House Dust Mite Levels Research Articles

Efficacy of Sublingual Immunotherapy in Allergic Rhinitis Children during Coronavirus Disease 2019

Background: Sublingual immunotherapy (SLIT) had good effectiveness for children with allergic rhinitis (AR). However, no studies explored the effect of persistent allergen exposure on SLIT treatment. Coronavirus disease 2019 (COVID-19) restricts outdoor activities of children significantly. We aimed to evaluate the effectiveness of SLIT during this special period. Methods: A total of 335 AR children who sensitize to house dust mite (HDM) undergoing SLIT were recruited in this study. The clinical effectiveness and safety were evaluated at different time points using symptom and medication scores. The serum total IgE and specific IgE (sIgE) at different time points were detected by using the Unicap system. Results: The total nasal symptoms score (TNSS) and total medication score (TMS) during the epidemic of COVID-19 increased significantly compared with the same period last year (p < 0.05), despite that they were still significantly lower than baseline levels (p < 0.05). The occurrence of adverse reactions at different time points had no significant differences. We also found that the family of the good response group had more frequent bedding cleaning. Both the tIgE and sIgE levels had no significant changes during SLIT treatment. Conclusion: Our results suggest that continuous HDM exposure reduced the effectiveness of SLIT, whereas effective reduction of HDM levels by frequent bed cleaning will be helpful during the SLIT treatment.

SERPINB10 contributes to asthma by inhibiting the apoptosis of allergenic Th2 cells

BackgroundSerine peptidase inhibitor, clade B, member 10 (SERPINB10) contributes to allergic inflammation in asthma. However, its role in the T-helper type 2 (Th2) response of allergic asthma is not known. The goal of this study was to unveil the function of SERPINB10 in the Th2 response of allergic asthma and the mechanism by which SERPINB10 affects the viability of Th2 cells.MethodsTh2 cytokines and serum levels of house dust mite (HDM)-specific IgE in bronchoalveolar lavage fluid were examined by ELISA in an HDM-induced asthma model. The number and apoptosis of Th1 and Th2 cells in mouse lungs were measured by flow cytometry. Naïve CD4 T cells from patients with asthma were cultured under appropriate polarizing conditions to generate Th1 and Th2 cells. SERPINB10 expression in polarized Th1 and Th2 cells was quantified by real-time reverse transcription-quantitative polymerase chain reaction. SERPINB10 expression was knocked down in human CD4 T cells with lentivirus.ResultsKnockdown of SERPINB10 expression significantly diminished HDM-induced Th2 cytokine secretion and level of HDM-specific IgE. After HDM exposure, SERPINB10-knockdown mice had diminished numbers of Th2 cells, but similar numbers of Th1 cells, compared with those in negative-control mice. Th2 cells of SERPINB10-knockdown mice were more susceptible to apoptosis than that of control mice. Stimulating T-cell receptors (TCRs) with anti-CD3 antibody caused upregulation of SERPINB10 expression in polarized Th2 cells, but not polarized Th1 cells. Knockdown of SERPINB10 expression resulted in fewer numbers and greater apoptosis of polarized Th2 cells.ConclusionOur results suggest that SERPINB10 may contribute to allergic inflammation and the Th2 response of asthma by inhibiting the apoptosis of Th2 cells.

Protein arginine methyltransferase 1 contributes to the development of allergic rhinitis by promoting the production of epithelial-derived cytokines

