Mite and cat allergen levels in homes and severity of asthma

How Families Manage the Home Environment for Young People With Asthma and Allergic Sensitisation: A Qualitative Study

BACKGROUND AND AIM

Children and young people (CYP) with severe, sub-optimally controlled asthma and co-existing allergic senitization to indoor aeroallergens, such as pet dander and house dust mite (HDM), would likely benefit from reduced allergen exposure. Multiple allergen remediation interventions exist and are often suggested to families in secondary care asthma clinics in the United Kingdom. Evidence suggests remediation uptake is low or partial but there is sparse evidence to explain why. This study aims to explain how families in this situation make decisions about home-based allergen remediations.

METHODS

In-depth qualitative interviews with CYP and mothers were analyzed, and a grounded theory approach was used to develop a theory to explain decision-making processes and behaviors.

RESULTS

Ten CYP aged 11-15 years and 11 mothers were interviewed. The core finding was that families iteratively respond to changes in how certain they are in their asthma management decisions and actions. For allergen remediation uptake, this certainty varied depending on seeing an outcome-exposure relationship, understanding asthma severity, variability, and asthma control at the time of remediation decision-making. Understanding the mechanistic role of allergen exposures in asthma was challenging for families, and ongoing bi-directional communication with clinicians was essential in supporting long-term decision-making.

CONCLUSION

The theory explains the often elongated, reactive process of allergen remediation decision making and implementation. It also explains other elements of family management of asthma, and their interconnections. Families' iterative responsiveness suggests opportunities to intervene and promote earlier, preventative behavior change.

The Impact of the Indoor Environment on Childhood Asthma

PURPOSE OF REVIEW

This manuscript reviews the impact of important indoor environmental exposures on pediatric asthma, with a focus on recent literature in the field.

RECENT FINDINGS

Studies continue to support an association between numerous indoor aeroallergens and air pollutants found in homes and schools and increased asthma morbidity overall. Several recent home and school intervention studies have shown promise, though results have been overall mixed. Indoor environmental exposures contribute to the development of asthma and impact asthma morbidity. Further research is needed to improve our understanding of how to optimize mitigation of these indoor exposures to significantly affect asthma outcomes.

The Prevention of House Dust Mite Allergies in Pediatric Asthma

This review provides a concise overview of preventive measures against dust mite allergies in pediatric populations, emphasizing the need for a comprehensive and evolving approach. Dust mites, ubiquitous microscopic arachnids, pose a significant threat to children's health, triggering allergies and asthma. Traditional preventive strategies such as regular cleaning, mattress covers, and humidity control are essential but warrant refinement. Empowering children through personalized hygiene education and exploring innovative bedding solutions showcase a forward-thinking paradigm. Collaboration with healthcare professionals and embracing technology-driven solutions ensures a holistic and adaptable approach to safeguarding pediatric health against dust mite-related ailments. This abstract underscores the importance of continually reassessing and innovating preventive measures to create resilient and health-conscious living environments for children.

Retrospective Analysis of Allergen Distribution Dynamics in Central Taiwan

Introduction: Allergy is a type Ⅰ hypersensitivity reaction to certain substances (allergens) such as environmental factors, food and drugs. Allergies are a significant public health issue, and therefore, understanding the distribution patterns of allergens in specific regions is important. This study aimed to retrospectively analyse allergen distribution patterns in Central Taiwan over a 5 years period (2018-2022). Methods: Data of patients who had allergen sensitization testing using the OPTIGEN® Allergen-Specific IgE Assay from the 1st of January 2018 to the 31st of December 2022 were reviewed retrospectively. Statistical analyses were performed to determine the prevalence and distribution of allergens in our study population. Results: A total of 8,444 patients (3,784 males and 4,660 females) who attended the Asia University Hospital for allergen detection were enrolled in this study. Dermatophagoides farina (41.8%), Dermatophagoides pteronyssinus (37.9%), house dust (24.6%), cockroach mix (17.7%), crab (12.6%), clam (9.8%), shrimp (9.1%), cat dander (8.1%), pig weed (8%) and peanut (7.8%) were identified as the ten allergens that most commonly induced sensitization in our study population. Additionally, crab, clam, shrimp, peanut and beef were the five most common food allergens. Conclusion: In summary, our findings contribute significantly to the knowledge on allergen distribution in Central Taiwan. Our identification of prevalent allergens may contribute to an improved understanding of the epidemiology of allergies in this region.

Environmental allergen reduction in asthma management: an overview

Asthma is a prevalent non-communicable disease that affects both children and adults. Many patients with severe, uncontrolled asthma could not achieve total control despite using anti-asthmatic drugs. There is increasing evidence that allergy to environmental allergens, including both indoor and outdoor allergens, is associated with asthma symptoms and severe asthma. Frequently reported sensitized allergens were dust mites, cockroaches, grass pollens, molds, pets, and rodents in allergic asthma patients, although the patterns of widespread allergens differed from each country. Allergen avoidance is the cornerstone of asthma management, especially in sensitized subjects. This review summarizes environmental allergen avoidance and clarifies their effects on asthma control. Despite contrasting results about the impact of allergen exposure reduction on asthma control, several studies supported the beneficial effects of reducing asthma-related symptoms or risk of exacerbations as a nondrug therapy. Identifying environmental allergens is helpful for asthma patients, and further studies on clinically effective avoidance methods are required.

Pediatric Inner-City Asthma

Inner-city children with asthma are known to have high disease mortality and morbidity. Frequently, asthma in this high-risk population is difficult to control and more severe in nature. Several factors, including socioeconomic hardship, ability to access to health care, adherence to medication, exposure to certain allergens, pollution, crowd environment, stress, and infections, play an important role in the pathophysiology of inner-city asthma. Comprehensive control of home allergens and exposure to tobacco smoke, the use of immune based therapies, and school-based asthma programs have shown promising results in asthma control in this population.

Update on House Dust Mite Allergen Avoidance Measures for Asthma

PURPOSE OF REVIEW

To critically review the evidence in favor or against the use of house dust mite (HDM) allergen avoidance measures in patients with asthma.

RECENT FINDINGS

Systematic reviews and meta-analyses suggested no positive effect of mite allergen avoidance strategies on asthma outcomes, resulting in a lack of consensus regarding the utility of these measures. However, such analyses have a number limitations and might not be the most adequate tool to evaluate current evidence and to derive clinical recommendations regarding mite allergen avoidance in asthmatic patients. We should not disproportionately rely on the results of meta-analyses and systematic reviews to inform clinical practice and asthma guidelines in this area. Recent high-quality evidence from randomized controlled trial in children confirmed that mite allergen-impermeable bed encasings reduce emergency hospital attendance with acute severe asthma exacerbations. Until better evidence is available, we suggest that physicians should adopt a pragmatic approach to mite allergen avoidance and advise sensitized patients to implement a multifaceted set of measures to achieve as great a reduction in exposure as possible. Potential predictors of positive response (e.g., patient's sensitization and exposure status) can pragmatically be evaluated using the size of skin test wheal or the titer of allergen-specific IgE. Finally, the intervention should be started as early as possible.

