Dust mite allergens: mitigation and control

Spatial distribution of histamine in bed bug-infested homes

Histamine is a component of the bed bug aggregation pheromone. It was recently identified as an environmental contaminant in homes with active bed bug infestations, posing a potential health risk to humans via skin contact or inhalation. It remains unclear how histamine is distributed in homes and if histamine can become airborne. In the present study, histamine levels in household dust were quantified from multiple locations within bed bug infested and uninfested apartments. Bed bug population levels were quantified using both traps and visual counts. The amount of histamine detected varied significantly with respect to sampling location, with the highest concentration of histamine quantified from bedding material. Infestation severity did not have a significant effect on histamine quantified at any location. Our results indicate that the bedroom should be the primary focus of histamine mitigation efforts, although histamine can be found throughout the home. Histamine quantified from homes without active bed bug infestations suggests that histamine from previous infestations can persist following pest eradication. These findings highlight the importance of histamine as a potential insect allergen and will be important for the development of targeted mitigation strategies of bed bug histamine.

Effect of air filtration on house dust mite, cat and dog allergens and particulate matter in homes

Background

Methods

Results

Conclusions

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.

Prevalence of asthma, local risk factors and agreement between written and video questionnaires among Turkish adolescents

BACKGROUND

There is currently no standard tool for the measurement of asthma in epidemiological studies. The objectives of this study were to determine the prevalence of asthma, to describe the potential local risk factors, and to assess the agreement between written and video questionnaires in 13- to 14-year-old schoolchildren.

METHODS

We performed a cross-sectional study involving 5427 adolescents in 26 schools. Prevalence of asthma symptoms were evaluated using the International Study of Asthma and Allergies in Childhood (ISAAC) written and video questionnaire. The adolescents were asked additional questions for risk factors of asthma.

RESULTS

The prevalence of lifetime wheeze, wheeze in the last 12 months and doctor-diagnosed asthma with written questionnaire were found as 13.5%, 6.3% and 11.2% respectively. Prevalence of lifetime wheeze, wheeze in the last 12 months, wheeze after exercise in the last 12 months, with video questionnaire were found as 9.6%, 5.5%, 11.9% and 1.9% respectively. The proportion of total agreement between the two questionnaires was high (0.77-0.81) with poor kappa value (0.25-0.50). In multivariate analysis, family history of atopy, stuffed toys and accompaniment of children to their parents after school hours in textile industry were found as risk factors for asthma. In addition kind of bird, such as canary was found as a risk factor.

CONCLUSION

Prevalence of asthma is moderate in Turkey. Agreement between the two questionnaires was high. Accompaniment of children to their parents in textile industry is a newly-described risk factor for asthma.

Rising trend of allergic rhinitis prevalence among Turkish schoolchildren

OBJECTIVES

To assess the time trends and possible risk factors associated with allergic rhinitis symptoms in schoolchildren from Denizli, Turkey.

METHOD

Two identical cross-sectional surveys were performed in the 13- to 14-yr age group at intervals of six years using ISAAC questionnaire. Possible risk factors were also asked and the children completed questionnaires by self.

RESULTS

A total of 4078 children (response rate 75%) in the 2008 and 3004 children (response rate, 93.8%) in 2002 were included. The lifetime prevalence of rhinitis, 12-month prevalence of rhinitis, prevalence of associated itchy eye in the previous 12 months and doctor diagnosed allergic rhinitis prevalence were increased from 34.2% to 49.4% (POR=1.87, 95% CI=47.8-50.9 and p ≤ 0.001), from 23.5.0% to 32.9% (POR=1.59, 95% CI=31.4-34.3 and p ≤ 0.001), from 9.6% to 14.9% (POR=1.64, 95% CI=13.8-16.0 and p ≤ 0.001), and from 4.3% to 7% (POR=1.67, 95% CI=6.2-7.8 and p ≤ 0.001) respectively. Severe interference with daily activity in the previous 12 months did not change. In multivariate analysis, history of family atopy, stuffed toys, high annual family income, presence of allergy in mother, father and accompaniment of children to their parents after school hours in textile industry were found as risk factors in 2008 study.

CONCLUSION

The prevalence of allergic rhinitis increased significantly in 2008. Family history of atopy, stuffed toys, high annual family income and accompaniment of children to their parents in textile industry were found as risk factors for doctor diagnosed allergic rhinitis.

The Measurement and Health Impact of Endotoxin Contamination in Organic Dusts from Multiple Sources: Focus on the Cotton Industry

Endotoxin is derived from Gram-negative bacterial membranes, and its inflammatory effects following inhalation are well characterized. The significance of this fact becomes apparent when the wide-ranging environments containing high levels of this microbial product are considered. Endotoxin is present in numerous industrial environments, especially where organic fibers are processed. Microbial contamination of these fibers mainly occurs at the agricultural stage. Materials such as flax and hemp are affected in this way, but the most important product in this context is cotton, from which chronic dust inhalation causes the disease byssinosis. Despite the fact that endotoxin constitutes a significant threat to public health, there are currently no occupational exposure limits for this toxicant. This communication describes the toxicology of endotoxin, and its role in inhalation-induced disease, focusing on measurement of airborne endotoxin in the occupational and domestic environments using the Limulus amebocyte lysate (LAL) enzyme assay. Following the success of the LAL assay for measuring endotoxin in dusts, our laboratory has examined its application to aqueous washes from cotton fibers. Reproducibility of the results was high, and data are presented displaying levels of endotoxin contamination in fibers from different cotton producing countries. Hence, worldwide comparison of industrial endotoxin concentrations can be readily made using this test. It would be highly desirable if the performance of the LAL assay facilitated introduction of industrial endotoxin safety limits, and in spite of minor surmountable shortcomings, the test is accurate, reliable, and well field-tested, so its continued widespread use may achieve this goal.