Arginine methylation is a posttranslational modification mediated by protein arginine methyltransferases (PRMTs). Although previous studies have shown that PRMT1 contributes to the severity of allergic airway inflammation or asthma, the underlying mechanism is poorly understood. This study aimed to explore the role of PRMT1 and its relevant mechanism in the development of allergic rhinitis (AR). The expression levels of PRMTs and cytokines were determined by RT-PCR, and the localization of PRMT1 was determined by immunohistochemistry and confocal microscopy. The levels of house dust mite (HDM)-specific immunoglobulins in serum and of cytokines in nasal lavage fluids were determined by ELISA. PRMT1 inhibition was achieved by siRNA andtreatment with the pan PRMT inhibitor arginine N-methyltransferaseinhibitor-1. PRMT1 expression was significantly increased in the nasal mucosa of patients and mice with AR. The degree of eosinophilic infiltration in the nasal mucosa was reduced in PRMT1+/- AR mice compared with wild-type mice. PRMT1 haploinsufficiency reduced the levels of HDM-specific immunoglobulins in serum and those of TH2 (IL-4, IL-5, and IL-13) and epithelial (thymic stromal lymphopoietin [TSLP], IL-25, and IL-33) cytokines in the nasal lavage fluids of AR mice. In nasal epithelial cells, HDM and IL-4 cooperate to enhance PRMT1 expression through a mitogen-activated protein kinase-dependent pathway. In addition, PRMT1 was essential for the production of TSLP, IL-25, and IL-33 in response to HDM and IL-4. Arginine N-methyltransferase inhibitor-1 treatment alleviated AR in the mouse model. PRMT1 plays an important role in AR development by regulating epithelial-derived cytokine production and might be a new therapeutic target for AR.

Grasshopper Sensitization In Patients Allergic To Crustaceans, House Dust Mite and Cockroach. Should Products Containing Grasshopper Come With A Warning?

We have previously described Anaphylaxis after first ingestion of grasshopper (GH) in patients who had a prior history of systemic reactions after eating crustaceans.These patients also had high levels of house dust mite (HDM) and cockroach(CR) allergy. The common cross reacting allergen was identified as Tropomyosin. In this abstract we report GH sensitivity in patients allergic to crustaceans, HDM and CR. Freeze-dried commercial GH (locusta migratoria) were made into a 1:10 w/v 50% glycerine in saline solution by the usual method. After obtaining informed written consent, patients and controls were skin tested (ST) by the Prick/puncture (PP) method to 1:10 w/v GH, and to 10 k AU HDM, 1:10 w/v lobster, 1:20 w/v crab and 1:10 shrimp extracts. Control patients who had negative ST to HDM, crustaceans, shrimp and crab, had negative ST to GH . Crustacean allergic patients showed 93.2% reactivity to GH. CR allergic patients 64.7% positive ST to GH and HDM positive patients 22.8% positive ST to GH. These results show a high % of ST reactivity to GH in patients who had no occupational nor recreational exposure to grasshoppers , but were sensitized to crustaceans, cockroach and HDM. These patients are potentially at risk for anaphylaxis if they eat GH. Recent reports of anaphylaxis to ingested grasshopper from China and Singapore, and the recent recommendation of the WHO advising entomophagy as a solution to world hunger, indicate the possibility of an increasing incidence of GH anaphylaxis. Should insect containing products carry a warning for allergic patients?

Asthma, Airway Symptoms and Rhinitis in Office Workers in Malaysia: Associations with House Dust Mite (HDM) Allergy, Cat Allergy and Levels of House Dust Mite Allergens in Office Dust.

A prevalence study was conducted among office workers in Malaysia (N= 695). The aim of this study was to examine associations between asthma, airway symptoms, rhinitis and house dust mites (HDM) and cat allergy and HDM levels in office dust. Medical data was collected by a questionnaire. Skin prick tests were performed for HDM allergens (Dermatophagoides pteronyssinus, Dermatophagoides farinae) and cat allergen Felis domesticus. Indoor temperature and relative air humidity (RH) were measured in the offices and vacuumed dust samples were analyzed for HDM allergens. The prevalence of D. pteronyssinus, D. farinae and cat allergy were 50.3%, 49.0% and 25.5% respectively. Totally 9.6% had doctor-diagnosed asthma, 15.5% had current wheeze and 53.0% had current rhinitis. The Der p 1 (from D. pteronyssinus) and Der f 1 (from D. farinae) allergens levels in dust were 556 ng/g and 658 ng/g respectively. Statistical analysis was conducted by multilevel logistic regression, adjusting for age, gender, current smoking, HDM or cat allergy, home dampness and recent indoor painting at home. Office workers with HDM allergy had more wheeze (p= 0.035), any airway symptoms (p= 0.032), doctor-diagnosed asthma (p= 0.005), current asthma (p= 0.007), current rhinitis (p= 0.021) and rhinoconjuctivitis (p< 0.001). Cat allergy was associated with wheeze (p= 0.021), wheeze when not having a cold (p= 0.033), any airway symptoms (p= 0.034), doctor-diagnosed asthma (p= 0.010), current asthma (p= 0.020) and nasal allergy medication (p= 0.042). Der f 1 level in dust was associated with daytime breathlessness (p= 0.033) especially among those with HDM allergy. Der f 1 levels were correlated with indoor temperature (p< 0.001) and inversely correlated with RH (p< 0.001). In conclusion, HDM and cat allergies were common and independently associated with asthma, airway symptoms and rhinitis. Der f 1 allergen can be a risk factor for daytime breathlessness.

