Cockroach allergen (Bla g 1) in school dust

Social determinants of health and asthma

PURPOSE OF REVIEW

Social determinants of health play a major role in healthcare utilization and outcomes in patients with asthma. Continuing to understand how these complex and interwoven relationships interact to impact patient care will be crucial to creating innovative programmes that address these disparities.

RECENT FINDINGS

The current literature continues to support the association of substandard housing, urban and rural neighbourhoods, and race/ethnicity with poor asthma outcomes. Targeted interventions with community health workers (CHWs), telemedicine and local environmental rectifications can help improve outcomes.

SUMMARY

The link between social determinants and poor asthma outcomes continues to be supported by recent literature. These factors are both nonmodifiable and consequences of institutionalized racist policies that require innovative ideas, technologic equity and funding for groups most at risk for poorer outcomes.

Environmental justice and allergic disease: A Work Group Report of the AAAAI Environmental Exposure and Respiratory Health Committee and the Diversity, Equity and Inclusion Committee

Environmental justice is the concept that all people have the right to live in a healthy environment, to be protected against environmental hazards, and to participate in decisions affecting their communities. Communities of color and low-income populations live, work, and play in environments with disproportionate exposure to hazards associated with allergic disease. This unequal distribution of hazards has contributed to health disparities and is largely the result of systemic racism that promotes segregation of neighborhoods, disinvestment in predominantly racial/ethnic minority neighborhoods, and discriminatory housing, employment, and lending practices. The AAAAI Environmental Exposure and Respiratory Health Committee and Diversity, Equity and Inclusion Committee jointly developed this report to improve allergy/immunology specialists' awareness of environmental injustice, its roots in systemic racism, and its impact on health disparities in allergic disease. We present evidence supporting the relationship between exposure to environmental hazards, particularly at the neighborhood level, and the disproportionately high incidence and poor outcomes from allergic diseases in marginalized populations. Achieving environmental justice requires investment in at-risk communities to increase access to safe housing, clean air and water, employment opportunities, education, nutrition, and health care. Through policies that promote environmental justice, we can achieve greater health equity in allergic disease.

Asthma and Allergies in the School Environment

The school is a complex microenvironment of indoor allergens, pollutants, and other exposures. The school represents an occupational model for children and exposures in this environment have a significant health effect. Current research establishes an association between school exposure and asthma morbidity in children. This review will focus on common school environmental exposures (cockroach, rodents, cat, dog, classroom pets, dust mite, fungus, and pollution) and their impact on children with allergies and asthma. Understanding and evaluation of school-based environments is needed to help guide school-based interventions. School-based interventions have the potential for substantial benefit to the individual, school, community, and public health. However, there is a paucity data on school-based environmental interventions and health outcomes. The studies performed to date are small and cross-sectional with no control for home exposures. Randomized controlled school-based environmental intervention trials are needed to assess health outcomes and the cost-effectiveness of these interventions. The School Inner-City Asthma Intervention Study (SICAS 2), a NIH/NIAID randomized controlled clinical trial using environmental interventions modeled from successful home-based interventions, is currently underway with health outcome results pending. If efficacious, these interventions could potentially help further guide school-based interventions potentially with policy implications. In the meanwhile, the allergist/immunologist can continue to play a vital role in improving the quality of life in children with allergies and asthma at school through the use of the ADA policy and Section 504 of the Rehabilitation Act as well as encouraging adoption of toolkits to build successful school-based asthma programs and asthma-friendly schools.

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.

School Environmental Intervention Programs

Exposure to indoor allergens and pollutants plays a significant part in the development of asthma and its associated morbidity. Inner-city children with asthma are disproportionately affected by these exposures with increased asthma morbidity. Although years of previous research have linked exposures in the urban home environment with significant childhood asthma disease, many of these allergens are also present in inner-city school environments. Therefore, evaluation of the school environment of patients with asthma is also essential. School-based environmental interventions may offer benefit for this problem and has the potential to help many children with asthma at once in a cost-effective manner. It is important that environmental health researchers continue to assess which interventions are most practical and result in the greatest measurable improvements.