The Role of Dust Mites in Allergy

House dust mites are an unsurpassed cause of atopic sensitization and allergic illness throughout the world. The major allergenic dust mites Dermatophagoides pteronyssinus, Dermatophagoides farinae, Euroglyphus maynei, and Blomia tropicalis are eight-legged members of the Arachnid class. Their approximately 3-month lifespan comprises egg, larval, protonymph, tritonymph, and adult stages, with adults, about one fourth to one third of a millimeter in size, being at the threshold of visibility. The geographic and seasonal distributions of dust mites are determined by their need for adequate humidity, while their distribution within substrates is further determined by their avoidance of light. By contacting the epithelium of the eyes, nose, lower airways, skin, and gut, the allergen-containing particles of dust mites can induce sensitization and atopic symptoms in those organs. Various mite allergens, contained primarily in mite fecal particles but also in shed mite exoskeletons and decaying mite body fragments, have properties that include proteolytic activity, homology with the lipopolysaccharide-binding component of Toll-like receptor 4, homology with other invertebrate tropomyosins, and chitin-cleaving and chitin-binding activity. Mite proteases have direct epithelial effects including the breaching of tight junctions and the stimulation of protease-activated receptors, the latter inducing pruritus, epithelial dysfunction, and cytokine release. Other components, including chitin, unmethylated mite and bacterial DNA, and endotoxin, activate pattern recognition receptors of the innate immune system and act as adjuvants promoting sensitization to mite and other allergens. Clinical conditions resulting from mite sensitization and exposure include rhinitis, sinusitis, conjunctivitis, asthma, and atopic dermatitis. Systemic allergy symptoms can also occur from the ingestion of cross-reacting invertebrates, such as shrimp or snail, or from the accidental ingestion of mite-contaminated foods. Beyond their direct importance as a major allergen source, an understanding of dust mites leads to insights into the nature of atopy and of allergic sensitization in general.

Pediatric Inner-City Asthma

Inner-city children with asthma are known to have high disease mortality and morbidity. Frequently, asthma in this high-risk population is difficult to control and more severe in nature. Several factors, including socioeconomic hardship, ability to access to health care, adherence to medication, exposure to certain allergens, pollution, crowd environment, stress, and infections, play an important role in the pathophysiology of inner-city asthma. Comprehensive control of home allergens and exposure to tobacco smoke, the use of immune based therapies, and school-based asthma programs have shown promising results in asthma control in this population.

Update in Pediatric Asthma: Selected Issues

Asthma is a complex condition that affects 14% of the world's children and the approach to management includes both pharmacologic as well as non-pharmacologic strategies including attention to complex socioeconomic status phenomena. After an historical consideration of asthma, allergic and immunologic aspects of asthma in children and adolescents are presented. Concepts of socioeconomic aspects of asthma are considered along with environmental features and complications of asthma disparities. Also reviewed are links of asthma with mental health disorders, sleep disturbances and other comorbidities. A stepwise approach to asthma management is discussed that includes pharmacologic and non-pharmacologic strategies in the pediatric population. The role of immunotherapy and use of various immunomodulators are considered as well.

Inner-City Asthma in Children

Asthma in inner-city children is often severe and difficult to control. Residence in poor and urban areas confers increased asthma morbidity even after adjusting for ethnicity, age, and gender. Higher exposure to household pests, such as cockroaches and mice, pollutants and tobacco smoke exposure, poverty, material hardship, poor-quality housing, differences in health care quality, medication compliance, and heath care access also contribute to increased asthma morbidity in this population. Since 1991, the National Institutes of Allergy and Infectious Diseases established research networks: the National Cooperative Inner-City Asthma Study (NCICAS), the Inner-City Asthma Study (ICAS), and the Inner-City Asthma Consortium (ICAC), to improve care for this at risk population. The most striking finding of the NCICAS is the link between asthma morbidity and the high incidence of allergen sensitization and exposure, particularly cockroach. The follow-up ICAS confirmed that reductions in household cockroach and dust mite were associated with reduction in the inner-city asthma morbidity. The ICAC studies have identified that omalizumab lowered fall inner-city asthma exacerbation rate; however, the relationship between inner-city asthma vs immune system dysfunction, respiratory tract infections, prenatal environment, and inner-city environment is still being investigated. Although challenging, certain interventions for inner-city asthma children have shown promising results. These interventions include family-based interventions such as partnering families with asthma-trained social workers, providing guidelines driven asthma care as well as assured access to controller medication, home-based interventions aim at elimination of indoor allergens and tobacco smoke exposure, school-based asthma programs, and computer/web-based asthma programs.

Indoor mold levels and current asthma among school-aged children in Saskatchewan, Canada

Current knowledge regarding the association between indoor mold exposures and asthma is still limited. The objective of this case-control study was to investigate the relationship between objectively measured indoor mold levels and current asthma among school-aged children. Parents completed a questionnaire survey of health history and home environmental conditions. Asthma cases had a history of doctor-diagnosed asthma or current wheeze without a cold in the past 12 months. Controls were age- and sex-matched to cases. Vacuumed dust samples were collected from the child's indoor play area and mattress. Samples were assessed for mold levels and quantified in colony-forming units (CFU). Sensitization to mold allergens was also determined by skin testing. Being a case was associated with family history of asthma, pet ownership, and mold allergy. Mold levels (CFU/m² ) in the dust samples of children's mattress and play area floors were moderately correlated (r = 0.56; P < 0.05). High mold levels (≥30 000 CFU/m² ) in dust samples from play [adjusted odds ratio (aOR) = 2.6; 95% CI: 1.03-6.43] and mattress (aOR) = 3.0; 95% CI: 1.11-8.00) areas were significantly associated with current asthma. In this study high levels of mold are a risk factor for asthma in children.

House dust-mite allergen exposure is associated with serum specific IgE but not with respiratory outcomes

Exposure to house dust has been associated with asthma in adults, and this is commonly interpreted as a direct immunologic response to dust-mite allergens in those who are IgE sensitized to house dust-mite. Mattress house dust-mite concentrations were measured in a population-based sample of 2890 adults aged between 27 and 56 years living in 22 centers 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. 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. However, there was a positive association of high serum specific IgE levels to HDM (>3.5 kUA /l) with mattress house dust-mite concentrations and a negative association of sensitization to cat with increasing house dust-mite concentrations. In conclusion, there was no evidence that respiratory symptoms in adults were associated with exposure to house dust-mite allergen in the mattress, but an association of house mite with strong sensitization was observed.

Interleukin-13 genetic variants, household carpet use and childhood asthma

Interleukin (IL)-13 genetic polymorphisms have shown adverse effects on respiratory health. However, few studies have explored the interactive effects between IL-13 haplotypes and environmental exposures on childhood asthma. The aims of our study are to evaluate the effects of IL-13 genetic variants on asthma phenotypes, and explore the potential interaction between IL-13 and household environmental exposures among Taiwanese children. We investigated 3,577 children in the Taiwan Children Health Study from 14 Taiwanese communities. Data regarding children's exposure and disease status were obtained from parents using a structured questionnaire. Four SNPs were tagged accounting for 100% of the variations in IL-13. Multiple logistic regression models with false-discovery rate (FDR) adjustments were fitted to estimate the effects of IL-13 variants on asthma phenotypes. SNP rs1800925, SNP rs20541 and SNP rs848 were significantly associated with increased risks on childhood wheeze with FDR of 0.03, 0.04 and 0.04, respectively. Children carrying two copies of h1011 haplotype showed increased susceptibility to wheeze. Compared to those without carpet use and h1011 haplotype, children carrying h1011 haplotype and using carpet at home had significantly synergistic risks of wheeze (OR, 2.5; 95% CI, 1.4–4.4; p for interaction, 0.01) and late-onset asthma (OR, 4.7; 95% CI, 2.0–10.9; p for interaction, 0.02). In conclusions, IL-13 genetic variants showed significant adverse effects on asthma phenotypes among children. The results also suggested that asthma pathogenesis might be mediated by household carpet use.

