Dissertations / Theses on the topic 'Mites and fungi in house dust'

Mites are endemic and allergy to mite excreta and parts is one of the most common allergies. Health care practitioners have recommended the removal of carpets from homes of people with mite allergies. Little, if any, consideration is given to the fact that some persons may benefit directly from the presence of carpet in their homes. In the allergen and mite research literature, carpets are rarely described as having unique characteristics and are generally referred to as a generic entity. Carpets, however, do have unique characteristics that define their construction, appearance, wearability, and cleanability. Seventy-two pieces of commercially available, residential flooring materials were inoculated with identical numbers of mites, Dermatophagiodes farinae, and placed in the Textiles Conditioning Lab at Virginia Tech. The mites and carpet pieces were maintained in the lab, under identical, environmentally controlled conditions for 6 weeks, then the mites were extracted and counted. On the basis of the results of statistical tests run on the study data, the null hypothesis, that there is no difference between the numbers of mites grown on the different flooring conditions, was rejected. Statistically significant differences exist between the hard floor and the nylon carpet, between hard floor and olefin carpets, but no difference between hard floor and wool carpet. Nylon was the carpet fiber that was most supportive of the growth of house dust mites, olefin was the second most supportive, and wool carpet and hard floor were similar in being the least supportive.
Master of Science

Thesis (M.A.)--West Virginia University, 2000.
Title from document title page. Document formatted into pages; contains viii, 123 p. Includes abstract. Includes bibliographical references (p. 63-68).

Beds are a crucial source of house dust mite (HDM) allergens, which play a major role in allergic disease, particularly asthma. HDM require a specific combination of hygrothermal conditions to thrive. These bed conditions depend on a number of interacting factors, such as: external climate; building characteristics; heating, ventilation and moisture-producing habits; mattress properties; etc. Because of the complexity of the many interacting factors occuring in real dwellings, a modelling approach is required, whereby the models' predictions have to be consistent with field results. This thesis tested the hypothesis that a combined HDM population-hygrothermal model for beds can adequately predict field data and that the model can be a valuable tool for scenario modelling and intervention studies focused on the psychrometric control of house dust mites in UK housing. Two combined models were considered: a simple steady-state one-dimensional model (BED/MPI), and a complex transient three-dimensional mode (Lectus/Popmite). A combination of fieldwork and scenarios modelling was carried out, which involved hygrothermal and mite monitoring of 25 beds, utilising a novel technique whereby live mites were caged in mite bags and installed in monitored beds and bedrooms (82 sets of mites bags). The work was carried out as part of a multidisciplinary project aimed at developing and testing the models. Good agreement was found between field data and the models predictions, particularly when the uncertainties due to input variables and measurements were taken into account. The results showed that under borderline conditions for HDM growth, simple steady-state predictions may not be accurate. Temperature, not only RH, is a critical variable for HDMs. Areas for model improvement were also identified. In particular, factors other than hygrothermal conditions may be crucial for a beds mite carrying capacity, requiring further investigation: food, space availability, and mite movement. Despite these uncertainties, it can be concluded that greater ventilation, increased thermostat settings and reduced moisture rates can decrease mite levels in beds. The ventilation rates provided by some mechanical ventilation with heat recovery systems may be inadequate to sufficiently control moisture and reduce mite growth. Scenarios modelling suggests that there is considerable potential for the psychrometric control of house dust mites in UK dwellings.

