Dust Mite Allergen Levels Research Articles

Residual profiles and health risk of indoor allergens in China

Exposure to indoor allergens is a principal risk factor for allergic diseases. However, most of the previous studies on indoor allergens focused on very limited kinds of allergens in China. Knowledge of the simultaneous exposure to multiple allergens is still lacking. In this study, the residual profiles of 8 allergens were investigated in 166 dust samples from 11 cities in China. The house dust mite allergens including Der p 1, Der f 1, and Der 2 were detected in the range of <0.02–283.83 μg/g dust. The concentrations of dog allergen Can f 1 and cat allergen Fel d 1 varied widely, from <0.84–22,896.46 μg/g dust for Can f 1 and from <0.02–6298.96 μg/g dust for Fel d 1. Cockroach allergen Bla g 2 was detected in 68% of the samples but at a low level with a maximum of 9.44 μg/g dust. Comparatively low detection frequencies were found for mouse allergen Mus m 1 as 37% and for fungi allergen Asp f 2 as 24%. The frequency of cleaning sheets/bedding was negatively correlated to the levels of house dust mite allergens. The presence of pets indoors was associated with higher levels of pet allergens and lower levels of house dust mite allergens and cockroach allergen. Risk evaluation reveals that at least 4 allergens were found in more than 80% of the rooms and more than 2 allergens with median/high risk were detected in 42% of the rooms, indicating that simultaneous exposure to multiple allergens is prevalent in China.

Occupants' Health and Their Living Conditions of Remote Indigenous Communities in New Zealand.

The New Zealand Ministry of Health reported that respiratory disease affects 700,000 people, annually costs New Zealand NZ$7.05 billion, and is the third-highest cause of death. The hospitalisation rate for asthma of Māori communities is 2.0 higher than that of other ethnic groups, and hospitalisation rates for deprived homes are 2.3 times higher than those of the least deprived homes. Based on physical data and evidence, which were drawn from a mixed methodology that includes field studies of the indoor microclimate, dust-mite allergens, mould growth, and occupants’ Respiratory Health Survey of a number of sample houses of Māori communities in Minginui, Te Whaiti, Murupara, and Rotorua of New Zealand, the study identifies unhealthy indoor thermal conditions, thresholds or ranges of indoor micro-climate related to different levels of dust-mite allergen and mould growth, the most common type of indoor mould, and correlations between dust-mite and mould and correlations. The study not only identified that the poor health of occupants is closely related to their inadequate living conditions, but also identifies the threshold of indoor micro-climates to maintain indoor allergens at the acceptable level, which can be used as a guideline to maintain or improve indoor health conditions for future housing development or retrofitted old housing.

House Dust Mite Allergen Levels of Der p1 and Der f1 in Houses of Asthmatic Children

Background: Exposure to house dust mites is an important cause of asthma among children. The main asthma-causing mites found in homes are Dermatophagoides farinae and Dermatophagoides. pteronyssinus. Der f1 or Der p1 are allergens of the mentioned mites. This study aimed to assess the levels of Der p1, and Der f1 in the homes of families that had a case of childhood asthma in a northern city of Iran and to determine the association between indoor house environment and the level of mites allergens present there. Objectives: This study aimed to evaluate House Dust Mite Allergen Levels of Der p1 and Der f1 in Houses of Asthmatic Children. Methods: Dust samples were collected from bedrooms of 91 homes of families that had cases of childhood asthma. Families filled a questionnaire about demographical characteristics and the indoor condition of their living environment. The levels of Der f1 and Der p1 were measured by enzyme-linked immunosorbent assay (ELISA). Statistical analysis was performed in SPSS v. 24 and a P-value less than 0.05 was considered significant. Results: we found that Der p1 was more prevalent than Der f1 among samples. The mean concentration of Der p1 concentration was 271.35 ng/g (9 times greater than the concentration of Der f1). When the indoor environment status was evaluated, it was found that keeping pets and having old carpets are associated with Der f1 (P&lt;0.05). However, no significant association was found between Der p1 and the indoor conditions of the home. Conclusions: Our study showed that Der p1 level is higher than Der f1 level in the houses of children with asthma. We suggest removing carpets and pets from the house.