Endotoxin as a determinant of asthma and wheeze among rural dwelling children and adolescents: a case-control study

BACKGROUND

The association between endotoxin exposure and asthma is complex and has been associated with rural living. We examined the relationship between domestic endotoxin and asthma or wheeze among rural school-aged children (6-18 years) and assessed the interaction between endotoxin and other characteristics with these outcomes.

METHODS

Between 2005 and 2007 we conducted a case-control study of children 6-18 years in the rural region of Humboldt, Canada. Cases (n = 102) reported doctor-diagnosed asthma or wheeze in the past year. Controls (n = 208) were randomly selected from children without asthma or wheeze. Data were collected to ascertain symptoms, asthma history and indoor environmental exposures (questionnaire), endotoxin (dust collection from the play area floor and child's mattress), and tobacco smoke exposure (saliva collection). Statistical testing was completed using multiple logistic regression to account for potential confounders and to assess interaction between risk factors. A stratified analysis was also completed to examine the effect of personal history of allergy.

RESULTS

Among children aged 6-12 years, mattress endotoxin concentration (EU/mg) and load (EU/m2) were inversely associated with being a case [odds ratio (OR) = 0.44, 95% confidence interval (CI) = 0.20-0.98; and OR = 0.38, 95% CI = 0.20-0.75, respectively]. These associations were not observed in older children or with play area endotoxin.

CONCLUSIONS

Our results suggest that endotoxin exposure might be protective for asthma or wheeze. The protective effect is found in younger school-aged, non-allergic children. These results may help explain the inconsistencies in previous studies and suggest that the protective effects of endotoxin in the prevention of atopy and asthma or wheeze are most effective earlier in life.

Association of house dust allergen concentrations with residential conditions in city and in rural houses

BACKGROUND

The aim of the study was to evaluate the relationship between house dust mite, cat and dog allergen levels with household characteristics in the houses of children living in urban and rural areas in central Poland.

METHODS

Dust samples were collected from 141 urban and 191 rural houses. Der f1 + Der p1, Can f 1, and Fel d1 levels were measured and associated with residential conditions and atopy-related health outcomes assessed by clinical examination and skin prick testing.

RESULTS

Concentrations of mite allergens were lower, and cat and dog allergen levels were higher in urban houses. Fel d1 and Can f1 levels depended on the presence of a respective animal in the house. In urban houses, Der p1 + Der f1 concentration was lower in households with central heating, whereas Can f1 concentration was related to building age. Multivariate analyses revealed that the concentrations of house dust mite and dog allergens were associated with relative humidity, number of people in the household, and the presence of a dog at home. There was no significant association between allergen level and sensitization or atopic diseases.

CONCLUSIONS

Concentrations of indoor allergens in urban and rural houses differ significantly, and residential conditions associated with allergen levels seem to be different in both environments.

The association between endotoxin and lung function among children and adolescents living in a rural area

BACKGROUND⁄

OBJECTIVES

Knowledge of the effects of domestic endotoxin on children's lung function is limited. The association between domestic endotoxin and asthma or wheeze and lung function among school-age children (six to 18 years of age) was examined. The interaction between endotoxin and other personal and environmental characteristics and lung function was also assessed.

METHODS

A case-control study was conducted in and around the rural community of Humboldt, Saskatchewan, between 2005 and 2007. Parents of cases reported either doctor-diagnosed asthma or wheeze in the previous year. Controls were randomly selected from those not reporting these conditions. Data were collected by questionnaire to ascertain symptoms and conditions, while spirometry was used to measure lung function including forced vital capacity and forced expiratory volume in 1 s. Dust collected from the child's play area floor and the child's mattress was used to quantify endotoxin, and saliva was collected to quantify cotinine levels and assess tobacco smoke exposure.

RESULTS

There were 102 cases and 207 controls included in the present study. Lower forced expiratory volume in 1 s was associated with higher mattress endotoxin load among female cases (beta=-0.25, SE=0.07 [P<0.01]). There was a trend toward lower forced vital capacity, which was associated with higher play area endotoxin load among cases with high tobacco smoke exposure (beta=-0.17, SE=0.09 [P<0.10]).

CONCLUSIONS

Findings indicated that high endotoxin levels present in common household areas of rural children with asthma or wheeze may also affect their lung function. These associations may be potentiated by tobacco smoke exposure and female sex.

Relationship of endotoxin and tobacco smoke exposure to wheeze and diurnal peak expiratory flow variability in children and adolescents

BACKGROUND AND OBJECTIVE

The relationship between endotoxin exposure and asthma severity (wheeze and airways obstruction) is not well described. The effects of endotoxin and tobacco smoke exposure on self-reported wheeze and diurnal PEF variability (DV-PEF) were examined in children aged 6-18 years with asthma or wheeze.

METHODS

A cross-sectional study was performed in a rural area. From this study, children who reported wheeze in the previous 12 months or a physician diagnosis of asthma (n = 98) were selected for a case-control study. These subjects, who were the basis for the present analysis, completed: (i) a home environmental assessment, including dust collection to measure endotoxin levels: (ii) a clinic visit, including saliva collection to measure cotinine levels; and (iii) 2 week monitoring of twice daily symptom records, including wheeze, and PEF to calculate DV-PEF.

RESULTS

Among these children, 22.4% reported wheeze during the monitoring period. Greater DV-PEF was associated with higher endotoxin loads in play areas (P < 0.05). The association between salivary cotinine levels and high DV-PEF was modified by gender. In females, higher cotinine levels were associated with an increased risk of high DV-PEF compared with lower cotinine levels (P < 0.05), but this was not observed among males.

CONCLUSIONS

Higher endotoxin exposure was associated with greater DV-PEF among children with asthma or wheeze. While previous studies have suggested that endotoxin exposure protects against the development of asthma, individuals with the disease should avoid high exposure levels to limit exacerbations. The effect of tobacco smoke exposure on lung health may differ between male and female children.

Assessment of endotoxin levels in the home and current asthma and wheeze in school-age children

The relationship between household endotoxin and asthma in children is not clear. To further investigate the relationship between sources of endotoxin and childhood asthma, we conducted a case-control study of children with and without asthma and examined their more frequent household exposures in the home. Children ages 6-13 years with current asthma (n = 70) or wheeze only (n = 19) were sex and age matched (+/-1 year) to 107 controls. Play area and mattress dust were collected for endotoxin analysis. Atopic status was determined by skin prick testing for allergies. A family size of >4 per household was associated with higher endotoxin levels (EU/mg) in the bed dust (P < 0.05). Passive smoking (P < 0.05) and the presence of a cat were associated with higher levels of endotoxin in mattress dust. Endotoxin levels in either the play dust or the bed dust did not differ between cases and controls. Within atopic cases, those with higher endotoxin loads (EU/m2) in bed or play areas were more likely to miss school for chest illness (P < 0.05). In this study, household endotoxin is not a risk factor for current asthma overall but may be associated with increased severity in children with atopic asthma.