How In Vitro Assays Contribute to Allergy Diagnosis

Diagnosis of allergic disorders is based upon the clinical history of the disease, the immunoglobulin E (IgE) antibody response, and the allergen exposure. During the last decade, many changes have occurred in the in vitro diagnostic tests used in daily practice. The most important one is the use of allergenic molecules, which helps to define severe profile of allergy and/or to better understand cross-reactivity. The correlation between IgE sensitization and bronchial or nasal response in provocation tests is not so clear, which implies that such tests are still helpful in allergy diagnosis. In order to strengthen the link between a real allergen exposure and allergic symptoms, environmental allergen load assessment can be performed. For clinicians, it appears obvious to know the pollen count to treat their patients; however, they rarely measure the allergen load in the indoor environment, while nowadays home-tests (semi-quantitative or quantitative) make the assessment very easy. In the future, assessment of the environmental exposure (preferably with an indoor technician) of an allergic patient should take into account not only the allergens but also the other indoor pollutants, which could enhance respiratory symptoms in allergic patients.

Recent advances in environmental controls outside the home setting

PURPOSE OF REVIEW

It has been well studied that aeroallergen, mold, and airborne pollutant exposure in the inner-city home environment is associated with significant childhood asthma morbidity. Although the home environment has been extensively studied, the school environment is less well understood.

RECENT FINDINGS

In this article, we discuss the relationship between environmental exposures within the school and daycare environment and pediatric asthma morbidity and novel environmental interventions designed to help mitigate pediatric asthma morbidity.

SUMMARY

Studies assessing environmental exposures outside the home environment and interventions to mitigate these exposures have the potential to reduce pediatric asthma morbidity. Further study in this area should focus on the complex cost benefit analyses of environmental interventions outside the home setting, while controlling for the home environment.

The school environment and asthma in childhood

In this article, we discuss the relationship between environmental exposures within the school environment and pediatric asthma morbidity. This article will conclude by reviewing novel school based asthma education and therapeutic programs and environmental interventions designed to help mitigate pediatric asthma morbidity.

Introducing an environmental assessment and intervention program in inner-city schools

Home-based environmental interventions have demonstrated clinical benefit for children with asthma. Although much is known about school-based exposures, few studies have comprehensively examined the role the school environment plays in asthma and how effectively changing the environment might reduce morbidity when adjusting for exposures in the home. This review summarizes the importance and common challenges of school-based environmental assessment and intervention studies linked to health effects. We focus on the key components of study development and the challenges and benefits to implementation.

The school inner-city asthma study: design, methods, and lessons learned

BACKGROUND

Children spend a significant amount of time in school. Little is known about the role of allergen exposure in school environments and asthma morbidity.

OBJECTIVES

The School Inner-City Asthma Study (SICAS) is a National Institutes of Health (NIH)-funded prospective study evaluating the school/classroom-specific risk factors and asthma morbidity among urban children.

METHODS/RESULTS

This article describes the design, methods, and important lessons learned from this extensive investigation. A single center is recruiting 500 elementary school-aged children, all of whom attend inner-city metropolitan schools. The primary hypothesis is that exposure to common indoor allergens in the classroom will increase the risk of asthma morbidity in children with asthma, even after controlling for home allergen exposures. The protocol includes screening surveys of entire schools and baseline eligibility assessments obtained in the spring prior to the academic year. Extensive baseline clinical visits are being conducted among eligible children with asthma during the summer prior to the academic school year. Environmental classroom/school assessments including settled dust and air sampling for allergen, mold, air pollution, and inspection data are collected twice during the academic school year and one home dust sample linked to the enrolled student. Clinical outcomes are measured every 3 months during the academic school year.

CONCLUSION

The overall goal of SICAS is to complete the first study of its kind to better understand school-specific urban environmental factors on childhood asthma morbidity. We also discuss the unique challenges related to school-based urban research and lessons being learned from recruiting such a cohort.