Effects of Air Pollution and Land Use Characteristics on Development and Respiratory Health among Children in the Greater Taipei Area

Indoor and outdoor air pollution poses an important health threat to children. Exposure to air pollution may cause various acute and chronic respiratory diseases, and affect neurodevelopment and cognitive functions in children. To evaluate the impact of air pollution on children's health, we conduct a study to examine the effect of prenatal and early childhood exposure to air pollution on development and respiratory health in the first 3 years of life among a birth cohort in the Greater Taipei area. We will recruit 500 cohort children, and evaluate their development and respiratory diseases using standardized questionnaires and Bayley Scales of Infant and Toddler Development. One hundred children will be selected to conduct indoor and outdoor environmental samplings of their residences. Four hundred and fifty-six cohort children have been recruited so far, and environmental measurements have been implemented in 40 homes. According to our analyses, most ambient pollutant concentrations near participants' homes were lower than Taiwan National Ambient Air Quality Standard, expect PM2.5, which exceeded the annual average level (15µg/m3). A few households had elevated indoor pollution levels due to a low ventilation rate or recent remodeling. Several children's bed dust samples contained dust mite allergen levels &amp;gt; 2 µg/g, which may increase the risk of child sensitization to dust mites. According to multiple regression analyses, a high level of nitrogen oxides during first trimester near residence as well as living near gas stations, social welfare facilities, or high ways had adverse effects on children's health; living near green parks was beneficial to children's neurodevelopment. Overall, residential environments, such as air quality and land use type nearby, may significantly influence children's health and neurodevelopment.

Plasma Cluster Ions Reduce the IgE-Binding Capacity of House Dust Mite Allergens under a Simulated Indoor Environmental Condition

Background: A high level of house dust mite (HDM) allergens in a living environment is a risk factor for both sensitization to these allergens and asthmatic attacks. We previously showed that plasma cluster ions (PCIs) impaired the IgE-binding capacity of atomized crude allergens prepared from Japanese cedar pollen and fungus under experimental conditions. Objective: We evaluated the capacity of PCIs to impair the IgE-binding capacity of airborne HDM allergens under a simulated indoor environmental condition. Methods: For the determination of the effects of PCIs on HDM allergens under an experimental condition, HDM extract was atomized as aqueous mist into a cylindrical experimental apparatus filled with PCIs. For the evaluation of the effects of PCIs under a simulated natural indoor environmental condition, dried HDM allergens were floated as airborne particles in an acryl cubic apparatus in the presence of PCIs. The IgE-binding capacities of the PCI- and sham-treated HDM allergens were analyzed by an ELISA. Results: The IgE-binding capacity of the HDM allergens was significantly impaired after PCI treatment compared to that after sham treatment under both experimental and simulated environmental conditions. The ELISA results demonstrated that the IgE-binding capacities of HDM allergens after PCI treatment showed 68 and 74% reductions compared to those after sham treatment under the experimental and simulated environmental conditions, respectively. Conclusions: PCIs have the capacity to impair the IgE-binding capacity of airborne HDM allergens in a simulated environmental condition.

NIAID, NIEHS, NHLBI, and MCAN Workshop Report: The indoor environment and childhood asthma—implications for home environmental intervention in asthma prevention and management

Environmental exposures have been recognized as critical in the initiation and exacerbation of asthma, one of the most common chronic childhood diseases. The National Institute of Allergy and Infectious Diseases; National Institute of Environmental Health Sciences; National Heart, Lung, and Blood Institute; and Merck Childhood Asthma Network sponsored a joint workshop to discuss the current state of science with respect to the indoor environment and its effects on the development and morbidity of childhood asthma. The workshop included US and international experts with backgrounds in allergy/allergens, immunology, asthma, environmental health, environmental exposures and pollutants, epidemiology, public health, and bioinformatics. Workshop participants provided new insights into the biologic properties of indoor exposures, indoor exposure assessment, and exposure reduction techniques. This informed a primary focus of the workshop: to critically review trials and research relevant to the prevention or control of asthma through environmental intervention. The participants identified important limitations and gaps in scientific methodologies and knowledge and proposed and prioritized areas for future research. The group reviewed socioeconomic and structural challenges to changing environmental exposure and offered recommendations for creative study design to overcome these challenges in trials to improve asthma management. The recommendations of this workshop can serve as guidance for future research in the study of the indoor environment and on environmental interventions as they pertain to the prevention and management of asthma and airway allergies.