PRACTICAL IMPLICATIONS

This study did not find that household sources of endotoxin were associated with asthma. However, within atopic asthmatics, asthma severity (as measured by a history of being kept home from school because of a chest illness in the past year) was associated with higher levels of endotoxin in dust from the child's bed. There is a need to further investigate the nature of the relationship between household endotoxin and asthma severity in children which could lead to better management of childhood asthma.

[Environmental factors for asthma severity and allergy: results from the EGEA study]

INTRODUCTION

EGEA (Epidemiological study on the genetics and environment of asthma, bronchial hyperresponsiveness and atopy), a case control and family study including 2048 individuals, was initiated to look for environmental and genetic risk factors for asthma. A synthesis of the results obtained since 2002 on phenotypic and environmental aspects of asthma severity and allergy are presented in this article.

METHODS AND RESULTS

The results support a role for hormonal factors in asthma severity and in various allergic markers of asthma. A greater body mass index was related to a more severe asthma in women with early menarche. Associations between markers of allergy (eosinophils, IgE and atopy) and hormonal dependent events in women (premenstrual asthma, menopause and oral contraceptive use) have been found. In asthmatics, exposure to agents known to be associated with occupational asthma, active and passive smoking were associated with an increased clinical asthma severity score. The study underlines the protective role of country living and exposure to pets in early life on allergy markers in adulthood, supporting the hygiene hypothesis.

CONCLUSIONS

New hypothesis will be tested in the near future from the second stage of this survey.

Lack of association between indoor allergen sensitization and asthma morbidity in inner-city adults

BACKGROUND

Sensitivity and exposure to indoor allergens is associated with increased asthma morbidity in inner-city children. However, it is unknown whether sensitization is associated with worse asthma in adults.

OBJECTIVE

To evaluate the relationship between sensitization and asthma morbidity in urban adults.

METHODS

We prospectively studied 245 adults with persistent asthma recruited from an inner-city clinic. Sensitization to indoor allergens was evaluated by specific IgE antibodies measured at enrollment. Data on asthma control, asthma-related emergency department visits, hospitalizations, and oral steroid use were collected at baseline and at 1-month and 3-month follow-up contacts. Univariate, stratified, and multiple regression analyses were used to compare asthma morbidity in sensitized and nonsensitized patients after controlling for self-reported exposure and other potential confounders.

RESULTS

The study cohort consisted predominantly of low income, minority patients with high rates of resource utilization. The prevalences of sensitization to cockroach, dust mite, cat, mold, and mouse were 60%, 43%, 41%, 21%, and 14%. On univariate analyses, patients sensitized to each allergen did not have worse asthma control or higher resource utilization compared with nonsensitized individuals. Stratified and multivariate analyses also showed no association between sensitization and several measures of asthma morbidity even after controlling for self-reported exposure to indoor allergens and other potential confounders.

CONCLUSION

Sensitization to indoor allergens does not appear to be associated with increased asthma morbidity in inner-city adults.

CLINICAL IMPLICATIONS

These findings suggest that efforts to improve asthma control among urban populations should focus on other modifiable risk factors for morbidity.

A cohort study of indoor nitrogen dioxide and house dust mite exposure in asthmatic children

OBJECTIVE

The purpose of this study was to investigate dose-response relationships between asthma symptoms and indoor nitrogen dioxide (NO2) and house dust mite allergen (HDM) in children.

METHODS

Asthmatic children from 18 primary schools in Adelaide, Australia, kept a daily symptoms diary over 12 weeks. Home and classroom NO2 levels were measured repeatedly in winter 2000. HDM levels were obtained from beds. Lung function tests were performed at the beginning and at the end of the study period.

RESULTS

Data on exposure and respiratory outcomes were gathered for 174 children. For school exposure, the estimated relative symptom rate (RR) for a 10-ppb increase in NO2 for difficulty breathing during the day was 1.09 (95% confidence interval [CI] = 1.03-1.15), at night 1.11 (95% CI = 1.05-1.18), and for chest tightness at night 1.12 (95% CI = 1.07-1.17). Significant symptom rate increases were also found for kitchen NO2 exposure. This was supported by a negative dose-response relationship between percentage predicted forced expiratory volume in 1 second and NO2 (-0.39%; 95% CI = -0.76 to -0.02) for kitchen exposure. Significant threshold effects using a 10-microg/g cutoff point for HDM exposure were established in the sensitized children for nighttime wheeze (RR = 3.62, 95% CI = 1.49-8.77), daytime cough (RR = 1.64, 95% CI = 1.14-2.36), and daytime asthma attack (RR = 1.95, 95% CI = 1.06-3.60).

CONCLUSION

This study has established reliable risk estimates for exacerbations of asthma symptoms in children based on dose-response investigations of indoor NO2 and HDM.

Efficacy and safety of allergen immunotherapy in children

OBJECTIVE

To determine the efficacy and safety of immunotherapy in children with allergic rhinitis and allergic asthma.

DATA SOURCES

Current Contents database for 1967 to 2005.

STUDY SELECTION

The expert opinion of the author was used to select studies for inclusion in this review.

RESULTS

Meta-analyses have confirmed the clinical effectiveness of allergen immunotherapy in patients with allergic rhinitis and asthma; however, most studies involved immunotherapy with a single allergen. Special considerations of safety regarding immunotherapy in children are also necessary, since fatalities have been reported. Fatal reactions occur primarily in patients with asthma and particularly those whose asthma is not well controlled. There is probably increased risk during the build-up phase and with the first injection from a new vial. Injections at home or in clinics without adequate supervision also constitute an increased risk of a fatal outcome.

CONCLUSIONS

Specific immunotherapy has been demonstrated to have some protective effect against the development of additional sensitivities in the monosensitized child and to reduce the risk of developing asthma in children with allergic rhinitis. Because of the modification of the underlying immune process, the beneficial effects of immunotherapy persist for a long but not yet fully determined period after the cessation of treatment. This persisting effect makes immunotherapy an attractive supplement to symptomatic treatment of children with allergic asthma and allergic rhinitis. The treatment is not without risk, however, especially in the child with asthma, so it should be administered with caution.

Infant sleeping environment and asthma at 7 years: a prospective cohort study

OBJECTIVES

We investigated the role of infant bedding items, as part of a composite bedding environment, in the development of childhood wheezing.

METHODS

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.

RESULTS

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.

CONCLUSIONS

Our results show that bedding exposures in infancy are prospectively associated with childhood wheezing and that home environmental conditions may modify this association.

Possible reasons for lack of effect of allergen avoidance in atopy-prone infants and sensitive asthmatic patients

The basic paradigm that allergen exposure produces atopic sensitization, and that continued exposure leads to clinical asthma throughout the development of airway inflammation and bronchial hyperreactivity has been challenged. However, because it was observed that epidemiological evidence suggests that around 40% of asthma cases are attributable to atopy (even using restrictive criteria), the obvious corollary is that if allergen avoidance begins before the onset of sensitization (primary prevention), then it should be associated with a reduced number of new cases of the disease. However, there are conflicting results regarding the effect of allergen avoidance on primary prevention of atopic sensitization and asthma onset. Instead, more uniform and positive results are available from secondary prevention studies. Secondary prevention obviously is an attractive opportunity for pediatricians who may recognize the patients who might benefit from these interventions simply by screening for food allergy in young children with atopic dermatitis. The conflicting results of tertiary prevention are most frequently observed in adult patients and sometimes result from incomplete avoidance of allergens responsible for the sensitization.