Child car seats - a habitat for house dust mites and reservoir for harmful allergens.

House dust mites produce allergens which can cause or aggravate diseases such as asthma, eczema and rhinitis. The objectives of this study are to quantify typical house dust mite and Der p 1 allergen levels in child car seats, and to determine external variables that may influence mite populations in cars. Dust samples were collected from the child car seats and driver seats of 106 cars using a portable vacuum sampling pump over a two minute sampling period. Mites were counted and identified and results were expressed as mites per gram (mites/g) of dust, while Der p 1 content of samples were measured by enzyme-linked immunosorbent assay (ELISA). Questionnaires were completed by participants to identify environmental and behavioural effects on mite populations. Results were analysed using General Linear Model (GLM) procedures. Twelve species of mites, of which nine are known to produce harmful allergens, were recorded from 212 dust samples. Over 80% of drivers' seats and over 77% of child car seats harboured dust mites with a significant correlation (p = 0.001) between the mites/g of dust and Der p 1 content recovered from each seat. A mean of 53 mites/g of dust per seat was recovered, with a mean Der p 1 level of 1.1µg/g. Over 12% of driver seats and 15% of child car seats contained house dust mite levels sufficient to be risk factors for sensitisation and allergic reactions. Child car seats and driver seats are habitats to a range of mite species which can be present in sufficient concentrations to cause or aggravate allergen related illnesses in individuals who are genetically predisposed.

Indoor allergens in settled dust from kindergartens in city of Łódź, Poland

The main objective of the study was to determine the levels of house dust mite (Der p1), dog (Can f1), cat (Fel d1) and cockroach (Bla g2) allergens in kindergartens localized in an urban agglomeration. A quantitative analysis of allergens was carried out in settled dust samples collected by vacuuming the floor surface in three kindergartens (N = 84) and children's clothing (N = 36). The samples were collected in spring-summer and autumn-winter periods as well as at the beginning and end of the week. The allergen dust concentration was determined by enzyme-linked immunoenzymatic assay (ELISA). The mean geometric concentrations (±geometric standard deviations) of allergens Der p1, Can f1, Fel d1 and Bla g2 determined in kindergartens were: 0.02 ± 3.21 μg/g of dust; 0.97 ± 4.49 μg/g of dust; 0.30 ± 4.43 μg/g of dust and 0.01 ± 3.08 μg/g of dust, respectively. Younger classrooms (children aged from 3 to 4 years) were characterized by almost twice higher mean concentration of allergen Fel d1, as compared to older classrooms (children aged from 5 to 6 years) (p < 0.05). A significant impact of seasonality on the level of dog allergen Can f1 was found (p < 0.05). No significant weekly variation was found in average concentrations of the allergens. Children who had a dog and/or cat at home were characterized by high concentrations of allergens Can f1 and Fel d1 on their clothes (59.2 ± 5.39 μg Can f1/g of dust; 3.63 ± 1.47 μg Fel d1/g of dust), significantly higher than concentrations of allergens in children who did not have any pets (p < 0.001). Special attention should be paid to keeping the kindergarten rooms tidy and clean and to an appropriate choice of furnishings and fittings which would prevent the proliferation of the house dust mite and accumulation of allergens.