Genome-wide interaction study of dust mite allergen on lung function in children with asthma

Childhood asthma is likely the result of gene-by-environment (G×E) interactions. Dust mite is a known risk factor for asthma morbidity. Yet, there have been no genome-wide G×E studies of dust mite allergen on asthma-related phenotypes. We sought to identify genetic variants whose effects on lung function in children with asthma are modified by the level of dust mite allergen exposure. A genome-wide interaction analysis of dust mite allergen level and lung function was performed in a cohort of Puerto Rican children with asthma (Puerto Rico Genetics of Asthma and Lifestyle [PRGOAL]). Replication was attempted in 2 independent cohorts, the Childhood Asthma Management Program (CAMP) and the Genetics of Asthma in Costa Rica Study. Single nucleotide polymorphism (SNP) rs117902240 showed a significant interaction effect on FEV1 with dust mite allergen level in PRGOAL (interaction P=3.1×10-8), and replicated in the same direction in CAMP white children and CAMP Hispanic children (combined interaction P=.0065 for replication cohorts and 7.4×10-9 for all cohorts). Rs117902240 was positively associated with FEV1 in children exposed to low dust mite allergen levels, but negatively associated with FEV1 in children exposed to high levels. This SNP is on chromosome 8q24, adjacent to a binding site for CCAAT/enhancer-binding protein beta, a transcription factor that forms part of the IL-17 signaling pathway. None of the SNPs identified for FEV1/forced vital capacity replicated in the independent cohorts. Dust mite allergen exposure modifies the estimated effect of rs117902240 on FEV1 in children with asthma. Analysis of existing data suggests that this SNP may have transcription factor regulatory functions.

Evaporative Cooler Use Influences Temporal Indoor Relative Humidity but Not Dust Mite Allergen Levels in Homes in a Semi-Arid Climate

Concerns about energy consumption and climate change make residential evaporative coolers a popular alternative to central air conditioning in arid and semi-arid climates. However, evaporative coolers have been shown to significantly increase indoor relative humidity and dust mite allergen levels in some studies, while showing no association in other studies. Improved measurement of temporal fluctuations in indoor relative humidity may help identify factors that promote mite growth in homes in dry climates. Dust samples and continuous indoor relative humidity measurements were collected from homes with central air conditioning and homes with evaporative coolers in Utah. Samples were collected over two seasons, winter/spring (Jan–Apr) and summer (July–Sept), 2014. Dust samples were analyzed for Der p 1 and Der f 1 using a two-site monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA) analysis. Housing characteristics including age of home, occupant density, and age of mattresses, furniture, and carpeting were also measured. Positive Der p 1 or Der f 1 samples were found in 25.0% of the homes and there was no difference in mean allergen levels by type of air conditioning. Indoor relative humidity was significantly higher in homes with evaporative coolers compared to those with central air conditioning during the summer. Homes with evaporative coolers also spent significantly more time during summer above 55.0% and 65.0% relative humidity compared to central air homes, but not above 75.0%. Findings from this study suggest that increased humidity from evaporative coolers may not be sufficient to exceed the critical equilibrium humidity or maintain humidity excursions for sufficient duration in relatively larger single-family homes in semi-arid climates to support mite growth and reproduction.

Efficacy of an in-home test kit in reducing dust mite allergen levels: results of a randomized controlled pilot study

Background: Dust mite allergens can induce allergic sensitization and exacerbate asthma symptoms. Although dust mite reduction and control strategies exist, few asthmatics employ them. Objectives: We examined whether an in-home test kit, which quantifies dust mite allergen levels, resulted in behavioral changes in implementation and maintenance of mite reduction strategies and helped reduce allergen levels in homes of dust mite-sensitive children. Methods: We enrolled 60 households of children aged 5–15 with parent-reported dust mite allergy into a randomized controlled trial. Intervention homes (N = 30) received educational material about reducing dust mites and test kits at 1, 2, 5 and 8 months. Control homes (N = 30) received only educational material. At baseline, 6 and 12 months, study staff visited all homes, collected dust samples from three locations and obtained information about parents’ mite reduction behaviors by questionnaire. Allergen concentrations (Der f 2/Der p2) in dust were assessed by immunoassays. After adjusting for visit and location, allergen concentrations in intervention and control homes were compared using mixed effects model analysis. Results: In the intervention homes, allergen concentrations in the child’s bedroom and living room floors were significantly reduced over time compared to control homes. Although not all location-specific differences in allergen concentrations were statistically significant, combining data across locations, there was a differential reduction in allergen concentrations in the intervention group versus the control group (p = 0.02). Conclusion: The use of in-home test kits along with education may beneficially influence behaviors and attitudes toward dust mite reduction strategies and help reduce residential dust mite allergen levels.

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.