Bla g 1 allergen levels in Zagreb area household dust

Cockroach allergy is a health problem in many parts of the world. In urban environments, indoor exposure to cockroach allergens involves a risk of asthma. The aim of this study was to measure the mass fraction of Bla g 1, a major allergen of the German cockroach (Blatella germanica) in 30 house samples, collected at random from Zagreb area households, Croatia. Dust samples were collected on cellulose filters by vacuuming living rooms floors. After extraction, Bla g 1 was detected using the commercial enzyme-linked immunosorbent assay (ELISA). Only four of the thirty households had detectable Bla g 1 levels, and only in one was its concentration higher than 2.0 U g(-1), the threshold associated with sensitisation. The Bla g 1 ELISA proved highly sensitive, with the detection limit of 0.12 U g(-1). The within- and between-assay imprecision was 8.9 % and 14.4 %, respectively, and accuracy 85 % to 120 %. Low Bla g 1 levels in the household dust support previously reported low prevalence of skin sensitisation to B. germanica among Zagreb residents. Further monitoring should reveal if there are differences in cockroach allergen exposure and sensitisation between households from other geographic areas in Croatia.

Domestic exposure to aeroallergens in Hong Kong families with asthmatic children

Indoor aeroallergen exposures increased asthma symptoms in Caucasians, but their determinants and relationship to asthma and allergy in Asians are unclear. This study investigated exposures to cat, cockroach, and Blomia tropicalis allergens in 115 Hong Kong families with asthmatic children. Patients underwent exhaled nitric oxide and spirometric measurements. Home visits were made within 2 weeks during which parents completed a standardized questionnaire. Fel d 1, Bla g 2, and Blo t 5 in dust samples collected from patients' mattresses, bedroom floors, and living room floors were measured by immunoassays. These aeroallergens were only detectable in some homes (38-55% for Fel d 1; 9-21% for Bla g 2, and 7-14% for Blo t 5). The presence of cat and/or dog was a strong determinant for Fel d 1 in all indoor sites. The timing and frequency of bedding change was associated with Bla g 2 levels, whereas the timing of bedroom floor cleaning was a consistent factor for Blo t 5 levels. Asthmatic children in families with high allergen exposure were more likely to have ≥4 wheezing attacks in preceding 12 months and exercise-induced wheezing than those with normal allergen exposure (P = 0.051 and 0.030, respectively). Mattress levels of all three allergens were also associated with severity of several allergy symptoms (P = 0.025-0.005). None of these aeroallergens correlated with exhaled nitric oxide and spirometric parameters. This study identifies determinants for cat, cockroach, and B. tropicalis levels in Hong Kong families with asthmatic children. These exposures are associated with severity of allergy symptoms.

Pest and allergen exposure and abatement in inner-city asthma: a work group report of the American Academy of Allergy, Asthma & Immunology Indoor Allergy/Air Pollution Committee

Our work group report details the importance of pest allergen exposure in inner-city asthma. We will focus specifically on mouse and cockroach exposure. We will discuss how exposure to these pests is common in the inner city and what conditions exist in urban areas that might lead to increased exposure. We will discuss how exposure is associated with allergen sensitization and asthma morbidity. Finally, we will discuss different methods of intervention and the effectiveness of these tactics.

Home and school environmental assessment and remediation

Children spend a considerable portion of their time indoors. Therefore, homes and schools are an important source of allergen exposure. Chronic exposure to the major indoor allergens can lead to allergic sensitization and provoke allergic symptoms in children. Environmental assessment is crucial for the identification and quantification of such allergens in indoor spaces. Reduction of allergen exposure below sensitization and symptom thresholds is possible with various remediation techniques. This article reviews and discusses evidence for the assessment and remediation of indoor allergens commonly found in homes and schools. A literature review was performed using the PubMed database for English-language articles published between January 1, 1980, and February 2009. Additional information was obtained from a review of recent textbooks and one professional society's webpage.

