Mite Allergen Levels Research Articles

Measurement of Dermatophagoides mite allergens on bedding and human skin surfaces.

The level of the Dermatophagoides mite group 1 (Der 1) allergens in reservoir dust has been used as an index of exposure in most studies. However, the mite allergen level in reservoir dust cannot directly reflect the personal exposure level. We sought to develop a new method for quantifying the Der 1 allergens on bedding and human skin surfaces as an index of exposure to mite allergens. Samples were obtained with a small adhesive tape from the forearm skin of 30 healthy volunteers and from their regularly used mattresses. The level of Der 1 allergens collected onto the adhesive tape was measured by a newly developed sensitive fluorometric ELISA for Der p 1 and Der f 1. The Der 1 allergens could be detected in all the samples from bedding surfaces and in 28 of the 30 samples from skin surfaces. The Der 1 levels by adhesive tape sampling from the mattresses correlated with those by reservoir dust sampling. The sampling of the skin and bedding surface with adhesive tape correlated, but skin sampling did not correlate with reservoir sampling. The Der 1 allergens on bedding surfaces and on human skin surfaces could be quantified with a very simple sampling technique. The system developed in this study will provide a new tool for the assessment of mite allergen exposure in daily life.

Environmental exposure reduction in high-risk newborns: where do we start?

When analyzing the effect of environmental exposure reduction measures on asthma in high-risk children, one must know how far asthmatic families already have applied such measures, because this would affect the effectiveness and efficiency of interventions aimed at reducing environmental exposure. To describe the room for improvement by asthmatic families in mite, pet, and food allergen reducing measures and in parental passive smoking and to determine the resulting levels of mite and pet allergens by the applied sanitation measures. Data were sampled by observation, weekly diary entries, and questionnaire when the infant was 6 months old and 1 year old. Dust samples were collected by vacuuming the living room floor and the parental and infant mattresses. Multiple logistic regression analyses were applied with the use of mattress encasing, having a smooth floor covering, having pets, exclusive breast-feeding and/or hypoallergenic formula during the infant's first 6 months, and passive smoking as the dependent variables. Frequencies of applied measures were as follows: having a smooth floor covering, 36%; daily house cleaning, 27%; use of parental and infant antimite mattress encasings, 13% and 9%, respectively; keeping no pets, 66%; no cow's milk-based regular formula, 13%; no solid foods in the first 6 months of life, 28%; and abstinence of smoking by the mother prenatally, 89%; by the mother postnatally, 85%; and by her partner, 76%. Having a smooth floor covering and daily cleaning but not use of antimite mattress encasings resulted in significantly lower mite and pet allergen levels. There is (still) enough room for improvement to reduce exposure to inhalant and food allergens, especially by application of mattress encasings, exclusive breast-feeding and/or hypoallergenic formula feeding, and postponing the time until first solids are given.

EARLY INDOOR MICROBIAL EXPOSURE LOWERS THE RISK OF ASTHMA

Early life exposures to microbial agents such as bacterial endotoxin have been suggested to inhibit the development of atopy and asthma. In this study we assessed the relation between living room floor levels of bacterial endotoxin, fungal β(1,3)-glucan and fungal extracellular polysaccharides (EPS-Pen/Asp) and the development of atopic sensitisation and asthma in 810 infants born from allergic parents. Exposure to microbial agents was determined at 3 months, serum IgE at 12 and 24 months, and asthma symptoms & diagnosis at 12, 24, and 48 months. Low, medium and high exposure groups were defined based on tertiles of the exposure distributions. Analyses were adjusted for gender, pets, ETS, siblings, parental education, and mite allergen levels. Microbial exposure was inversely associated with atopic sensitization at 24 months in a dose dependent manner with ORs ranging from 0.3–0.5 for the highest exposure groups (statistically significant only for EPS-Pen/Asp). A similar but weaker dose response was observed for atopy at 12 months. A doctor's diagnosis of asthma at 48 months was also less common in highly exposed children with ORs ranging from 0.3–0.5, statistically significant (p < 0.01) for endotoxin and EPS. A protective effect in the medium exposure group was also observed but the effect was less pronounced suggesting a dose-response effect. These protective effects on doctor's diagnosed asthma were shown consistently across the three time points, but were statistically significant only at 24 and 48 months. Interestingly, the protective effects of microbial exposure were observed both in atopic and non-atopic asthmatics. Asthma symptoms (wheeze and night cough) in the last 12 months (at age 4) were slightly less prevalent in the high exposure groups (NS). No associations were found for eczema. Endotoxin, EPS-Pen/Asp, and glucan concentrations were highly correlated limiting the potential to study them separately. In conclusion, although our findings need confirmation at older ages, they provide, for the first time, evidence from a prospective cohort study that non-infectious microbial exposure at a very young age may protect from developing atopy and asthma.