High allergen exposure as a risk factor for asthma and allergic disease

The association between pet ownership in childhood and subsequent asthma and sensitization is very controversial. Intriguing, but contradictory, reports have caused considerable uncertainty in parents who wish to avoid asthma and allergic disease in their children. This article argues that high allergen exposure is a risk factor for asthma and allergic disease. It describes dispersal of pet allergens in society and critically assesses epidemiological studies regarding how early exposure to pet allergens affects subsequent immunoglobulin E-sensitization and allergic diseases. Additionally, this article evaluates the effects of allergen exposure in already sensitized subjects with asthma. Cat and dog allergens are ubiquitous in society and may induce sensitization and allergic symptoms in predisposed individuals, regardless of pet ownership. This, in combination with selection mechanisms for pet ownership in families with a history of allergic diseases, makes it difficult to study associations between early exposure to pets and subsequent allergic disease. Nevertheless, exposure to pet allergens worsens asthma in already sensitized children. Thus, it is clear that clinicians should advise sensitized asthmatics that avoidance of exposure to indoor allergens is an important element in the treatment of allergic disease.

Impact of the home indoor environment on adult asthma and rhinitis

OBJECTIVE

We sought to study the combined effects of multiple home indoor environmental exposures in adult asthma and rhinitis.

METHODS

We studied 226 adults with asthma and rhinitis by structured interviews and home assessments. Environmental factors included dust allergen, endotoxin and glucan concentrations, and indoor air quality (IAQ) variables. Outcomes included forced expiratory volume in 1 second (FEV1) percent predicted, Severity of Asthma Score (SAS), Short-Form (SF)-12 Physical Component Scale (PCS), and asthma Quality of Life (QOL) score.

RESULTS

House dust-associated exposures together with limited IAQ variables were related to FEV1 % predicted (R = 0.24; P = 0.0001) and SAS (R = 0.18; P = 0.007). IAQ and limited dust variables were associated with SF-12 PCS (R = 0.15; P = 0.02), but not QOL (R = 0.13; P = 0.16).

CONCLUSIONS

The home environment is strongly linked to lung function, health status, and disease severity in adult asthma and rhinitis.

Predictors of disease severity in children with asthma in Hartford, Connecticut

Childhood asthma is a major public health problem in the United States, particularly among minority populations. The aim of our study was to examine the relationship among ethnicity, allergen sensitization, spirometric measures, and asthma severity in children with mild to severe asthma who received their medical care in Hartford, Connecticut. Four hundred thirty-eight children aged 4-18 years who were enrolled in an asthma care program (Easy Breathing) in Hartford and who were referred for spirometry and allergy skin testing participated in this cross-sectional study. Risk factors for increased asthma severity as defined by National Asthma Education and Prevention Program (NAEPP) guidelines were determined using multinomial logistic regression. Of 438 children, 383 (87.4%) had mild to moderate asthma, and 292 (66.7%) had at least one positive skin test to allergens. Forced expiratory volume in 1 sec/forced vital capacity (FEV1/FVC) was significantly decreased in children with severe vs. mild asthma (80.7 vs. 87.3, respectively). In a multivariate analysis, predictors of severe asthma included African-American ethnicity (odds ratio (OR)=3.70, 95% confidence interval (CI)=1.10-12.42), Puerto Rican ethnicity (OR=3.55, 95% CI=1.18-10.67), sensitization to cockroach allergen (OR=4.34, 95% CI=1.73-10.86), and decreased FEV1/FVC (OR for every 1% decrease in FEV1/FVC=1.06, 95% CI=1.02-1.11). In conclusion, among children with asthma in Hartford and its surrounding communities, predictors of disease severity included African-American ethnicity, Puerto Rican ethnicity, sensitization to cockroach allergen, and decreased FEV1/FVC. Our findings suggest that FEV1/FVC is a useful indicator of asthma severity in children.

[Multidimensional character of asthma severity in the EGEA study]

RATIONALE

The severity of asthma has been defined by various criteria in epidemiology, but their relationships have been rarely studied.

MATERIAL AND METHODS

The interrelationships between various asthma severity criteria (clinical severity in the past 12 months) (score 0-7), functional (FEV1), therapy (inhaled steroids used in the past 12 months) and hospitalization during life were studied. Bivariate (OR) and multivariate (factorial analyses, log-linear models) analyses were applied in asthmatic children (n=135) and adults (n=213) recruited in chest clinics for the EGEA study (Epidemiological Study on the Genetics and Environment of Asthma).

RESULTS

In asthmatics, the proportion of severe asthma was highly dependent on the definition used. Whatever the statistical method used, FEV1 in children was unrelated to treatment, hospitalization and the clinical score. In adults, the clinical score was not associated with hospitalization, treatment and FEV1, these last three criteria being highly related to each other.

CONCLUSION

Results support the hypothesis of the multidimensional character of severity of asthma.

Presence and timing of cat ownership by age 18 and the effect on atopy and asthma at age 28

BACKGROUND

Asthma and allergic sensitization to cats frequently coexist, although recent studies show less atopic disease among people who had pets in infancy. However, no longterm evaluations have been performed thus far.

OBJECTIVE

We sought to evaluate the relationship between cat ownership at different age periods (< 18, > 18, and both periods and atopic disease at age 28.

METHODS

Australian school children aged 8 to 10 years were recruited in 1982 and participated in follow-up surveys until 2002. Cat ownership was defined by surveys in 1992 and 2002 as having a cat before age 18 only, after age 18 only, or in both periods of life. Health outcomes were defined at a mean age of 28.5 years.

RESULTS

Complete data were available for 224 subjects, 50 of whom had a cat before 18 years of age only, 14 after age 18 only, and 70 in both periods. Compared with 90 subjects that never had a cat, having a cat before age 18 protected against atopy to outdoor allergens, airway hyperresponsiveness (AHR) to histamine, current wheeze, and current asthma (P < .05). In contrast, subjects who acquired their first cat after age 18 showed a trend toward higher prevalence rates for asthma symptoms and AHR (P > .10).

CONCLUSIONS

Having had a cat before 18 years of age protects against adult asthma and atopy.

The bedding environment, sleep position, and frequent wheeze in childhood

OBJECTIVE

Synthetic quilt use has been associated with increased childhood wheeze in previous studies. Our aim was to examine whether the adverse effect of synthetic quilt use on frequent wheeze differed by usual sleep position.

DESIGN, SETTING, AND PARTICIPANTS

A population-based cross-sectional study of 6378 (92% of those eligible) 7-year-olds in Tasmania, Australia, was conducted in 1995. Exercise-challenge lung function was obtained on a subset of 414 children from randomly selected schools.

EXPOSURE MEASURES

Child bedding including pillow and overbedding composition and usual sleep position by parental questionnaire.

OUTCOME MEASURES

Frequent wheeze (>12 wheeze episodes over the past year), using the International Study of Asthma and Allergies in Childhood parental questionnaire, and baseline and postexercise forced expiratory volume in 1 second lung-function measures.