[Truncated abstract] The last few decades have witnessed an increase in the prevalence, morbidity and economic burden associated with asthma and allergic disease. This rising incidence cannot be completely explained by changes in genetic factors or by improvements in diagnostic procedures. Environmental factors, particularly those associated with a westernised lifestyle, are considered to be involved in this increase. In the late 1980’s Strachan was the first to link environmental factors with allergic disease, this theory became to be known as the ‘hygiene hypothesis’. This hypothesis links the “cleaner” more “healthy ” environment we now live in, with an increased risk of developing allergic disease. This effect is highlighted by studies linking farm and animal exposure (rich in microbial compounds) during early life with a decrease in allergic disease. Since then numerous studies have been undertaken to ascertain the factors present in the microbe rich environment, which elicit this protective effect. Many studies have revolved around endotoxin, however microbial components (mainly from Gram-positive bacteria) which signal through Toll-like receptor 2 (TLR2), have also shown that they can alter the allergic immune response. In mice models TLR2 has been shown to both exacerbate and inhibit allergic disease. The above research highlights the need for further studies into the effect of TLR2 ligands, and to define the mechanisms by which they exert their effects in human allergic disease. These mechanisms will be relevant to understanding the pathogenesis of allergy, but also might provide novel ways to treat allergy. The aims of the study outlined in this thesis were to determine whether in vitro exposure to TLR2 ligands could modify the established immune response to house dust mite allergen (HDM), and to examine the mechanisms by which this occurs. ... The addition of glucocorticoids to LTA enhanced the ability of this TLR2 ligand to inhibit IL-5 and IL-13 production by HDM-activated blood mononuclear cells. In conclusion, this study shows that TLR2 ligands have the ability to inhibit the Th2 response to mite allergen in previously sensitized individuals by an as yet unknown mechanism. However the findings described herein do provide an impetus for future studies designed to uncover novel mechanisms by which allergic responses can be ameliorated, and may open new treatment modalities.

Canine atopic dermatitis (CAD) is a common dermatosis, defined as a genetic-based disease, which predisposes to cutaneous inflammation and pruritus, mediated by class IgE immunoglobulins directed against specific antigens in most cases. Clinical diagnosis may be later complemented by skin allergic and/or serological tests (ELISA). The aim of these tests is to identify possible allergens in order to enable the clinicians to select candidate antigens for allergen specific immunotherapy. This work aimed to identify the sensitization profile of 58 dogs with atopic dermatitis diagnosis. All animals were submitted to intradermic test (IDT) and screened for the presence of antibodies against different allergens using a serologic test. House dust mites are described as the most frequent allergens in all continents. However, the positivity to C. dactylon is not commonly described and may be characteristic for the region. With this work it was possible to identify the main allergens involved in the immunologic response of atopic dogs residing in Rio Grande do Sul, pointing to the importance to include C. dactylon in screening tests for allergy.
A dermatite atópica canina (DAC) é uma dermatose comum, definida como uma doença de cunho genético que predispõe à inflamação e ao prurido cutâneo, mediada por imunoglobulinas da classe IgE dirigidas contra antígenos específicos na maior parte dos casos. O diagnóstico da DAC é clínico e pode ser posteriormente complementado por testes alérgicos cutâneos e/ou sorológicos. O objetivo desses testes é identificar possíveis alérgenos e, com isso, possibilitar ao clínico a seleção de antígenos candidatos para a imunoterapia alérgeno-específica. No presente trabalho buscou-se identificar o perfil de sensibilização de 58 cães diagnosticados com dermatite atópica. Todos os animais foram submetidos ao teste intradérmico (TID) e à detecção de anticorpos específicos para diferentes alérgenos através de teste sorológico (ELISA). Os ácaros domiciliares são descritos como os alérgenos mais frequentes em todos os continentes. Entretanto, a positividade ao C. dactylon não é usualmente descrita e pode ser característica da região. Com esse trabalho foi possível identificar os principais alérgenos envolvidos na resposta imunológica de cães atópicos residentes no Rio Grande do Sul, ressaltando-se a importância da inclusão do extrato de C. dactylon em testes alérgicos.

The overall aims of our studies were to identify risk factors for respiratory symptoms and asthma in indoor environment but even to look at some personal risk factors such as body mass index and gastroesophageal reflux. The study population is based on participants of the European Community Respiratory Health Survey I and II.