Arthropod Allergens in Urban Homes

Dust mites, cockroaches, and pets (cats, dogs) are common in homes worldwide, and many species are the source of potent allergens which cause allergic diseases. These diseases are influenced by genetic predisposition and environmental exposure. Generally, the levels of house dust mite (Der p 1 and Der f 1) and cockroach (Bla g 1, Bla g 2) allergens are used as markers of indoor exposure to arthropods.This article reviews the findings of allergens Der p 1, Der f 1, and Bla g 1 in randomly selected urban households in Zagreb (Croatia) measured from 2006 to 2010 and compares them with exposure to arthropod allergens in other countries. In short, house dust mite allergen levels in Croatian homes are low, but exposure is common; Der p 1 was found in 73 % and Der f 1 in 83 % of the households. By contrast, exposure to cockroach allergen Bla g 1 was both low and uncommon (13 %). Exposure to multiple allergens associated with sensitisation and asthma was not frequent in urban homes in Croatia. However, further studies should include monitoring of both arthropod and pet allergens in high-risk populations in inland and coastal Croatia. They should also investigate a complex dose-response relationship between exposure and sensitisation/asthma development, especially in early childhood.

The 8‐year follow‐up of the PIAMA intervention study assessing the effect of mite‐impermeable mattress covers

Exposure to high levels of house dust mite (HDM) allergens is associated with the development of allergic sensitization to HDM, a risk factor for the development of asthma, rhinitis, and allergic dermatitis. We studied the effect of an early intervention with mite-impermeable mattress covers on HDM allergen levels and the development of asthma and mite allergy throughout the first 8 years of life. High-risk children (allergic mother) were prenatally recruited and randomly allocated to two groups receiving mite allergen-impermeable (n = 416) and placebo mattress covers (n = 394) or no intervention (n = 472). Asthma and allergies were assessed yearly by questionnaire. Specific immunoglobulin E and bronchial hyper-responsiveness were measured at the age of 8 years. Mattress dust samples collected at different time points were analyzed for HDM allergens. At the age of 8 years, levels of HDM allergen Der f1 but not Der p1 were lower in the active than the placebo mattress cover group. In repeated measures analyses, we found a temporary decreased risk of asthma symptoms at the age of 2 years in the intervention group compared to the placebo group and a temporary association between higher HDM allergen exposure at the age of 3 months and more asthma symptoms. Early intervention with mite-impermeable mattress covers is successful in reducing exposure to Der f1; it only temporarily reduces the risk of asthma symptoms and does not reduce the risk of hay fever, eczema, and allergic sensitization.

Prevention of asthma in genetically susceptible children: A multifaceted intervention trial focussed on feasibility in general practice

Although the effectiveness of the multifaceted allergen-reducing interventions for the prevention of asthma in susceptible children was showed to be proven, the feasibility was not clear. The research question of the PREVention of asthma in susceptible children (PREVASC) trial was focused on the assessment of the effectiveness and feasibility of a multifaceted intervention on the prevention of allergic asthma in general practice. The effectiveness and feasibility of an intervention aimed at the simultaneous reduction in the environmental exposures to inhalant- and food allergens in susceptible children was investigated. A total of 476 children susceptible for developing asthma were initially included during pregnancy and were randomly divided over an intervention group of n = 222 children whose parents were offered a multifaceted environmental exposure-reducing intervention. Controls (n = 221) received usual care. The main outcome was 'diagnosis of allergic asthma at age 6'. A significant reduction in inhalant allergen exposure levels of house dust mite [(Der p1), p = 0.043], cat [(Fel d1), p = 0.037], and dog [(Can f1), p = 0.012] was reached. Significantly more intervention group children started using cow's milk and solids after the age of 6 months (p ≤ 0.001). No statistical difference, however, was reached between groups on the duration of breast-feeding (p = 0.635) and the reduction in smoke exposure (p = 0829). At age 6, the intervention had no influence on the development of main outcome allergic asthma (OR = 1.010 (CI 0.580-1.758). Other primary preventive asthma-reducing interventions were shown to be effective in reducing the occurrence of asthma for at least the first 7-8 yr of life. The multifaceted PREVASC allergic asthma primary preventive intervention was effective in reducing the exposure to inhalant and food allergens, but was not feasible for the parents. A lack of sufficient room for improvement focus on stimulating adherence seemed to be involved. It is suggested that a multifaceted environmental exposure-reducing intervention may have to be adapted to the personal circumstances of patients at baseline.