Distribution of house dust mite allergen: comparing house dust mite allergen levels in dust samples collected from different sites on living room floors with smooth coverings.

The distribution of house dust mite allergen (Der p1) in living rooms with smooth floor coverings, as measured in the middle compared with the border of the floor was investigated. It was hypothesized that activity causes displacement of Der p1, from the middle towards the border. Dust samples from the middle and border of 50 floors with smooth coverings were collected and analysed on Der p1 content in a standardized way. The Der p1 exposure expressed as per unit area (ng/m2) showed that border samples contained significantly more Der p1 compared with middle samples (median: 2.57 vs 0.27, respectively, P = 0.023). Presence of pets and presence of more than two inhabitants increased the difference. When expressed as per unit weight of dust (ng/g), significant differences were only detected when comparing Der p1 content of samples collected in households with three or more inhabitants [median: 2 (border) vs 53 (middle), respectively; P = 0.035]. The Der p1 is unequally distributed on living room floors with smooth coverings, most likely because of displacement of dust from the middle towards the border due to activity. Expression as ng/g of dust and ng/m2 could not obviously be interchangeable.

An association between plastic mattress covers and sheepskin underbedding use in infancy and house dust mite sensitization in childhood: a prospective study.

Higher house dust mite (HDM) allergen exposure during infancy has been associated with increased HDM sensitization. Infant bedding has been associated with the accumulation of varying levels of HDM. Prospective data on the relationship between infant bedding and the development of HDM sensitization has not been previously examined. To determine if particular types of bedding used in infancy are associated with increased risk of house dust mite sensitization in childhood. A population-based sample (n = 498) of children born in 1988 or 1989, and who were resident in Northern Tasmania in 1997, participated in this study. These children were part of a birth cohort study (1988-95), the Tasmanian Infant Health Survey. Data on infant underbedding and mattresses was available on 460 and 457 children, respectively. The main outcome measure was HDM sensitization defined as a skin prick test (SPT) reaction of 3 mm or more to the allergens of Dermatophagoides pteronyssinus and/or Dermatophagoides farinae. The use of either sheepskin underbedding or plastic mattress covers in infancy was associated with an increased risk of sensitization to HDM allergens at age 8 years. The adjusted risk ratio (RR) for sensitization to HDM with sheepskin in infancy was 2.27 (95% CI: 1.14, 4.55), P = 0.020. The adjusted RR for sensitization to HDM with the use of plastic mattress covers in infancy was 2.06 (95% CI: 1.22, 3.51), P = 0.007. The use of a foam mattress in infancy was not related to subsequent HDM sensitization. Infant's bedding plays a role in the development of HDM sensitization in childhood. Intervention studies to examine mite allergen levels and the role of underbedding on the development of HDM sensitization are required.

The effect of storage on allergen and microbial agent levels in frozen house dust