RESULTS

Frequent wheeze (n = 117) was positively associated with synthetic quilts, synthetic pillows, electric blankets, and sleeping in a bottom bunk bed but did not vary by sleep position. In a nested case-control analysis, the association between synthetic quilt use and frequent wheeze differed by sleep position. Among children who slept supine, synthetic (versus feather) quilt use was associated with frequent wheeze (adjusted odds ratio: 2.37 [1.08, 5.23]). However, among nonsupine sleepers, overlying synthetic quilt use was not associated with frequent wheeze (adjusted odds ratio: 1.06 [0.60, 1.88]). This difference in quilt effect by sleep position was highly significant. Similarly, synthetic quilt use was associated with lower postexercise forced expiratory volume in 1 second measures among supine but not nonsupine sleeping children.

CONCLUSION

An increasing focus on the bedding environment immediately adjacent to the nose and mouth is required for respiratory disorders provoked by bedding, such as child asthma characterized by frequent wheeze.

The Canadian asthma primary prevention study: outcomes at 2 years of age

BACKGROUND

Avoidance of individual risk factors have not been successful in preventing the development of asthma.

OBJECTIVE

We sought to determine the effectiveness of a multifaceted intervention program in primary prevention of asthma in high-risk infants.

METHODS

We identified 545 high-risk infants on the basis of an immediate family history of asthma. Families were randomized into intervention or control groups. Intervention measures included avoidance of house dust mite, pet allergen, and environmental tobacco smoke. Breast-feeding was encouraged with formula supplementation if necessary, and introduction of solid foods was delayed.

RESULTS

At 2 years of age, 19.5% of the children had asthma, and 14.7% had atopy (positive skin test response to one or more common allergens). Significantly fewer children had asthma in the intervention group compared with in the control group (16.3% vs 23.0%), with 60% less persistent asthma at 2 years. There was a 90% reduction for recurrent wheeze in the intervention group compared with that seen in the control group. Exposure to maternal environmental tobacco smoke during pregnancy or the first year was a risk factor for asthma at 2 years of age. A positive skin test response, particularly to food, at 12 months predicted asthma at 2 years. There was no significant difference for atopy between the intervention and control groups, but daycare reduced atopy at 2 years.

CONCLUSION

This multifaceted intervention program during a window of opportunity in the first year of life was effective in preventing asthma in high-risk children at 2 years of age. Future studies with this cohort at school age are important.

[An increase in allergic diseases in childhood--current hypotheses and possible prevention]

During the last few decades there has ben a significant rise in the prevalence of allergic diseases such as asthma, hay fever and atopic dermatitis. Epidemiological studies strongly suggest that this increase is real and not due to changes in diagnostic labelling. It has become increasingly clear that a complex interplay between genetic and environmental factors account for this phenomenon. Genetically predisposed individuals are at an increased susceptibility to develop asthma or other allergic diseases when exposed to certain environmental or lifestyle factors. Particularly passive smoking has been shown to increase the risk for asthma in many studies and for atopy at least in some studies. This association is less clear for the exposure to sulfur dioxide, particulate matter, diesel exhaust and ozone. Lifestyle factors like socioeconomic status, sib-ship size, early childhood infections, dietary habits, growing up in antroposophic families or on a farm are more and more realised to be of great relevance for the development of allergic conditions. At the moment, there is a lot of uncertainty about which recommendations should be given for primary prevention. Recent studies have challenged the old paradigma that avoidance of early allergen contact could prevent the development of allergic disease. However, there is consensus that avoidance of smoking during pregnancy and avoidance of passive smoking during childhood should be recommended for primary prevention of asthma.

Relationships of allergic sensitization, total immunoglobulin E and blood eosinophils to asthma severity in children of the EGEA Study

BACKGROUND

Although allergy is highly associated with childhood asthma, it is not well known if there is a relationship between the intensity of allergic sensitization and asthma severity.

OBJECTIVE

The objectives of the study were to examine the relationships between several markers of allergy and asthma severity in asthmatic children included in the Epidemiological study on the Genetics and Environment of Asthma, bronchial hyper-responsiveness and atopy (EGEA).

METHODS

The population comprised 216 asthmatic children below 16 years of age. Total IgE and blood eosinophil counts were measured and skin prick tests to 11 aeroallergens were performed. The intensity of the allergic sensitization was assessed by the number of positive skin prick tests and by skin weal sizes. Asthma severity was measured with four criteria: a clinical severity score, history of hospitalization for asthma, FEV1% predicted and inhaled steroid use in the last 12 months.

RESULTS

Most of the children were sensitized to at least one aeroallergen (88.2%). Atopy was not related to the severity of asthma, except for a tendency for a more severe clinical score in non-atopic children. The type and intensity of the allergic sensitization were not associated with any criteria of asthma severity. Total IgE was significantly increased in children treated with inhaled corticosteroids and in children ever hospitalized for asthma (P-values 0.009 and 0.04, respectively). Eosinophil counts were not related to asthma severity.

CONCLUSION

Our results suggest that severe childhood asthma may be related to a high level of total IgE but not to blood eosinophil counts. The lack of positive relationships between both atopy and the intensity of allergic sensitization with asthma severity supports the hypothesis of different risk factors being associated with asthma and with the severity of asthma.

Synthetic bedding and wheeze in childhood

BACKGROUND

The reasons for the increase in childhood asthma over time are unclear. The indoor environment is of particular concern. An adverse role for synthetic bedding on asthma development in childhood has been suggested by cross-sectional studies that have found an association between synthetic pillow use and childhood wheeze. Prospective data on infant bedding have not been available.

METHODS

Bedding data at 1 month of age were available from an infant survey for children who were participating in a 1995 follow-up study (N = 863; 78% traced). The 1995 follow-up was embedded in a larger cross-sectional survey involving 6,378 seven year olds in Tasmania (N = 92% of eligible). Outcome measures included respiratory symptoms as defined in the International Study of Asthma and Allergies in Childhood protocol. Frequent wheeze was defined as more than 12 wheeze episodes over the past year compared with no wheeze.

RESULTS

Synthetic pillow use at 1 month of age was associated with frequent wheeze at age 7 (adjusted relative risk [aRR] = 2.5; 95% confidence interval [CI] = 1.2-5.5) independent of childhood exposure. Current synthetic pillow and quilt use was strongly associated with frequent wheeze (aRR = 5.2; CI = 1.3-20.6). Substantial trends were evident for an association of increasing number of synthetic bedding items with frequent wheeze and with increasing wheeze frequency. Among children with asthma, the age of onset of asthma occurred earlier if synthetic bedding was used in infancy.

CONCLUSIONS

In this cohort, synthetic bedding was strongly and consistently associated with frequent childhood wheeze. The association did not appear to be attributable to bedding choice as part of an asthma management strategy.

Cord blood mononuclear cell cytokine responses in relation to maternal house dust mite allergen exposure

BACKGROUND

Cord blood mononuclear cells have demonstrated specific immune responses to environmental allergens.

OBJECTIVE

To establish whether the nature of this response is related to the level of maternal antenatal exposure to house dust mite (HDM) allergen and, hence, whether antenatal allergen avoidance may have a role in the prevention of allergic sensitization in children.