Genome-wide expression profiles identify potential targets for gene-environment interactions in asthma severity

Gene-environment interaction studies using genome-wide association study data are often underpowered after adjustment for multiple comparisons. Differential gene expression in response to the exposure of interest can capture the most biologically relevant genes at the genome-wide level. We used differential genome-wide expression profiles from the Epidemiology of Home Allergens and Asthma birth cohort in response to Der f 1 allergen (sensitized vs nonsensitized) to inform a gene-environment study of dust mite exposure and asthma severity. Polymorphisms in differentially expressed genes were identified in genome-wide association study data from the Childhood Asthma Management Program, a clinical trial in childhood asthmatic patients. Home dust mite allergen levels (<10 or ≥10 μg/g dust) were assessed at baseline, and (≥1) severe asthma exacerbation (emergency department visit or hospitalization for asthma in the first trial year) served as the disease severity outcome. The Genetics of Asthma in Costa Rica Study and a Puerto Rico/Connecticut asthma cohort were used for replication. IL9, IL5, and proteoglycan 2 expression (PRG2) was upregulated in Der f 1-stimulated PBMCs from dust mite-sensitized patients (adjusted P < .04). IL9 polymorphisms (rs11741137, rs2069885, and rs1859430) showed evidence for interaction with dust mite in the Childhood Asthma Management Program (P = .02 to .03), with replication in the Genetics of Asthma in Costa Rica Study (P = .04). Subjects with the dominant genotype for these IL9 polymorphisms were more likely to report a severe asthma exacerbation if exposed to increased dust mite levels. Genome-wide differential gene expression in response to dust mite allergen identified IL9, a biologically plausible gene target that might interact with environmental dust mite to increase severe asthma exacerbations in children.

House Dust Mite Allergen Exposure in Adults Is Associated with Strong Specific Sensitization But Not with Clinical and Functional Respiratory Health Outcomes

Background: Exposure to house dust has been associated with asthma in adults, and this is commonly interpreted as a direct immunological response to dust mite allergens in those who are IgE sensitised to house dust mite (HDM). Objectives: The aim of this analysis is to utilise information collected as part of a large international observational multicentre study in order to explore, in adults, associations of respiratory symptoms, including severity of symptoms with mattress house dust mite allergen levels. Methods: Mattress house dust mite concentrations were measured in a population based sample of 2890 adults aged between 27 and 56 years living in 22 centres in 10 countries. Generalized linear mixed models were employed to explore the association of respiratory symptoms with house dust mite concentrations, adjusting for individual and household confounders. Results: There was no overall association of respiratory outcomes with measured house dust mite concentrations, even in those who reported they had symptoms on exposure to dust and those who had physician diagnosed asthma. There was an association of high serum specific IgE levels to HDM (&gt; 3.5 kUA/L) with mattress house dust mite concentrations. Conclusions: In conclusion, in a large international cross-sectional survey of adults there was evidence of an association of house dust mite concentrations with high levels of serum specific IgE to HDM, but not with clinical and functional respiratory health outcomes.

House dust mite allergen levels in households and correlation with allergic rhinitis symptoms.

House dust mite (HDM) allergen is a risk factor for the development of allergic rhinitis (AR). To determine the levels of indoor allergens in the households of patients with AR in Wuhan city, identify the environmental risk factors for high allergen exposure, and investigate the correlations between allergen exposure and specific immunoglobulin E levels and symptoms. The study examined 50 patients with AR. Two dust samples were collected from the bedding of each patient, one in summer and one in winter. Major allergens Der p 1 and Der f 1, from Dermatophagoides pteronyssinus and Dermatophagoides farinae, were measured with an enzyme-linked immunosorbent assay. Participants completed a standardized questionnaire about their living environments, and their rhinitis symptom scores were calculated. Specific immunoglobulin E levels against Der p and Der f were measured. The percentage of bedding samples with high HDM allergen (Der f 1 + Der p 1) levels (>10 μg/g) was 44% in summer and 46% in winter. There was no significant difference between the level of mite allergens in summer and winter; however, the level of Der f 1 was higher than that of Der p 1 (p < 0.05). The age of the mattress and pillow was significantly correlated with allergen concentration. Indoor HDM allergen level affected the severity of nasal itching. HDMs are important indoor allergens in Wuhan. Mattresses and pillows that have been used for a long time contain high levels of allergens. High levels of exposure to HDM allergens correlates with the severity of nasal itching.