House dust samples collected for exposure studies are often stored for variable time periods until analysis. However, there is currently no information on the effects of dust storage on the content of biocontaminants. Therefore, associations were analysed between the levels of mite allergens (Der p 1, Der f 1), cat allergen (Fel d 1) and microbial components (endotoxin, beta(1-->3)-glucan) on the one hand and the storage duration of dust samples at -20 degrees C on the other hand. Within the framework of a study on the influences of INdoor factors and Genetics on Asthma (INGA), dust samples were collected from living room floors between June 1995 and August 1998 and extracted according to a standardized protocol. The concentrations of Der p 1, Der f 1, Fel d 1 and beta(1-->3)-glucan were determined with specific enzyme immunoassays. Endotoxin content was quantified using a chromogenic kinetic Limulus amoebocyte lysate (LAL) test. All concentrations were expressed per gram of dust Dust samples (n = 1236) were obtained from 655 homes in Hamburg, Hettstedt, Zerbst and Bitterfeld. Storage duration (range 8-298 days) was grouped into four categories (<or= 60 d; 61-90 d; 91-120 d; > 120 d). After adjustment for city of residence and season of dust sampling, means ratios comparing categories 2-4 to the first category were not statistically significant for Der p 1, Der f 1, endotoxin and beta(1-->3 glucan). However, Fel d 1 concentrations significantly declined with increased storage times of dust samples. Storage of house dust at -20 degrees C for up to 10 months has no effect on mite allergen, endotoxin and beta(1-->3)-glucan levels. A potential loss of Fel d 1 during storage of frozen dust samples needs further investigations by repeated measurements of allergen in identical dust samples.

House dust mite allergen in US beds: Results from the first national survey of lead and allergens in housing

Background: Although exposure to house dust mite allergen is a major risk factor for allergic sensitization and asthma, nationwide estimates of dust mite allergen levels in US homes have not been reported. Objective: The purpose of this study was to estimate the prevalence of dust mite allergen in beds of US homes and to identify predictors of dust mite allergen concentration. Methods: Data were obtained from the first National Survey of Lead and Allergens in Housing, a cross-sectional survey of 831 permanently occupied noninstitutional housing units that permitted resident children. Dust mite allergen concentration (Der f 1 plus Der p 1) was determined from a dust sample collected from a bed. The percentages of homes with concentrations at or greater than detection, 2.0 μg/g bed dust, and 10.0 μg/g bed dust were estimated. Independent predictors of allergen concentration were assessed with multivariable linear regression. Results: The percentages of US homes with dust mite allergen concentrations at or greater than detection, 2.0 μg/g, and 10.0 μg/g were 84.2% (SE, 1.73), 46.2% (SE, 2.0), and 24.2% (SE, 2.1), respectively. Independent predictors of higher levels were older homes, non-West census regions, single-family homes, no resident children, lower household income, heating sources other than forced air, musty or mildew odor, and higher bedroom humidity. Conclusion: Most US homes have detectable levels of dust mite allergen in a bed. Levels previously associated with allergic sensitization and asthma are common in US bedrooms. Predictors can be used to identify conditions under which homes are more likely to have increased dust mite allergen levels. (J Allergy Clin Immunol 2003;111:408-14.)

The long-term effect of environmental control measures on mite, cat, and dog allergen levels

The long-term effect of environmental control measures on mite, cat, and dog allergen levels

House dust mite allergen levels in carpeted sleeping accommodation are higher in private houses than public places.

To compare mite allergen levels in carpeted sleeping accommodation in private dwellings and public places. The concentration of Dermatophagoides pteronyssinus Group 1 allergen in house dust was measured in mat-tresses and bedroom floors in 12 homes, 5 hotels, 11 child care centres and a university hall of residence. Indoor temperature and relative humidity were also measured. A questionnaire clarified details regarding the age of the building, age of the carpet, method and frequency of cleaning, frequency of room use and use of air-conditioning. Median allergen levels in mattresses and carpets in private homes (21.1 and 20.6 micro g/g dust, respectively) were significantly higher than in public places (2.5 and 3.1 micro g/g, respectively; P < 0.0001). Mean relative humidity was significantly higher in private houses (68.5%; 95% CI 67.2-69.3%) than in public places (56.4%; 95% CI 52.7-60.1%; P < 0.0001). Carpeted sleeping accommodation in public places has lower house dust mite allergen levels than private houses. Lower levels of relative humidity may be an important component of the explanation.