In the first study, water damage and visible moulds were reported in 7.4% and 17% of the homes respectively. The combination of water damage and visible moulds was independently associated with attacks of breathlessness when resting and after activity and also to long term cough. In the second study, the prevalence of nocturnal GER increased with higher BMI and the same pattern could be seen for habitual snoring. Reported onset of asthma, wheeze and night-time symptoms increased in prevalence along with the BMI gradient. In the multivariable analysis, obesity and nocturnal GER were independent risk factors for onset of asthma, wheeze and night-time symptoms. Habitual snoring was an independent risk factor for onset of wheeze and night-time symptoms, but not for onset of asthma. In the third study, a total of 18% of the subjects reported indoor dampness in the last 12 months and 27% of the subjects reported indoor dampness since the previous survey. Respiratory symptoms and asthma were significantly more prevalent in individuals exposed to indoor dampness and indoor dampness was a risk factor for respiratory symptoms and asthma after adjusting for possible confounders. Indoor dampness was an independent risk factor for onset of respiratory symptoms but not for asthma onset. Remission of respiratory symptoms was less likely to occur if subjects reported indoor dampness. In the fourth study, the lowest prevalence of atopy and the lowest levels of all indoor allergens, bacteria and moulds were found in Iceland. A positive association was found, between cat allergen exposure and asthma symptoms and between bronchial hyperresponsiveness and the amount of viable mould in indoor air.

Notre volonté d'économiser l'énergie nous pousse à vivre dans un environnement confiné favorisant les acariens et les micro-organismes. L'objectif de la thèse est de caractériser la contamination en acariens et en micro-organismes des logements de patients présentant des pathologies respiratoires, d'évaluer l'influence des interactions acariens/moisissures sur l'exposition aux allergènes et de comprendre les facteurs favorisant la pollution biologique de l'air intérieur. Afin de disposer d'un outil commun aux acariens et aux micro-organismes, un modèle innovant de quantification des acariens pas qPCR a été mis au point. Les acariens de stockage sont sous-estimés et les mesures d'éviction doivent être appliquées à l'ensemble de l'habitat. L'observation des interactions acariens/moisissures a montré une vraie relation symbiotique: dispersion des moisissures et apports des nutriments essentiels aux acariens. La contamination des logements de producteurs laitiers atteint de BPCO a été comparée à celle de producteurs laitiers sains, de patients BPCO non­-agriculteurs et de sujets sains non-agriculteurs. L'exposition agricole est abondante et spécifique à certains micro­organismes caractéristiques de la ferme et la sensibilité IgG à Wallemia sebi est spécifique des producteurs laitiers BPCO Le suivi de l'impact du compostage sur la qualité biologique de l'air intérieur a démontré une augmentation des concentrations en acariens de stockage et certaines moisissures circonscrite au bio-seau. De nouveaux indicateurs communs aux acariens, aux moisissures et aux bactéries devraient nous permettre de progresser dans la détermination de la relation dose/effet
Our will to save energy leads us to live in a confined environment providing the ideal conditions to mites and microorganisms development. The aim of the thesis is to characterize mites and microorganisms contamination of dwellings from patients suffering respiratory diseases, to estimate the influence of the interactions between various organic communities on the allergens exposure and to understand the factors increasing the biological pollution ofindoor air. To evaluate our exposition, we needed to quantify mites and microorganisms with a common tool and an innovative quantification mode! of domestic mites by qPCR was developed. The presence of storage mites is overemphasized in dwellings of allergie patients and the eviction measures of mites should be applied into any rooms of dwellings. The contamination of dairy fanners' dwellings suffering from COPD was compared with that ofhealthy dairy fanners, COPC patients non-farmers and healthy non-fanners. In dwellings, the dairy fanners' exposure was important and specific ofth1 fanning environment. The lgG sensitivity to Wallemia sebi was significantly specific of dairy fanners suffering from COPD. The impact of the composting on the biological air quality was evaluated and the concentrations in storage mites and some molds increased significantly only in a confined area around the waste bin. New common indicators of domestic mites, molds and bacteria should allow us to progress in the determination of the dose-response relationship for the different allergens and their possible synergie effects

Les effets anti-allergiques des bactéries lactiques sont suggérés par plusieurs études épidémiologiques, des essais cliniques et des modèles expérimentaux d’allergie. Cependant, les propriétés immunomodulatrices des bactéries lactiques sont sous-exploitées par les stratégies vaccinales développées pour combattre l’allergie et les mécanismes empruntés par ces bactéries pour moduler l’allergie restent peu caractérisés.