METHODS

Children with a family history of asthma were recruited antenatally as subjects in a randomised controlled trial: the Childhood Asthma Prevention Study. HDM allergen (Der p 1) concentrations were measured in dust collected from the maternal bed at 36 weeks gestation. Cord blood mononuclear cells were stimulated in culture, separately, with phytohaemaglutinin (PHA) and HDM extract. Cytokine IL-4, IL-5, IL-10 and IFN-gamma concentrations in supernatant were measured by ELISA. mRNA signals for these cytokines were measured using RT-PCR.

RESULTS

The median concentration of HDM allergen was 18.4 microg/g (interquartile range 7.3-35.3 microg/g). Median concentrations of IL-4, IL-5, IL-10 and IFN-gamma, after PHA stimulation were 4, 19, 401 and 1781 pg/mL, respectively. After HDM allergen stimulation the median concentrations were 0, 0, 20 and 14 pg/mL, respectively. The distribution of mRNA cytokine signals was similar. Neither cytokine protein concentrations nor cytokine mRNA signal levels were correlated with the concentration of HDM allergen in the mothers' beds at 36 weeks gestation.

CONCLUSION

These findings do not support the view that the prevention of allergic disease in children requires the institution of HDM avoidance interventions during pregnancy.

Predictors of high house dust mite allergen concentrations in residential homes in Sydney

BACKGROUND

In parts of coastal Australia, house dust mite allergen concentrations in homes are often very high with at least 80% of homes in Sydney exceeding concentrations of 10 microg of allergen per gram of fine dust. In this study, we report the relation between characteristics of the home environment and house dust mite allergen concentrations at three sites in Sydney homes.

METHODS

A total of 616 families were recruited as part of the Childhood Asthma Prevention Study (CAPS). Information about the home environment and structural aspects of the home was collected using a questionnaire. Samples of dust were collected from the parents' bed, the bedroom floor and the living room floor and assayed for Der p 1.

RESULTS

A total of 68% of participants' beds, 65% of bedroom floors and 56% of living room floors had Der p 1 concentrations above 10 microg/g, with the highest concentrations of allergen in the bed. The most significant predictor of high Der p 1 concentrations in the bed and floors was the age of the home. We also found that beds with mattresses over two years old and with woollen or synthetic blankets or synthetic quilts had higher Der p 1 concentrations. Carpeted floors had higher Der p 1 concentrations than hard floors.

CONCLUSION

The finding that high Der p 1 allergen concentrations in homes with carpets and older mattresses indicates that control strategies directed at these sources are likely to be effective in reducing exposure. Alternatives such as the use of house dust mite impermeable mattress encasings on older mattresses may also be effective in reducing exposure.

Primary prevention of asthma

There has been a dramatic increase in the prevalence of asthma over the last quarter century, particularly in the industrialized world. Although our understanding of asthma continues to improve, there is no cure for the disease. Primary prevention of asthma is the focus of this review. Asthma is a disease with multiple gene-environment interactions. Candidate genes for asthma are considered, and potential interaction between one of those genes, CD14, and an environmental factor, endotoxin, is reviewed as it relates to the hygiene hypothesis. Environmental risk factors for asthma including allergens, pollutants, infectious factors, and dietary modifications are considered, particularly their potential for primary prevention of asthma. Ongoing cohort studies including the Canadian Allergy and Asthma Prevention Study, the Manchester Allergy and Asthma Study, the Children's Asthma Prevention Study from Australia, and the Prevention and Incidence of Asthma and Mite Allergy Study from the Netherlands are briefly reviewed. A more definitive understanding of genetic background and environmental triggers and their interactions is required before any specific approach to the primary prevention of asthma can be championed aggressively.

Effectiveness of and compliance to intervention measures in reducing house dust and cat allergen levels

BACKGROUND

Allergic sensitization is a major risk factor in asthma.

OBJECTIVE

To evaluate the effectiveness of and compliance to intervention measures in reducing levels of house-dust mite and cat allergen in the context of a randomized, controlled study in the primary prevention of asthma.

METHODS

A total of 545 high-risk families were recruited prenatally and randomly assigned into the intervention group (n = 278) and the control group (n = 267). Intervention measures were instituted before birth of the infants and maintained for 12 months afterward in the intervention group and the control group received the usual care from their family physician. Dust samples were collected at six sites in the homes before birth and at specific intervals up to 24 months after birth for analysis of allergens. At 24 months, there were 244 families in the intervention group and 228 in the control group available for followup examination.

RESULTS

House-dust mite avoidance measures, consisting of encasement of mattresses, pillows, and duvets, and hot-water washing of bedding were effective in reducing mite allergen in parents' mattresses to one-third from baseline, significantly lower than the control group, even at 24 months. The use of an acaricide did not reduce mite allergen levels in carpets and upholstered furniture. Seventeen intervention families gave up their cats but six families acquired a new one over a period of 24 months, similar to control families. Cat allergen levels decreased in all sites in the homes of those who removed the cat, similar in both groups.

CONCLUSIONS

House-dust mite avoidance measures were effective in reducing house-dust mite allergen in mattresses, but not on floors. Reduction in cat allergen levels were evident for those families who got rid of their cats, but the advice to remove pets was not adhered to by most families.

A polymorphism in the coding region of interleukin-13 gene is associated with atopy but not asthma in Chinese children

BACKGROUND

Interleukin (IL)-13 is an important cytokine secreted from type 2 helper T lymphocytes. It is essential for modulating IgE synthesis by human B cells. Previous studies showed that polymorphisms in the IL-13 gene were associated with serum total IgE or allergic asthma. The relationship of this marker with sensitization to individual aeroallergens has not been evaluated.

OBJECTIVE

We tested whether a polymorphism in the coding region of the IL-13 gene is associated with asthma and atopy in asthmatic children in Hong Kong.

METHODS

We used restriction fragment length polymorphism to detect R130Q genotype in Chinese children with asthma and control subjects. Serum total IgE was measured by microparticle immunoassay and specific IgE to common aeroallergens was measured using fluorescent enzyme immunoassay. Pulmonary function studies were performed using spirometry.

RESULTS

One hundred and fifty-seven patients and 54 control children were recruited. Their mean serum total IgE concentrations were 994 kIU/L and 473 kIU/L, respectively (P < 0.0001). Atopy as defined by > or = 1 positive RAST was found in 141 patients and 32 control children. The GlnGln form of the R130Q polymorphism in the IL-13 gene was associated with serum total IgE (P = 0.005) as well as specific IgE to Der p 1 (P = 0.021), mixed cockroaches (P = 0.03) and dog (P = 0.003) but not with physician-diagnosed asthma (P = 0.621). In addition, the R130Q polymorphism did not correlate with subjective or objective indicators of asthma severity in our patients.

CONCLUSION

Our results suggest that the R130Q polymorphism of the IL-13 gene is associated with elevated serum total and allergen-specific IgE but not asthma in Chinese children.