Indoor allergens in Minnesota schools and child care centers

Elevated concentrations of allergens in the indoor environment may cause allergic sensitization and symptoms. Occupant exposure to indoor allergens in educational facilities should and can be controlled. This study (1) assessed the presence of indoor allergens in Minnesota schools and child care centers, (2) characterized the distribution of allergens in different materials, and (3) evaluated the effect of building and maintenance interventions on allergen concentrations. Settled dust samples were collected from carpet, vinyl tile floors, and upholstered furniture in six schools and seven child care centers before and after interventions. Interventions included changes to cleaning, ventilation, entry mats, furnishings, flooring, and classroom items. The amount of total dust, culturable fungi, and indoor allergens--cockroach, dust mite, cat, and dog--were quantified in the dust samples. Cockroach and dust mite allergens were generally low and below the detection limit, but one dust mite allergen was detected in some areas. Cat and dog allergens were frequently detected at elevated levels, with half the samples above the provisional sensitization risk thresholds and a few samples above the symptom thresholds. Allergen concentrations were highest in upholstered furniture, followed by carpeting and then vinyl floor tile. Cat and dog allergens were lower after the interventions. Cat and dog allergens, but not dust mite and cockroach allergens, seem to be ubiquitous in child care and elementary schools of the U.S. Midwest. These allergens may contribute to sensitization in atopic individuals and occasionally cause symptoms in sensitized allergic individuals. Fleecy materials that are not adequately cleaned, such as upholstered furniture, appear to be the most significant allergen reservoirs. Modest environmental interventions can be implemented by building staff, which should result in lower allergen concentrations.

Indoor allergens in school and day care environments

Most studies that have examined exposure to indoor allergens have focused on home environments. However, allergen exposures can be encountered in environments other than the home. For example, many children spend a large part of their time in schools and day care facilities. Over the past 2 decades, a large number of studies have been conducted in school and day care environments. However, the role of indoor exposures in allergy and asthma development or morbidity in these settings is not well characterized. The purpose of this review is to evaluate the importance of indoor allergen exposures in school and day care settings. We summarize the key findings from recent scientific literature, describe exposure characteristics, discuss the role of these exposures in relation to asthma and allergy symptoms, and provide information on the effectiveness of published interventions.

German cockroach allergen levels in North Carolina schools: comparison of integrated pest management and conventional cockroach control

Cockroach suppression is fundamental to cockroach allergen mitigation in infested homes. The effects of various cockroach control strategies on cockroach populations and allergen concentration have not been examined in schools. This study was conducted to compare the effectiveness of integrated pest management (IPM) and conventional pest control in controlling German cockroach (Blattella germanica L.) infestations and concentrations of the cockroach allergen Bla g 1 in public school buildings. Two school districts included six schools that used conventional pest control and one district included seven schools that used IPM to control pests. Cockroach traps were deployed to assess the level of infestation, settled dust samples were collected in food service areas, classrooms, and other school areas, and the Bla g 1 allergen was quantified by ELISA. Both cockroach counts and Bla g 1 concentrations were dependent on the pest control approach, with highly significant differences between IPM-treated schools and conventionally treated schools in both the cockroach mean trap counts (0 versus 82.6 +/- 17.3 cockroaches/trap/wk, respectively) and in the amount of Bla g 1 in dust samples (2.8 +/- 0.3 versus 30.6 +/- 3.4 U/g dust). Cockroaches and Bla g 1 were primarily associated with food preparation and food service areas and much less with classrooms and offices. Our data extend recent findings from studies in homes, showing that cockroach allergens can be reduced by cockroach elimination alone or by integrating several tactics including education, cleaning, and pest control. IPM is not only effective at controlling cockroaches but also can lead to long-term reductions in cockroach allergen concentrations, resulting in a healthier environment for students and school personnel.

Mouse allergens in urban elementary schools and homes of children with asthma

BACKGROUND

The association between allergens in schools and childhood asthma has not been well studied, particularly in the United States.

OBJECTIVE

To investigate allergen exposure in schools compared with homes with a specific focus on children with asthma.

METHODS

Dust samples were collected from 46 rooms in 4 urban elementary schools (northeastern United States) and from 38 student bedrooms. Samples were analyzed for cat (Fel d 1), dog (Can f 1), cockroach (Bla g 2), dust mites (Der f 1/Der p 1), and mouse urinary protein (MUP). Questionnaires identified students with physician-diagnosed asthma.