Cockroach exposure independent of sensitization status and association with hospitalizations for asthma in inner-city children

Children with asthma living in urban environments experience disproportionately high asthma hospitalization rates. Excessive exposure to perennial allergens, including cockroach and house dust mite (HDM), have been implicated, but data are limited. To examine the relation between cockroach and HDM exposure and measures of asthma morbidity and health care utilization. Participants included 86 atopic asthmatic children living in New Orleans, Louisiana. Sensitization status was determined by means of serum specific IgE testing, and vacuum dust samples were collected for allergen analysis. Logistic regression analysis was used to assess the odds of persistent wheezing, emergency department visits, and asthma hospitalization in those with high vs low levels of allergen exposure. Approximately 44% and 40% of children were exposed to Bla g 1 levels greater than 2 U/g and HDM levels greater than 2 μg/g, respectively, and 24% reported at least 1 hospitalization in the previous 4 months. The median Bla g 1 level was significantly higher in the homes of children hospitalized compared with those with no hospital admissions (7.2 vs 0.8 U/g). In multivariable models, the odds of hospitalization were significantly higher in children exposed to Bla g 1 levels greater than 2 U/g (adjusted odds ratio, 4.2; 95% confidence interval, 1.24-14.17), independent of sensitization status. Exposure to HDMs was not associated with any measure of morbidity. Exposure to cockroach allergen was strongly associated with increased hospitalization in children with asthma. This effect cannot be explained entirely by IgE-mediated inflammation. Controlled interventional trials are needed to determine whether isolated cockroach abatement improves asthma control.

Update on the pathogenesis and management of childhood asthma

To review and summarize trends in the current literature in childhood asthma with implications for current management and future research. There have been several articles in the last year that address the pathogenesis and pharmacogenomics of asthma. Recent consensus guidelines have been published that emphasize a stepwise approach to management, which will be briefly reviewed here. Several publications have proposed novel treatments to attempt to attenuate asthmatic lower airway inflammation. In terms of measuring this inflammation, a portable exhaled nitric oxide analyzer has been developed. Evidence shows that various early life exposures (high house dust mite levels, early antibiotic use) may predispose susceptible individuals to the development of asthma, but the early introduction of solid foods, even so-called allergenic foods, does not appear to be one of these factors. Newly identified pharmacogenomic markers may be the first step in tailoring each asthmatic patient's therapy on the basis of genotype, and management tailored specifically toward each patient's level of airway inflammation is already coming into wider clinical use. Several novel treatments for asthma have shown promise in early studies. On the basis of the most recent evidence, the National Education and Prevention Program's Guidelines for the Diagnosis and Management of Asthma is a comprehensive, stepwise management guide for asthma.

The bell tolls for the relationship between house dust mite exposure and asthma in childhood