Respiratory symptoms in relation to indoor exposure to mite and cat allergens and endotoxins. Indoor Factors and Genetics in Asthma (INGA) Study Group

The authors investigated the relationship between respiratory symptoms in adults and exposure to mite and cat allergens, the role of endotoxins in house dust, the effects of mixtures of several allergens, and interactions between allergen exposure and allergic sensitization. Within a nested case-control study, 405 subjects aged 25-50 yrs from two German cities answered a standardized questionnaire. Allergen-specific immunoglobulin-E was measured. Dust samples were taken from the subjects' homes to determine exposure to mite (Dermatophagoides pteronyssinus antigen 1 Der p 1) and (D. farinae antigen 1 Der f l) and cat (cat antigen d1 Fel d 1) allergen and endotoxin content in settled house dust. Exposure to Der f 1 and Der p 1 plus Der f 1 >10 microg x g(-1) of mattress dust, respectively, increased the risk of wheeze and breathlessness (odds ratios (OR): 4.04, 95% confidence interval (CI): 1.53-10.64, OR: 2.78, 95% CI: 1.06-7.28). Fel d 1 >8 microg x g(-1) was positively associated with cough at night (OR: 2.74, 95%, CI: 1.22-.17), noteworthy also in the nonsensitized subjects. Subjects exposed to elevated concentrations of more than one allergen had an up to seven-fold increase in the risk of respiratory symptoms, compared to nonexposed subjects. Sensitized subjects exposed to elevated concentrations of Der f 1 or Fel d 1 were found to have the highest risk of asthma attacks and respiratory symptoms. No statistically significant association was found between exposure to endotoxins and respiratory health. Indoor exposure to Dermatophagoides farinae antigen 1 and cat antigen d1 is a risk factor for respiratory symptoms in adults, and for cat antigen d 1 even in nonsensitized subjects. The risk is increased if subjects are exposed to a mixture of allergens or if they are sensitized in addition to high exposure.

Asthma severity, atopic status, allergen exposure and quality of life in elderly persons

BACKGROUND

Although asthma can be associated with significant airflow obstruction in those over the age of 65, it is often underdiagnosed and undertreated.

OBJECTIVE

To describe severity of asthma, allergy skin test sensitivities, indoor allergen exposures, and the impact on quality of life (QOL) and health status in elderly persons with asthma.

METHODS

A cross-sectional data analysis with 80 elderly persons with asthma recruited from medical, geriatric, and allergy/immunology tertiary care centers. Asthma severity was determined by symptoms and measurements of lung function. House dust specimens were collected from mattresses and bedroom carpets and analyzed separately for the major allergens of house dust, using monoclonal antibody-based immunoenzymetric assays. QOL was measured using Juniper's Asthma Quality of Life Questionnaire. Health status was measured using the Short Form Health Survey Medical Outcome Questionnaire which included Ferrans and Powers' Quality of Life Index subscales.

RESULTS

Two-thirds of participants had either moderate or severe persistent asthma. Skin tests to a battery of common airborne allergens were positive to at least one allergen in 56 of the 75 participants tested (74.7%). Reservoir dust allergen levels were often high enough to place participants at risk of symptoms or at risk of developing sensitization. Increased asthma severity was associated with significantly lower QOL and a trend toward decreased health status.

CONCLUSIONS

Asthma is a significant chronic problem in the elderly. Atopy was common. Asthma severity impacts on these participants' QOL and health status. Results support interventions aimed at identifying allergens precipitating attacks and reducing them in the home.

The importance of allergens in the development of asthma and the persistence of symptoms

The importance of allergies and allergens in the development and persistence of asthma is suggested by 3 lines of evidence. First, a number of epidemiologic studies demonstrate that sensitization to indoor allergens and the spores of the outdoor seasonal fungus Alternaria is a risk factor for the development of asthma in both children and adults. Sensitivity to pollens, on the other hand, rarely constitutes a risk for asthma but does constitute a risk for seasonal allergic rhinitis. Second, several studies, again in both children and adults, have demonstrated that, in persons sensitive to indoor allergens, the severity of asthma symptoms will vary with the level of exposure. Third, the elimination of exposure to house-dust mites has produced a remarkable reversal of asthma in sensitive children and adults. Not only have symptoms and pulmonary function improved, but there has also been evidence of a reduction in airway inflammation and hyperresponsiveness. Taken together, these studies make a strong argument for the importance of allergy and allergen exposure as aggravating factors in asthma in both children and adults and reinforce the importance of the identification and treatment of these allergen sensitivities. (J Allergy Clin Immunol 2000;105:S628-32.)

Suspended particulate matter in indoor air: adjuvants and allergen carriers

The overall purpose of this study was to investigate how airborne house dust particles may contribute to an allergic immune response, and thereby also to asthma and other respiratory symptoms. The following aims were set: first, to quantify and characterize indoor suspended particulate matter (SPM) with regard to amount, as well as elemental and size distribution, second, to identify possible mechanisms by which SPM may affect the allergic immune response. A vast majority of the particles in SPM samples from homes in Oslo were found to be less than 2.5 microm in diameter. This PM(2.5) fraction contained, in addition to a large amount of sulfur aerosols and silicates, a lot of soot particles. Most of these were less than 1 microm in diameter. Using an immunogold labeling technique, we found that these soot particles carried cat, dog and birch allergens on their surface. These results show that indoor SPM contains a lot of potential allergen carriers, i.e. soot particles (carbon aggregates), most of them less that 1 microm in diameter and therefore able to transport allergens deep into the respiratory tree. We further found that diesel exhaust particles (DEP), which is likely the main soot component of SPM, adsorbed several well-known allergens in vitro. Furthermore, SPM was found to elicit a local lymph node inflammatory response, and to have an adjuvant activity on the production of IgE antibodies to ovalbumin (OA).

Pets and cockroaches: two increasing causes of respiratory allergy in indoor environments. Characteristics of airways sensitization and prevention strategies

The increasing prevalence of allergic sensitization to indoor allergens such as dust mites, pets and cockroaches is the result of the changes in indoor environments induced by human activities. The Westernized lifestyle and the increasing time spent indoors determine a reduction in natural air ventilation and, consequently, higher levels of allergen concentrations and longer exposure to allergens. The major cat allergen Fel d 1 is carried by small-dimension particles (< 5 microm diameter) that readily become airborne and persist immodified for a long time. Fel d 1 must be considered a ubiquitous allergen because it has been found in indoor environments and even in public places where a cat has never been kept. Recent research has demonstrated that clothing of cat owners may contribute to the dispersal of Fel d 1 in cat-free environments. Therefore, washing Fel d 1-contaminated clothes should be considered a simple and effective method for removing this allergen from clothing and, consequently, reducing the risk of Fel d 1 dispersion. Cockroach allergens constitute another important cause of environment-related respiratory allergy and may trigger asthma exacerbations in sensitized individuals. In the prevention of cockroach allergy, the use of chemical agents associated with an intensive vacuum cleaning of indoor environments is an important tool in removing cockroach material containing allergenic proteins. Early recognition of allergy-predisposed babies, monitoring indoor allergens and adequate strategies of allergen avoidance are likely to be important means for reducing the prevalence of bronchial asthma.

Persistent asthma: patient characteristics, courses of asthma, and utility of salmeterol

Applications of National Asthma and Education and Prevention Program (NAEPP) guidelines for the diagnosis and management of asthma may reduce the morbidity of this disorder. Medical records and questionnaires from a series of 177 outer-city adolescents and adults with persistent asthma were audited according to NAEPP guidelines and for utility of salmeterol (Serevent). Allergic sensitivity and exposure to indoor allergens house-dust mite (66% of patients), fungi (42%), cat (20%) and/or dog (14%) were of dominant importance to persistent asthma. Patients who continued salmeterol over 1 year had reduced severity of disease, improved forced expiratory flow at 25%-75% of vital capacity, and reduced usage of systemic, but not inhaled, corticosteroid.