Association between Mite Allergen (Der p 1, Der f 1, Blo t 5) Levels and Microscopic Identification of Mites or Skin Prick Test Results in Asthmatic Subjects

Background: Mite allergens have been involved in airway sensitization and allergic diseases. Immunoassays for the identification and quantifiction of house dust mite (HDM) allergens are useful to improve the knowledge of regional mite fauna and the remediation of mite allergens in allergic diseases. The present study analyzed the association between levels of HDM allergen and results of mite identification or skin prick test (SPT) in two different areas of Bahia, Brazil. Methods: Forty-two asthmatic subjects from a rural area (group I; n = 21) and a slum (group II; n = 21) were evaluated through SPT with HDM allergens and had dust samples collected at their homes for mite identification and allergen measurements. Results: Positive SPT to Dermatophagoides pteronyssinus, Dermatophagoides farinae and Blomia tropicalis allergens were observed in 42.9, 38.0 and 42.9% subjects from group I and in 47.6, 19.0 and 33.3% subjects from group II, respectively. D. pteronyssinus and B. tropicalis were identified in approximately 76 and 50% of samples from both groups, respectively. D. farinae was identified in 38.0 and 9.5% of samples from groups I and II, respectively (p < 0.005). Der p 1, Der f 1 and Blo t 5 detection were associated with mite identification (p < 0.05). Association between HDM allergen levels over 2 µg/g of dust and positive SPT occurred only with D. pteronyssinus (p < 0.0001). Conclusions:D. pteronyssinus was the most prevalent mite species in this study followed by B. tropicalis and D. farinae. Immunoassays done to measure mite allergens were associated with mite-species identification. We conclude that these three mite species must be included on panels for the diagnosis of allergic airway diseases in subjects living in such regions.

Mite and pet allergen levels in homes of children born to allergic and nonallergic parents: the PIAMA study.

The Prevention and Incidence of Asthma and Mite Allergy (PIAMA) study is a birth cohort study that investigates the influence of allergen exposure on the development of allergy and asthma in the first several years of life. The objectives of this study were to investigate the relationship between a family history of allergy and/or asthma and exposure of newborn children to mite and pet allergen and to study the influence of different home and occupant characteristics on mite allergen exposure. Dust was sampled from the child's mattress and the parental mattress at 3 months after birth of the index child and analyzed for mite and pet allergens. Subjects were divided in groups according to history of asthma and allergy in their parents, and allergen exposure was studied in the different groups. Cat allergen exposure was significantly lower on parental mattresses in families with allergic mothers, but dog allergen exposure was not different. Mite allergen exposure was lower on parental mattresses in families with allergic mothers. Use of mite allergen-impermeable mattress covers reduced mite allergen exposure. Some other characteristics such as age of home and mattress were also found to influence mite allergen exposure. Parental mattresses in homes of allergic mothers had lower cat and mite (but not dog) allergen loadings than mattresses in homes of nonallergic parents. Paternal (as opposed to maternal) allergy seemed to have little influence.

Household characteristics and mite allergen levels in Manchester,UK.

Mite allergen levels vary enormously between different homes in the same geographical area. No large scale studies of mite levels in Manchester homes has been conducted to identify factors associated with higher levels. To quantify exposure to mite allergens and to identify characteristics associated with higher Der p 1 levels in a large sample of homes in Manchester, UK. Der p 1 was measured in dust from the living room floor, sofa, bedroom floor and mattress in 564 homes. Data on household characteristics were collected by administering a questionnaire. Univariate and multivariate analyses were performed to identify household characteristics associated with higher mite allergen levels. Der p 1 levels were highest in the mattress (GM 1.19 microg/g, 95% CI 0.98-1.45, P < 0.001). Two-thirds of homes contained Der p 1 levels > 2 microg/g in at least one dust reservoir, and 40.3% contained Der p 1 greater than 10 microg/g. There was a large range in Der p 1 levels between homes (> 10(3)-fold). Damp and condensation were common findings in homes. In the multivariate analyses, factors associated with higher Der p 1 levels in more than one dust reservoir were older homes, older living room carpets, damp, condensation and mixed glazing. Older mattresses were associated with higher mite allergen levels in the mattress where the age of the mattress was recorded. Twenty-four homes contained no detectable mite allergen, six of which reported damp. Mite allergen levels are high enough in two of every three homes to be associated with an increase in the risk of sensitization to mite. Factors such as older homes, carpets and mattresses, damp and condensation are associated with higher mite allergen. However, mite allergen levels are occasionally unpredictably very low in homes with risk factors for high levels.