Prior evidence has suggested a direct relationship between the level of house dust mite (HDM) allergen exposure, sensitisation and asthma. A recent cross-sectional study indicated a bell-shaped relationship between HDM exposure and sensitisation [1]. We examined the effects of cumulative HDM allergen exposure during the first 5 years of life on outcomes at age 5 years in Sydney, a high HDM environment.In the Childhood Asthma Prevention Study, bed dust samples collected at 3, 6, 9 and 12 months and then 6-monthly (total 6615 samples) until age 5 years were analysed for HDM allergen by ELISA. At five years, 516 children were assessed for wheeze and asthma by questionnaires and spirometry, and 488 for sensitisation by skin test. Time-weighted average HDM allergen concentration was estimated for each individual. The range was divided into quintiles with cut-points being 3,5; 7,8; 13,5 and 23,4 ug Der p 1/g. The association between HDM levels and outcomes was analysed with chi-square test, adjusting for confounders.The figure shows the prevalence of outcomes by quintile of time-weighted average of HDM allergen.In this birth cohort, there is a bell-shaped dose response between HDM levels and sensitisation and asthma. This may reflect tolerance to HDM allergen or be attributable to protection from associated exposures, and prompts further research on the mechanisms.

Early allergen exposure and atopic eczema

The relationship between exposure to indoor aeroallergens in early life and subsequent eczema is unclear. We have previously failed to show any significant associations between early life exposure to house dust mite and cat fur allergens and either sensitization to these allergens or wheeze. We have also previously reported a lower prevalence of parent-reported, doctor-diagnosed eczema by age 2 years for children exposed to higher concentrations of house dust mite, but no other associations with other definitions of eczema or for exposure to cat allergen. To extend the exposure-response analysis of allergen exposure and eczema outcomes measured up to age 8 years, and to investigate the role of other genetic and environmental determinants. A total of 593 children (92 x 4% of those eligible) born to all newly pregnant women attending one of three general practitioner surgeries in Ashford, Kent, were followed from birth to age 8 years. Concentrations of house dust mite and cat allergen were measured in dust samples collected from the home at 8 weeks after birth. The risk of subsequent eczema as defined by the U.K. diagnostic criteria was determined according to different levels (quintiles) of allergen exposure at birth. By age 8 years, 150 (25 x 3%) children had met the diagnostic criteria for eczema at least once. Visible flexural dermatitis was recorded at least once for 129 (28 x 0%). As in other studies, parental allergic history was positively associated with most eczema outcomes, as were higher maternal education and less crowded homes. No clear linear associations between early exposure to house dust mite or cat allergen were found, regardless of the definition of eczema used. The risk of eczema appeared to increase for the three lowest quintiles of house dust mite allergen exposure (odds ratio, OR 1 x 37 for third quintile compared with first), and then to fall for the two highest quintiles (OR 0 x 66 and 0 x 71) even after controlling for confounding factors. The lack of any clear exposure-disease relationship between allergens in early life and subsequent eczema argues against allergen exposure being a major factor causing eczema. If the lower levels of eczema at higher levels of house dust mite are confirmed, then interventions aimed at reducing house dust mite in early infancy could paradoxically increase the risk of subsequent eczema.

The effect of home characteristics on dust antigen concentrations and loads in homes.

On-site home visits, consisting of a home inspection, dust sampling, and questionnaires were conducted in 777 homes belonging to an ongoing birth cohort study in Cincinnati, Ohio. Various home characteristics were investigated, and antigen levels (concentrations [microg/g] and loadings [microg/m(2)]; IU for cockroach allergen) in floor dust samples collected in child's primary activity room were analyzed by ELISA. Monoclonal antibodies were used for the analysis of cat, house dust mite, and cockroach allergens, and polyclonal antibodies for Alternaria and dog antigens. The relationship between the antigen levels and home characteristics was investigated through a generalized multiple regression model. More than half of the homes experienced mold/water damage. Cats and dogs were present in 19.7% and 31.1% of homes, respectively. More than 90% of homes had either carpet or area rug covering their floors. Among 777 homes, 87-92% of homes had measurable amount of Alternaria, cat, and dog allergen/antigen in house dust, whereas only 38% and 14% of homes had measurable levels of house dust mite and cockroach, respectively. Alternaria antigen level in house dust was not associated with visual mold/water damage, which was suspected to be one of the sources for this antigen in homes. Instead, the antigen level was high in samples taken in fall and in homes having dogs implicating that Alternaria antigen appears to be transported from outdoors to indoors. A high level was also measured in homes using a dehumidifier (these homes have experienced excessive humidity) and in-home venting of clothes dryer, which might be associated with microclimate affecting mold growth and spore release. The allergen/antigen level (both concentration and loading) of cat, dog and cockroach was significantly associated with the number of cats and dogs, or the appearance of cockroaches, respectively. High level of house dust mite allergen was measured in bedrooms and in homes using dehumidifier and no central forced air heating system. Having indoor plants was shown to reduce allergen levels. Carpeted floor was found to hold larger amount of antigens than non-carpeted floor. Antigen loading demonstrated more consistent and larger numbers of associations with home characteristics compared to antigen concentration. This study encompassed a wide range of home characteristics and various antigen types. Our findings provide information on home characteristics that can be used for allergen avoidance and in planning future exposure assessment studies.