P79 ‐ AsthmaVent – effect of mechanical ventilation on asthmacontrol in house dust mite allergic children with asthma

Background House dust mite allergy is a frequent cause of asthma in children. Children with house dust mite allergy and asthma are especially sensitive to physical and chemical agents in the indoor air and as children spend a lot of time indoors, it seems reasonable to believe that improving the indoor environment will lead to an improvement in asthma disease. At present, there is no clear consensus on the effect of ventilation on asthmatic children with house dust mite allergy. Earlier studies have been criticized for being small, poorly carried out and inconclusive. Thus there is a need for a powerful and methodologically rigorous study to provide significant evidence as a basis for the future treatment of children with house dust mite allergy and asthma. Objective This study started in the fall 2012 and aims at investigating whether mechanical ventilation is able to improve asthma symptoms during the winter season for children with house dust mite allergy and asthma. Materials and methods The study is a randomized double-blind placebocontrolled intervention study, with 9 months of intervention and follow-up. 80 children are included from 3 Danish hospitals and are randomized into two groups. The intervention is mechanical ventilation in the child’s bedroom. We monitor indoor air quality and health outcomes every three months. Primary outcomes are minimal effective dose of inhalation steroids and reduction in levels of particulate matter and house dust mite allergen. Perspectives Asthma patients and their families rely on good evidencebased advice on behavior and design of housing, so that the specific and non-specific factors in the indoor environment that trigger the disease are controlled as well as possible. The results of this project will be a significant contribution to the recommendations that can be given in relation to the effect of ventilation on indoor air quality in the asthma control of house dust mite allergic children.

Cat, dog and house dust mite allergen levels on children’s soft toys

Objective: Children’s soft toys are known to harbour house dust mite (HDM) allergens, but little is known whether they harbour cat or dog allergens. The objective of the study was to measure cat (Fel d 1), dog (Can f 1) and HDM allergens on children’s soft toys. Methods: Dust was collected from 40 children’s soft toys and their mattresses. Data were collected on pet ownership. Dust samples were analysed for Fel d 1, Can f 1, Der p 1 and Der f 1 by enzyme-linked immunosorbent assay (ELISA) and results are expressed as median levels with inter-quartile ranges. Results: Thirty-five (87.5%) soft toys had detectable Fel d 1 levels (median: 0.73 µg/g; inter-quartile range: 0.26–2.56 µg/g) while 34 (85%) had detectable Can f 1 levels (1.20 µg/g; 0.53–2.68). Correspondingly, 32 (80%) mattresses had detectable Fel d 1 levels (0.18 µg/g, 0.07–1.01) while 34 (85%) had detectable Can f 1 levels (0.50 µg/g; 0.33–1.06). All mattresses and soft toys had detectable HDM allergen (Der p 1 + Der f 1) levels with soft toys containing about three times higher levels than mattresses. In homes with cats (n = 10) Fel d 1 levels were higher on soft toys than homes without cats (2.49 versus 0.48 µg/g; p = 0.0009). In homes with dogs (n = 25) Can f 1 levels were generally higher on soft toys (1.38 versus 0.63 µg/g; p = 0.10). Conclusions: This study has shown that soft toys can harbour cat and dog allergen as well as HDM allergens, some with very high levels. Cat and dog ownership resulted in higher Fel d 1 and Can f 1 levels on soft toys and mattresses. The levels of Fel d 1, Can f 1 and HDM allergens on soft toys could be of importance to sensitized asthmatic children.

Cat and house dust mite allergen content is stable in frozen mattress dust over time

Background: Dust from indoor environments consists of animal allergens, pollens, endotoxins and other substances which may exacerbate symptoms in sensitive individuals. In prospective cohort studies, dust is often collected from these environments in order to assess allergen exposure and possible relationships to health outcomes. Typically, large numbers of samples are collected and kept frozen until further analysis, which sometimes occurs several years later. To date, there is insufficient knowledge about what happens to the dust and its contents during storage. Aim: In the present study, our aim was to analyse allergen content over a 30 month period in frozen dust collected from beds in homes in order to simulate a study design of exposure assessment commonly used in epidemiological studies. Methods: Thirty-seven dust samples from mattresses in homes were collected using a Duststream dust collector. Each dust sample was distributed into six tubes. Dust from one tube (baseline) was extracted and analysed for cat and HDM allergen content using ELISA, all other tubes were stored at -80°C until further handling. Approximately every six months (6, 12, 18 and 30 months), dust from one tube was thawed, extracted and analysed the same way. Data was log-transformed and analysed using linear regression. Results: No trend for decreasing or increasing cat (p=0.606) or house dust mite (p=0.928) allergen levels in frozen dust could be observed over time. Levels of cat allergen were considerably higher in mattresses from homes with cats compared to homes without cats (p&lt;0.001). Conclusion: It is important to assess the allergen stability in dust before designing costly and labour-intensive studies of allergen exposure and health outcomes, commonly used in environmental epidemiology. Although the present study showed that cat and HDM allergens seem stable in dust stored at -80°C during a 2.5 year period, analyses of other allergens or substances in frozen dust is desirable as well as evaluating the effect of longer storage periods.