RESULTS

Cat and dog allergens were detectable in most school samples (96% and 78%, respectively), but at low levels. Cockroach allergen was detectable in only 11% of school samples. Mouse allergen was detectable in 89% of school samples, with 68% having MUP levels greater than 0.5 microg/g. In contrast, MUP was detectable in only 26% of bedroom samples. Matched classroom and home samples from 23 asthmatic students showed higher geometric mean MUP levels in the classroom vs the home (6.45 microg/g vs 0.44 microg/g, P < .001). However, there were lower geometric mean dust mite (Der f 1) levels in the classroom vs the home (0.04 microg/g vs 0.66 microg/g, P < .001).

CONCLUSIONS

There are significantly higher levels of MUP but lower levels of Der f 1 in schools vs homes. It is important to recognize that children with asthma may encounter varying levels of allergens in environments outside the home, such as schools.

Prevalence of allergic rhinitis in 3-6-year-old children in Wuhan of China

BACKGROUND

Only a few prevalence studies of allergic rhinitis (AR) have been reported in China. This study aimed to evaluate the prevalence of AR in a population of 3-6-year-old children in Wuhan, China.

METHODS

Sixteen kindergartens in Wuhan City were randomly selected; for each kindergarten, there were three classes from three grades (top, middle and bottom grade, 3-6 years old, respectively). Questionnaires generated by the authors were distributed and filled out by parents of the selected children, with a telephone interview subsequently. Skin prick test (SPT) was carried out on the children after a written consent was signed by the parents.

RESULTS

A total of 1211 (89.5%) valid questionnaires were returned for evaluation. The adjusted current prevalence of AR in 3-6-year-old children was 10.8% with the diagnostic criterion of nasal symptoms(+) and SPTs(+). In the SPTs(+) children, the most common inhalant allergen was house dust mites (94.7%), followed by moulds (28.4%). The prevalence of AR was higher in males than that in females (13.0% vs. 7.7%, P < 0.05). 15.8% and 23.2% of AR children were sensitive to egg and milk, respectively. The percentage of children sensitive to both inhalant and food allergens was 27.4%.

CONCLUSIONS

We found an unexpectedly high prevalence of diagnosed AR in 3-6-year-old children within the investigated population. Dust mite was the most important allergen source for 3-6-year-old children in Wuhan.

Cockroach allergen biology and mitigation in the indoor environment

For nearly a half century, cockroaches have been recognized as a major cause of asthma morbidity in the urban, inner-city environment. Several cockroach-produced allergens have been identified and characterized, and a few have been produced as recombinant proteins. Recent research has moved beyond clinical, patient-based investigations to a more entomological perspective that addresses the production, physiological regulation, and developmental expression of cockroach allergens, thus providing insight into their functional biology and their relationship to current cockroach control strategies. Although successful removal of cockroach allergens from the infested environment has been difficult to accomplish with remedial sanitation, large-scale reductions in cockroach allergens below clinically relevant thresholds have recently been realized through suppression of cockroach populations. Here we review the current understanding of cockroach allergen biology and the demographics associated with human exposure and sensitization. We also critically evaluate allergen mitigation studies from an entomological perspective, highlighting disparities between successful and failed attempts to lessen the cockroach allergen burden in homes.

Allergens in school settings: results of environmental assessments in 3 city school systems

Environmental allergens are major triggers for pediatric asthma. While children's greatest exposure to indoor allergens is in the home, other public places where children spend a large amount of time, such as school and day care centers, may also be sources of significant allergen encounters. The purpose of this article is to describe schoolroom allergen levels from 3 different geographic sites obtained from dust samples collected in the fall and in spring. Environmental dust samples were collected from elementary schools in Birmingham (AL), Detroit (MI), and Houston (TX), from 4 room locations, including the cafeteria, library, upper grades, and lower grades. Samples were assayed for dust mite (Dermatophagoides pteronyssinus and Dermatophagoides farinae), cat (Felis domesticus), and cockroach (Blatella germanica 2) allergen levels. Allergen levels varied by geographic location and type of schoolroom. Schoolroom settings differed by the type of flooring (hard and carpet), room characteristics and use (food service, library shelves with books, and general classroom with multiple types of materials [individual desks and different types of furniture]), and the average age of the schoolroom dwellers (younger vs. older children). Dust mite, cat, and cockroach allergens were present in all schoolrooms and all sites at varying levels by season and by type of room. Schools may be important sources of direct allergen exposure and reservoirs that could potentially contribute to allergic sensitization and disease exacerbation in children. Further studies are needed to carefully examine the environmental allergen load in schools and its effect on children.