Infant Sleeping Environment and Asthma at 7 Years: A Prospective Cohort Study

We investigated the role of infant bedding items, as part of a composite bedding environment, in the development of childhood wheezing. This prospective cohort investigation involved 863 children who participated in an infant survey in 1988 and an asthma study in Tasmania, Australia, in 1995. The derived 3 composite infant bedding categories corresponded to increasing numbers of house dust mite (HDM)-rich bedding items used. Outcomes measured included recent and frequent wheezing. Composite infant bedding used was associated with recent wheezing. Effects increased at increasing levels of HDM-rich bedding items used. Effects were further enhanced by home environmental factors of bedroom heating, recent bedroom painting, and absence of bedroom carpeting. When any 2 or more of these environmental factors were present, a strong dose-response relationship was evident. Our results show that bedding exposures in infancy are prospectively associated with childhood wheezing and that home environmental conditions may modify this association.

Are house dust mite allergen levels influenced by cold winter weather?

Moisture is vitally important for house dust mites and they cannot survive in cold or hot-dry climates. To investigate the influence of two extraordinarily cold and dry winters in 1995/1996 and 1996/1997 on house dust mite levels in German homes. Dust samples were collected between June 1995 and December 2001 on the mattresses of 655 adults and 454 schoolchildren living in five different areas of Germany. We compared house dust mite allergen Dermatophagoides pteronyssinus (Der p 1) levels before and during the winters of 1995/1996 and 1996/1997 with levels after these winters. D. pteronyssinus (Der p 1) levels in samples taken after the cold winters of 1995/1996 and 1996/1997 were approximately two times lower than Der p 1 levels in dust samples collected before or during these respective winters (Geometric means: Erfurt 89 vs 33 ng/g; Hamburg 333 vs 219 ng/g; Bitterfeld, Hettstedt, and Zerbst 296 vs 180 ng/g). Except for Hamburg, the decrease in Der p 1 levels was statistically significant. D. pteronyssinus levels measured in dust samples collected in 2001 (i.e. 3 years after the two cold winters) show a statistically non-significant increase (Geometric means: Erfurt 33 vs 39 ng/g; Hamburg 219 vs 317 ng/g), suggesting that it may take a long time for mite allergen levels to increase again after a sudden decrease. We conclude that Der p 1 levels in German mattress dust samples have been approximately reduced by a factor of three to four by the two consecutive cold winters of 1995/1996 and 1996/1997.

EFFECT OF MATTRESS AND PILLOW ENCASINGS ON CHILDREN WITH ASTHMA AND HOUSE DUST MITE ALLERGY

Halken S, Host A, Niklassen U, et al. J Allergy Clin Immunol. 2003;111:169–176 Allergy to house dust mite (HDM) is an important contributor to childhood asthma, and these investigators sought to determine whether the use of mattress and pillow encasings resulted in effective long-term control of mattress HDM levels, thus reducing the need for maintenance asthma medication. The subjects were 60 children (5–15 years of age) with asthma and HDM allergy, in the absence of any other clinically relevant allergy. Inclusion criteria included physician-diagnosed asthma, positive HDM puncture skin test results, positive …