Family and home characteristics correlate with mold in homes

Previously, we demonstrated that infants residing in homes with higher Environmental Relative Moldiness Index were at greater risk for developing asthma by age seven. The purpose of this analysis was to identify the family and home characteristics associated with higher moldiness index values in infants’ homes at age one. Univariate linear regression of each characteristic determined that family factors associated with moldiness index were race and income. Home characteristics associated with the moldiness index values were: air conditioning, carpet, age of the home, season of home assessment, and house dust mite allergen. Parental history of asthma, use of dehumidifier, visible mold, dog and cat allergen levels were not associated with moldiness index. Results of multiple linear regression showed that older homes had 2.9 units higher moldiness index (95% confidence interval [CI]=0.4, 5.4), whereas homes with central air conditioning had 2.5 units lower moldiness index (95% CI=−4.7, −0.4). In addition, higher dust mite allergen levels and carpeting were positively and negatively associated with higher moldiness index, respectively. Because older homes and lack of air conditioning were also correlated with race and lower income, whereas carpeting was associated with newer homes, the multivariate analyses suggests that lower overall socioeconomic position is associated with higher moldiness index values. This may lead to increased asthma risk in homes inhabited by susceptible, vulnerable population subgroups. Further, age of the home was a surrogate of income, race and carpeting in our population; thus the use of these factors should carefully be evaluated in future studies.

Evaluation of the level of house dust mite allergens, Der p 1 and Der f 1 in Iranian homes, a nationwide study

BackgroundExposure to house dust mites (HDMs) is a major risk factor for the development of allergic symptoms. HDMs are worldwide in distribution. Assessing these allergens in each area is a critical step in evaluating the risk of sensitisation and controlling allergic symptoms. The aim of the present study was to evaluate the level of major HDMs, Der p 1 and Der f 1, in various parts of Iran. MethodsIn 2009, 257 dust samples were obtained from living rooms’ carpets in seven cities throughout Iran with different geoclimatic conditions. The level of Der p 1 and Der f 1 was measured by commercial ELISA. ResultsDetectable level of Der p 1 and Der f 1 levels were only found in Gorgan and Sari, two cities near the Caspian Sea with moderate temperatures and high relative humidity. In both of these cities, Der f 1 was more frequent than Der p 1 (100% vs. 85%) and was found to be at a higher level than Der p 1 (geometric mean 3128 vs. 439ng/g dust, P<0.001). ConclusionThe results of this study confirm that house dust mites in Iran are restricted to the Caspian Sea coastal areas, and in other parts, due to seasonal variations of temperature and humidity mites are not able to grow well and therefore are not an important risk factor for sensitisation and respiratory allergies.

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.

The Indoor Level of House Dust Mite Allergen Is Associated with Severity of Atopic Dermatitis in Children

We attempted to investigate the correlation between the severity of atopic dermatitis (AD) in children and the indoor level of house dust mite (HDM) allergens. Ninety-five patients (31.1 ± 19.5 months of age) with AD were enrolled in this study, and serum specific IgE against Dermatophagoides pteronyssinus and D. farinae was measured. The severity of AD was assessed using the visual analogue scale on the same day of house dust collection. Living rooms and mattresses where the child usually slept were vacuumed for 2 minutes and concentrations of Der f 1 were measured by enzyme-linked immunosorbent assay. The skin symptoms were more severe in patients with Der f 1 concentrations in living room > 2 µg/g dust than ≤ 2 µg/g dust (P = 0.018). This difference was noted in AD patients without sensitization to HDM (P = 0.004), but not in patients with sensitization. There was no difference in symptom severity according to Der f 1 concentrations in mattresses (P = 0.062). The severity of skin symptoms is associated with indoor concentrations of HDM in children with AD, and it is likely to act as nonspecific irritants as well as allergens in AD skin lesions.