Daycare centers and schools as sources of exposure to mites, cockroach, and endotoxin in the city of São Paulo, Brazil.

Public places, including schools, have been identified as sources of exposure to allergens derived from mites, cockroach, cat, and dog and to endotoxin. The purposes of this study were to assess and compare exposure to allergens and endotoxin in 4 types of public child-care facilities in Brazil and to investigate whether the presence of children and the performance of cleaning procedures could have an influence on allergen and endotoxin levels. We have analyzed dust from bedding, floors, chairs, and tables of daycare centers (DCs), preschools, kindergartens, and elementary schools (ESs). Major allergens from mites, cockroach, cat, and dog were quantitated by means of ELISA, and endotoxin content was determined by using the Limulus Amebocyte Lysate assay. Group 1 mite allergens were greater than 2 microg/g in 67% of DC and preschool samples and in 8.9% and 2.2% of kindergarten and ES samples, respectively. The presence of bedding in DCs and preschools accounted for increased levels of mite allergens in these settings. Levels of Bla g 1 were higher in ES floors compared with those found in DC and preschool floors. Low levels (<1 microg/g) of Fel d 1 e Can f 1 were found in most samples. Levels of endotoxin in DCs and preschools were 3 times higher than in ESs. DCs and schools in Brazil should be considered as important sources of exposure to dust mites and cockroach allergens and to endotoxin. Recommendations for mite allergen avoidance should include appropriate care of bedding in DCs and preschools.

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Clinical evaluation of the effect of anti-allergic mattress covers in patients with moderate to severe asthma and house dust mite allergy: a randomised double blind placebo controlled study

Background: The use of anti-allergic mattress covers in patients with asthma can result in a large reduction in the level of house dust mite allergen in dust samples. Apart from...

Allergens and endotoxin on mothers' mattresses and total immunoglobulin E in cord blood of neonates.

The current authors examined whether mite and cat allergen and bacterial endotoxin levels in dust of the mothers' mattresses were associated with cord blood immunoglobulin (Ig)E (CB-IgE) levels in newborns. Data from 1,332 term and normal weight neonates, from an ongoing birth cohort study, influences of life-style related factors on the immune system and the development of allergies in childhood (LISA), with complete information on exposure to biocontaminants in mattress dust and CB-IgE were analysed. Two thirds of CB-IgE were undetectable (<0.35 kU x L(-1)). Thus, 0.35 and 0.45 kU x L(-1) (4th quartile) were chosen as cut-offs. Nonparametric smoothing (generalised additive models) showed statistically significant confounder-adjusted associations between elevated CB-IgE levels (> or = 0.45 kU x L(-1)) and log-transformed exposures to cat (linear), mite (inverse u-shaped), and endotoxin (u-shaped). After adjustment for covariables, elevated CB-IgE levels (logistic regression using the 1st-4th quartiles of exposure) were positively associated with high cat-allergen exposure and medium exposure to mite allergen, but were inversely associated with exposure to endotoxin. The associations were similar, but somewhat weaker, when 0.35 kU x L(-1) was used as cut-off. These results, showing an association between prenatal allergen and endotoxin exposures and immunoglobulin E production, suggest that the development of foetal immune responses may be affected.

Dust mite allergens: ecology and distribution.

The most important allergy-causing mites found in homes worldwide are the house dust mites Dermatophagoides farinae, D. pteronyssinus, Euroglyphus maynei, and the storage mite Blomia tropicalis. Most homes contain multiple species. The most prevalent mite species and allergen in homes differ geographically, between homes within a geographical region, and among areas within a home. Therefore, it is important to know which mite species are present in a geographical area when performing diagnostic testing and prescribing immunotherapy. The key factor that influences mite survival and prevalence is relative humidity. Mites are present in homes in humid geographical areas and are rare or absent in drier climates unless humidity is artificially raised. Generally speaking, dust mite allergen levels are low in public buildings and transportation compared to levels in homes.

Exposure to dogs and cats in the first year of life and risk of allergic sensitization at 6 to 7 years of age.