EFFECT OF MATTRESS AND PILLOW ENCASINGS ON CHILDREN WITH ASTHMA AND HOUSE DUST MITE ALLERGY

Halken S, Host A, Niklassen U, et al. J Allergy Clin Immunol. 2003;111:169–176Allergy to house dust mite (HDM) is an important contributor to childhood asthma, and these investigators sought to determine whether the use of mattress and pillow encasings resulted in effective long-term control of mattress HDM levels, thus reducing the need for maintenance asthma medication.The subjects were 60 children (5–15 years of age) with asthma and HDM allergy, in the absence of any other clinically relevant allergy. Inclusion criteria included physician-diagnosed asthma, positive HDM puncture skin test results, positive HDM bronchoprovocation results, and total HDM concentrations of ≥2000 ng/g dust from the child’s mattress. All except 4 of the study patients were treated with inhaled corticosteroids.In this prospective, double-blind, placebo-controlled, 1-year study, children were randomized to the use of active (allergy control) or placebo mattress and pillow encasings. Baseline measures included mattress dust sampling, spirometry, and adjustment of medications. Symptom scores and peak flows were recorded throughout the study. Clinical assessments, including medication adjustments, and dust sampling were performed every 3 months. Bronchoprovocation was performed at the time of inclusion and at completion of the study.Twenty-six children in the active treatment group and 21 children in the placebo group completed the study. A significant perennial reduction in levels of HDM allergen recovered from mattresses was noted only for the active treatment group. Significant decreases in the doses of inhaled corticosteroids also were noted only for the active treatment group. There were no significant differences between the active treatment and placebo groups in any of the secondary endpoints, including peak flow and forced expiratory volume in 1 second, symptoms, and HDM bronchoprovocation results.The use of mattress and pillow encasings led to significant long-term reductions in HDM allergen levels in mattresses and in the need for inhaled corticosteroids among children with asthma and HDM allergy.Greater HDM allergen exposure in childhood is associated with more severe asthma. However, it has been difficult to demonstrate in clinical studies that HDM avoidance is both achievable and associated with subsequent clinical improvement. This is not surprising, given the ubiquitous nature of HDMs and concomitant exposure to other contributing allergens. These authors chose their patient population carefully, to allow greater focus on the allergens in question. The 1-time cost of these encasings is approximately equal to the cost of 1 month of asthma drug therapy in the United States, and encasings are labor- and risk-free. They should be made available to HDM-allergic persons of all ages unless there is compelling evidence against them, which there is not currently. The same cannot be said for measures such as duct cleaning and the use of special filters, which likely have very little effect on either the ambient load of HDM allergen or clinical status.

House dust mites (Der p 1, Der f 1), cat (Fel d 1) and cockroach (Bla g 2) allergens in indoor work-places (offices and archives)

Background: Exposure to indoor allergens has already been shown to occur in many public places, including workplaces, in several countries. Aim of this study was to measure the levels of house dust mites, cat and cockroach allergens in indoor workplaces (offices and archives) in Italy and to evaluate the possible relationships between allergen levels and building characteristics, type of ventilation, indoor relative humidity and temperature. Methods: Der f 1 and Der p 1, Fel d 1, Bla g 2 were measured by ELISA in dust samples collected from floors or upholstered seats of 160 workplaces. Results: Detectable Der p 1 levels were found in 86 (54%) workplaces Der f 1 in 87 (55%), Fel d 1 in 86 (54%) and Bla g 2 in 3 (1.9%). Der p 1 allergen concentrations expressed per weight were higher than the proposed sensitization thresholds in 7 samples, Der f 1 in 5, Fel d 1 in 6 and Bla g 2 in 3. The highest allergen levels were detected in samples from upholstered seats. A significant correlation was found between Der f 1 level on floors, expressed per surface, and indoor temperature ( r=0.39; P<0.01). Conclusions: In our study we found that upholstered seats in workplaces in Italy may constitute a significant reservoir both of house dust mites and cat allergens. Exposure to these allergens in workplaces may represent a risk factor for elicitation of symptoms and/or induction/maintenance of inflammation in allergic individuals and might also constitute a risk factor for sensitization.