Dès lors, nous avons caractérisé les propriétés immunomodulatrices qu’exerce Lactobacillus plantarum NCIMB8826, une bactérie lactique modèle, sur la cellule dendritique étant donné le rôle déterminant de cette cellule sur la réponse allergique. Nous montrons que L. plantarum induit une forte sécrétion d’IL-12 p40, d’IL-12 p70, de TNF-a mais une faible production d’IL-10. Cette faculté à induire la sécrétion de cytokines polarisantes dépend de TLR2, de TLR9, de MyD88, de NF-kB, des MAPKs (en particulier JNK, p38 et ERK 1/2), de la composition de l’acide lipotéichoïque de L. plantarum et de CD14. Nous montrons aussi que l’ADN génomique de L. plantarum est un agoniste de TLR9 et que CD14 et CD36 facilitent la liaison de la cellule dendritique avec L. plantarum.

Ensuite, nous avons évalué le potentiel vaccinal d’une coadministration L. plantarum + Der p 1 dans un modèle murin d’allergie à Der p 1. Cette formulation vaccinale prévient la production d’IgE Der p 1-spécifique et atténue l’éosinophilie pulmonaire tout en stimulant une forte production d’anticorps IgG2a Der p 1-spécifiques et d’IFN-g par les cellules spléniques. Ces effets bénéfiques nous ont conduit à élaborer une bactérie lactique recombinante dérivée de L. plantarum produisant Der p 1 pour la vaccination contre l’allergie aux acariens. La forme antigénique que nous avons réussi à faire produire par L. plantarum correspond à une protéine de fusion entre la Maltose Binding Protein de E. coli et ProDer p 1 (le zymogène de Der p 1), la présence de ce partenaire de fusion étant indispensable à la production de ProDer p 1. En prophylaxie, la vaccination par cette bactérie recombinante prévient la production d’anticorps IgE-Der p 1-spécifiques et stimule la production d’anticorps IgG2a spécifiques, reproduisant les effets de la coadministration L. plantarum + Der p 1. Elle réduit de manière drastique la production d’IL-5 des cellules spléniques et des cellules ganglionnaires médiastinales et prévient l’éosinophilie pulmonaire mais n’a pas d’effet sur l’hyperréactivité bronchique. Der p 1 étant un des allergènes d’acarien les plus immunodominants, cet ensemble de données montre donc que cette bactérie recombinante constitue un vaccin prophylactique prometteur pour la prévention de l’allergie aux acariens. Des résultats préliminaires obtenus à partir de cellules dendritiques humaines et lymphocytes T autologues montrent la forte capacité de cette bactérie recombinante à induire le développement d’une réponse Th1 fortement polarisée (production d’IFN-g en l’absence de production d’IL-4 et d’IL-5), ce qui suggère que l’utilisation de cette bactérie recombinante pourrait être envisagée pour le traitement de l’allergie chez l’homme.