Childhood asthma is strongly associated with allergic sensitization. Studies have suggested that animal exposure during infancy reduces subsequent allergic sensitization. To evaluate the relationship between dog and cat exposure in the first year of life and allergic sensitization at 6 to 7 years of age. Prospective birth cohort study of healthy, full-term infants enrolled in a health maintenance organization in suburban Detroit, Mich, who were born between April 15, 1987, and August 31, 1989, and followed up yearly to a mean age of 6.7 years. Of 835 children initially in the study at birth, 474 (57%) completed follow-up evaluations at age 6 to 7 years. Atopy, defined as any skin prick test positivity to 6 common aeroallergens (dust mites [Dermatophagoides farinae, D pteronyssinus], dog, cat, short ragweed [Ambrosia artemisiifolia], and blue grass [Poa pratensis]); seroatopy, defined as any positive allergen-specific IgE test result for the same 6 allergens or for Alternaria species. The prevalence of any skin prick test positivity (atopy) at age 6 to 7 years was 33.6% with no dog or cat exposure in the first year of life, 34.3% with exposure to 1 dog or cat, and 15.4% with exposure to 2 or more dogs or cats (P =.005). The prevalence of any positive allergen-specific IgE test result (seroatopy) was 38.5% with no dog or cat exposure, 41.2% with exposure to 1 dog or cat, and 17.9% with exposure to 2 or more dogs or cats (P =.003). After adjustment for cord serum IgE concentration, sex, older siblings, parental smoking, parental asthma, bedroom dust mite allergen levels at 2 years, and current dog and cat ownership, exposure to 2 or more dogs or cats in the first year of life was associated with a significantly lower risk of atopy (adjusted odds ratio, 0.23; 95% confidence interval, 0.09-0.60) and seroatopy (adjusted odds ratio, 0.33; 95% confidence interval, 0.13-0.83). Exposure to 2 or more dogs or cats in the first year of life may reduce subsequent risk of allergic sensitization to multiple allergens during childhood.

Concentration en allergènes majeurs d’acariens du groupe 1 dans la moquette : comparaison entre des chambres à coucher et des bureaux

Several studies have demonstrated the role of domestic exposure to mite in mite allergic patients. However, only one limited study have measured mite exposure at work in offices. The aim of our study was to compare group 1 mite allergen levels in carpets of offices and bedrooms. Thirty bedrooms and 27 offices were randomly selected. Dust samples were performed according to the international recommendations. Mite allergens were measured using ELISA based assay. A dramatic difference was found in group 1 mite allergen levels between bedrooms (mean: 18.4 μg/g) and offices (mean: 0.32 μg/g). We conclude that mite exposure in offices does not seem to be at risk for atopic and non atopic workers.

Feather bedding and house dust mite sensitization and airway disease in childhood

Feather bedding has been inversely associated with child wheeze and also with house dust mite (HDM) allergen levels. We conducted a cross-sectional analysis of the childhood component of a birth cohort study. Our aim was to examine the relation between feather bedding and HDM sensitization and airway disease. A total of 498 children (84% of eligible) residing in Northern Tasmania in 1997 who were eligible for the Tasmanian Infant Health Survey at birth in 1988 or 1989 participated. Outcome measures included atopic sensitization to Dermatophagoides farinae or Dermatophagoides pteronyssinus allergens, spirometric lung function, and child respiratory symptoms using questions from the ISAAC study. HDM sensitization was strongly associated with frequent wheeze (more than 12 episodes of wheeze compared with no wheeze in the past year) (rate ratio [RR], 19.61; confidence interval [CI], 6.94–55.56) but only weakly associated with asthma ever (RR, 1.65; CI, 1.30–2.09). Feather quilt use was associated with reduced HDM sensitization (adjusted RR [ARR], 0.60; CI, 0.45–0.80) and also reduced frequent wheeze episodes over the past year (ARR, 0.24; CI, 0.07–0.86). The reduction in wheeze was more evident among HDM-sensitized children. These findings are consistent with the possible mechanisms for feather bedding of a reduction in initial HDM sensitization and an improvement in respiratory symptoms among HDM-sensitized children. However, prospective studies are required to fully exclude selection bias.