Correlation of environmental mite levels and the symptoms of allergic rhinitis regarding the efficacy of preventive education

Allergic rhinitis is still a commonly investigated disease all over the world. Allergens are usually in the nature of glycoprotein or protein which interact with antibodies resulting in the formation of specific Ig E in the body 1. It is presumed that some environmental factors play an important role in their clinics. In allergic rhinitis, symptoms usually occur after the interaction of nasal mucosa with allergens. Allergens may be indoors, outdoors or in both environments. House-dust contains most of the indoor allergens. Mites are the most egregious allergen in house dust. D. pteronyssinus is commonly seen in European countries, D. farinae is mostly seen in North America. House-dust mites play an important role in allergic sensitization of individuals in Turkey. Perennial allergic rhinitis is a common chronic disorder that results most frequently from sensitivity to house-dust mites. National and international guidelines for the management of allergic rhinitis recommend that house and dust mite avoidance measures be considered for all patients with house-dust mite provoked rhinitis. Symptoms of allergic rhinitis are related to the environmental mite level in which patients live. The aim of this study is to show the relationship between mite levels and symptoms of allergic rhinitis diagnosed patients and the change of mite levels in the environment after appropriate education.

House dust and forage mite allergens and their role in human and canine atopic dermatitis

This article reviews the literature regarding the role of house dust and forage mite allergens in canine atopic dermatitis. The presence of immunoglobulin E (IgE) to these mites, especially to Dermatophagoides farinae, is common in both normal and atopic dogs. Exposure of dogs to the different mites is described both in the direct environment and in the coat of animals for house dust mites and in the food for forage mites. Allergens causing allergic disease in dogs seem to be different from those in humans. Dogs seem to react to high molecular weight allergens, compared to the low molecular weight group 1 and group 2 proteases that are commonly implicated in humans with atopic diseases. Despite numerous published studies dealing with this subject, a number of questions still need to be addressed to better understand the exact role of these mites in the pathogenesis of canine atopic dermatitis and to improve the quality of the allergens used in practice.

Continuous exposure to house dust mite elicits chronic airway inflammation and structural remodeling

It is now fully appreciated that asthma is a disease of a chronic nature resulting from intermittent or continued aeroallergen exposure leading to airway inflammation. To investigate responses to continuous antigen exposure, mice were exposed to either house dust mite extract (HDM) or ovalbumin intranasally for five consecutive days, followed by 2 days of rest, for up to seven consecutive weeks. Continuous exposure to HDM, unlike ovalbumin, elicited severe and persistent eosinophilic airway inflammation. Flow cytometric analysis demonstrated an accumulation of CD4+ lymphocytes in the lung with elevated expression of inducible costimulator a marker of T cell activation, and of T1/ST2, a marker of helper T Type 2 effector cells. We also detected increased and sustained production of helper T cell Type 2-associated cytokines by splenocytes of HDM-exposed mice on in vitro HDM recall. Histologic analysis of the lung showed evidence of airway remodeling in mice exposed to HDM, with goblet cell hyperplasia, collagen deposition, and peribronchial accumulation of contractile tissue. In addition, HDM-exposed mice demonstrated severe airway hyperreactivity to methacholine. Finally, these responses were studied for up to 9 weeks after cessation of HDM exposure. We observed that whereas airway inflammation resolved fully, the remodeling changes did not resolve and airway hyperreactivity resolved only partly.

Synergistic effect of multiple indoor allergen sources on atopic symptoms in primary school children

Accumulating data show that the complex modern indoor environment contributes to increasing prevalence of atopic diseases. However, the dose-response relationship between allergic symptoms and complexity of indoor environmental allergen sources (IEAS) has not been clearly evaluated before. Therefore, we designed this study to investigate the overall effect of multiple IEAS on appearance of asthma (AS), allergic rhinitis (AR), and eczema (EC) symptoms in 1472 primary school children. Among various IEAS analyzed, only stuffed toys, cockroaches, and mold patches fit the model of 'more IEAS, higher odds ratio (OR) of association'. The association of IEAS and AR increased stepwise as more IEAS appeared in the environment (1.71, 2.47, to 2.86). In AS and EC, the association was significant only when all three IEAS were present (1.42, 1.98, to 4.11 in AS; 1.40, 1.76, to 2.95 in EC). These results showed that different IEAS had a synergistic effect on their association with atopic symptoms and also suggest that there is a dose-response relationship between kinds of IEAS and risk of appearance of atopic diseases.