Doctorat en Sciences agronomiques et ingénierie biologique
info:eu-repo/semantics/nonPublished

Indoor air quality is described as the chemical, physical and biological characteristics of air in a residential or occupational indoor environment. In residential settings, there are many contributions to indoor pollution levels namely; human activities, biological sources and outdoor air. There has been increased focus on house dust due to its potential to contain biological and chemical pollutants in indoor environments. These have the potential to cause harm to human health. The purpose of this study was to conduct toxicological analysis of house dust collected from inside selected Durban residential buildings. The objectives of this study were to isolate, identify and quantify mould occurrence in house dust samples; to measure the occurrence of heavy metals (arsenic, lead and mercury) in house dust; and to analyse the cytotoxicity of house dust on human lung bronchus carcinoma epithelial line (A549) and human lung bronchus virus transformed epithelial cell line (BBM). One hundred and five house dust samples were obtained from households that participated in the South Durban Health Study. In each home, a sample of settled dust was collected, using standardized protocols, then sieved and individually packed into polystyrene bags. The samples were taken from three surface areas namely; living room couches, bed mattresses, and carpets. Well documented methods were used for the isolation, identification and quantification of mould. The samples for heavy metals analysis were sent to Umgeni Water (chemistry laboratory, Pietermaritzburg) where standardised methods were used. Human cell lines were treated with five different dilutions of each house dust extract. Cell viability was assessed using the MTT assay. Toxic effects of house dust extract were analyzed, following house dust extract treatment and cells were stained with double dye (annexin-V- and propidium iodide) and analysed with flow cytometry, and fluorescent microscope. Cytokines were analysed by Microbionix (Neuried, German) using a Luminex®100 plate reader for multiplex human cytokines analysis. There were (n=128) mould types isolated and (n=105) were identified, of which (n=10) were predominately isolated moulds. This was further confirmed by Allerton Provincial Laboratory in Pietermaritzburg. Among the isolated genera in all three surface areas, Rhizopus spp and Penicillium spp were widely distributed throughout surface areas in greater proportion. The overall highest mean which was reported in this study and expressed in colony forming unit per gram (CFU/g) for Penicillium spp ranged (3400 - 62316 CFU/g) obtained from living room couches, followed by Rhizopus spp (5200 - 15990 CFU/g). The mould results were compared with the South African Occupational Health and Safety Act (OHSA) 85 of 1993 as amended suggested guidelines of 1,000, 000 CFU/g. The findings of this study suggest the moulds in the homes studied were below the suggested guideline. However, this does not imply that the indoor conditions are unsafe or hazardous. Instead, the findings act as an indicator of moulds presence indoors. The type of airborne mould, its concentration and extent of exposure and the health status of the occupants of a building will determine the health effects on an individual. Heavy metals were detected in the dust in the following ascending order: arsenic (As) ranged from 1.3 ug/g -18.4 ug/g (mean, 4.26 ug/g), lead (Pb) ranged from 28.0 - 872 ug/g (mean 171.66 ug/g), and mercury (Hg) ranged from 0.6 -19.0 ug/g (mean, 2.22 ug/g). The mean concentration of lead in the dust was within the range of Canadian National Classification guidelines on residential contamination (500 ug/g). There was numerous numbers of samples in this study that exceeded these guidelines. The mean concentration of arsenic was within residential soil guidelines (20 ug/g). Mercury was within limits when compared with Global Hg project guidelines of soil/residential (6.6 ug/g), thought some of samples were notably above this mean. The ability of house dust extract to lower the cell viability which was slightly above 80% (prior treatment) to less than 50% (post treatment) in both cells was observed in this study. The findings in this study showed that dust extract are toxic to human cell lines, and cells undergone a degree of apoptosis and necrosis 62% (A549) and 99% (BBM). The cytokines serve an important role in the non-specific defence external against insults. It was observed that A549 cells up-regulated the release of IL-6 and IL-8 pro-inflammatory cytokines and under-regulated the release of other cytokines analysed (IL-4, IL-13, and TNF-a). BBM cells released IL-4, IL-8 and IL-13 within limit of detection. The presence of moulds in these sampled indoor household dusts, which is comparable with findings elsewhere indoors, show that moulds act as an indicator for building conditions such as dampness, which supports mould growth. Individuals, whether they are sensitized or not, may develop allergic reactions towards spores, thus the elevated numbers of spores quantified in this study are of concern. Some of the heavy metals reported in this study were higher or marginally higher than international norms and guidelines. The findings in this study strongly suggest that house dust extract is toxic to human lung cell lines. It must be noted, however, that this study may not reflect all that happens when a human lung is exposed to house dust. The findings of this study could contribute to the development of South African indoor air guidelines. In conclusion further study needed to be undertaken with respect to air pollution disease such as allergic; the reason being this study shown the reduced expression of cytokines that are involved in allergic inflammation.
Thesis (M.Med.)-University of KwaZulu-Natal, Durban, 2009.

