, red pulp of the spleen, intestines, and tongue. Hosts treated for infestation exhibited no abnormal organ histology.

Prevalence of serum IgE to storage mites in a southwestern Ohio population

BACKGROUND Storage mites of the families Chortoglyphidae, Glycyphagidae, Echimyopodidae, and Acaridae are commonly found in agricultural and nonagricultural environments. The prevalence of sensitization to these storage mites in the general population in the United States is unknown. OBJECTIVE To determine the prevalence of serum IgE to the storage mites Lepidoglyphus destructor and Acarus siro and to evaluate the degree of co-sensitization to various other astigmatid mites in a population in southwestern Ohio. METHODS Serum samples from 600 people randomly selected from a 1-day submission of approximately 3,000 samples to a clinical diagnostic laboratory were screened for IgE to allergens of L destructor and A siro. Proteins in the extracts of each mite were electrophoretically separated, transferred to membranes, and incubated in the serum samples, and the slot blots were probed for IgE binding using radiolabeled anti-human IgE and autoradiography. RESULTS Thirty-two (5.3%) of the 600 serum samples screened had IgE to allergens from at least 1 of the 2 mite species; 14 (2.3%) and 20 (3.3%) had serum IgE to proteins of the mites A siro and L destructor, respectively. Additional analysis revealed that most serum samples also had IgE that bound to proteins in extracts prepared from a variety of other astigmatid mite species, but IgE binding profiles suggested little cross-reactivity. CONCLUSIONS Sensitization to the mites L destructor and A siro is significant in this region of southwestern Ohio. Further studies are needed to determine the importance of these and other storage mites in occupationally exposed and urban populations of the United States.

Effects of laundry detergents on Dermatophagoides farinae, Dermatophagoides pteronyssinus, and Euroglyphus maynei

BACKGROUND House-dust mites in clothing and bedding are the source of major allergens. Based on studies of Dermatophagoides pteronyssinus only, weekly washing in hot water is recommended to kill dust mites and remove allergens from clothing and bedding. However, in the United States, washing is most often done in warm or cold water, and other mite species are involved. OBJECTIVE The purpose of this study was to investigate the lethal effects of various temperatures of hot water alone and hot, warm, and cold water containing detergents and chlorine bleach on Dermatophagoidesfarinae, D. pteronyssinus, and Euroglyphus maynei. METHODS Mites were soaked in test solutions at various temperatures and for various lengths of time, allowed time to recover, and then analyzed for survival. RESULTS D. farinae was the most temperature-sensitive and chlorine bleach-sensitive of the three species. In 50 degrees C water alone, 100% mortality for D. farinae was obtained in 10 minutes, whereas most D. pteronyssinus and E. maynei survived. However, 53 degrees C-soaks for 12 and 5 minutes were needed to kill all D. pteronyssinus and E. maynei, respectively. Laundry detergents at their recommended and doubled concentrations and chlorine bleach generally increased mite mortalities over water alone for the three species. Soaking for 4 hours in warm water containing various detergents alone induced mortalities of 19 to 50%, 2 to 35%, and 14 to 46% for D. farinae, D. pteronyssinus, and E. maynei, respectively. CONCLUSIONS Washing bed linens weekly in warm water with a 4-hour presoak containing most detergents and bleach will kill most D. farinae and, depending on the detergent brand, moderate numbers of D. pteronyssinus. Four-hour soaks in warm water containing the recommended concentrations of various detergents alone also kills moderate numbers of D. farinae, D. pteronyssinus, and E. maynei. Therefore, the cumulative effect of weekly washing with long presoaks should significantly reduce mite levels over time in bed linens, particularly when mattresses and pillows are encased to prevent reinfestation.