碩士
國立陽明大學
寄生蟲學研究所
89
From November, 1999 through October, 2000, house dust mites were surveyed in three urban areas of Taiwan, Taipei, Taoyaun and Taichung. Thirty-three households of healthy inhabitants and seventeen households with patients suffering from allergic hypersensitivity were included in this study. Data indicated that the density of house mites positively correlated with room temperature and relative humidity. Dermatophagoides pternyssinus and D. farinae appeared to be the most dominant species among seven species of mites. These mites appeared mostly in collections from pillow, bed covering and mattress within the bedroom. Statistical analyses was made to test the significance among mite densities for different parameters, which included nature of materials of household items, frequency of onset of air condition and dehumidifier, and the weekly clean effect. Data revealed that woolen carpet and bed covering carried more mites than other materials. They also suggested that increasing use of air condition and dehumidifier, and increasing of cleaning activity significantly lowered population. Polymerase chain reaction was used to amplify the DNA fragment containing ITS-1, 5.8S and ITS-2 for four species of mites that usually collected from house dust. These mites included colonies of D. farinae, D. pteronyssinus, two collected colonies of Tyrophagus putrescentiae and Chelytus eruditis. These fragments were cloned and sequenced. Sequence data indicate that ITS-1 appears to be longer than that of ITS-2 in these four mites. Because the length of the ITS-1 and ITS-2 differed among with species, it could be regarded as a molecular marker for species identification. Homology of nucleotide sequence homology was higher revealed between closely related species of D. farinae and D. pteronyssinus and lower among distantly related ones. Moreover, one EcoR1 cutting site exists in the sequence of D. farinae but not in D. pteronyssinus. A ratio of 1% variation was found within the sequences of two colonies of T. putrescentiae.

Understanding the transport of particulate and gaseous indoor air pollutants from source to exposure is paramount to improve our understanding of the complexities of the built environments in which we spend the majority of our time. This dissertation offers new insights on particle resuspension from indoor surfaces, infant exposure to organic contaminants released from crib mattresses, and the dynamics of pollutant transport and human exposure while sleeping. Particle resuspension is the physical process by which settled particles detach from a surface and become airborne through application of various aerodynamic and mechanical removal forces. Resuspension is an important indoor source of coarse mode particles (> 1 µm in diameter) and can be a source mechanism for biological matter and organic contaminants that accumulate in house dust. Settled dust deposits on indoor surfaces can vary considerably in their structure and mass loading, yet little is known as to how these parameters affect resuspension. Through wind tunnel experiments, this research demonstrates that the deposit structure (monolayer or multilayer) can have a significant impact on the number of particles that aerodynamically resuspend. Furthermore, this dissertation presents the first full-scale experimental chamber study to show that human body movements in bed can resuspend settled mattress dust particles. An indoor aerosol model was utilized to provide a mechanistic understanding of the impact of movement intensity, surface vibrations, bedroom ventilation rate, and dust loading on the resuspension flux and intake fraction of resuspended particles. Infants spend most of their time sleeping and are likely to be exposed to elevated concentrations of chemicals released from their crib mattresses. Through a combination of chamber experiments and solvent extractions, this research shows that infant crib mattresses can emit a variety of volatile organic compounds (VOCs) and contain numerous chemical additives, including phthalate and alternative plasticizers, flame retardants, and unreacted isocyanates. Additionally, this study discovered that infants are exposed to approximately twice the concentrations of VOCs in their breathing zones as compared to the bulk bedroom air, due to their close proximity to the source.