Allergic rhinoconjunctivitis: epidemiology

Allergic rhinoconjunctivitis has been studied much less frequently than asthma using epidemiologic approaches. Population-based studies are difficult to conduct because of misclassification arising from the reliance on self-reported questionnaires that use terms such as allergic rhinitis or hay fever to establish the diagnosis. In addition, many epidemiologic studies focus on diagnostic skin testing or allergen-specific IgE antibodies (RASTs) as an objective outcome to assess for hay fever. These techniques are helpful but not perfect measures for predicting hay fever outcomes in epidemiologic studies. It is generally accepted, however, that allergic rhinoconjunctivitis is one of the most common of chronic diseases and is the most common atopic disorder. This article reviews the definition of allergic rhinoconjunctivitis, the epidemiology of this disorder from infancy into adulthood, and environmental risk factors for development of sensitization to certain allergens.

Mouse and cockroach allergens in the dust and air in northeastern United States inner-city public high schools

Considering that high school students spend a large proportion of their waking hours in the school environment, this could be an important location for exposure to indoor allergens. We have investigated the levels of mouse and cockroach allergens in the settled dust and air from 11 schools in a major northeastern US city. Settled dust samples were vacuumed from 87 classrooms, three times throughout the school year. Two separate air samples (flow = 2.5 lpm) were collected by 53 students over a 5-day period from both their school and their home. Mouse allergen (MUP) in the dust varied greatly between schools with geometric means ranging from 0.21 to 133 microg/g. Mouse allergen was detectable in 81% of the samples collected. Cockroach allergen (Bla g 2) ranged from below limit of detection (<0.003 microg/g) to 1.1 microg/g. Cockroach allergen was detected (>0.003 microg/g) in 71% of the dust samples. Bla g 2 was detected in 22% of airborne samples from the schools. By comparison, mouse allergen was only detected in 5%. These results indicate that the school may be an important location for exposure to allergens from mice and cockroaches and is an indoor environment that should be considered in an overall allergen intervention strategy.

PRACTICAL IMPLICATIONS

To date, cockroach and mouse allergen intervention strategies have been mainly focused on the home environment. Considering that children spend a significant amount of time in schools, some studies have assessed cockroach allergen levels in schools. This study provides a clearer picture of the distribution and variability of not only cockroach allergen, but also mouse allergen in the school environment. In addition, this study describes limitations of personal air sampling in a student population. Our results suggest that although cockroach and mouse allergens are commonly recovered in classroom dust samples of inner city schools, cockroach allergens are recovered in the personal air samples with a greater frequency relative to mouse allergens.

Indoor allergens in settled school dust: a review of findings and significant factors

The school environment can be an important site of exposure to cat, dog, dust mite, and cockroach allergens, which have been detected in the settled dust of many schools. The sizable body of research that has been published in recent years warrants careful examination. This review article informs clinicians, researchers, and other parties about the potential for exposure in the school environment, factors that affect allergen concentrations, and areas of future research. While average concentrations in schools were usually under risk levels for symptoms or sensitization, many studies reported at least one location where the concentrations exceeded these levels. Maintenance, mechanical, and administrative factors were related to allergen levels in schools. From a clinical perspective, the school environment in industrialized nations has a lower potential for exposure than the home environment, but schools are significant for allergic individuals whose home environment has been addressed to the extent feasible. From a public health perspective, the school environment should be considered as a target for primary and secondary prevention. It can be more practical and amenable to intervene on a single school than the hundreds of homes in a community. Future research should continue to evaluate which interventions are most practical and result in the greatest measurable improvements. In addition, research should further examine the relationship between allergen exposure in schools and health effects, in order to develop an accurate exposure assessment model and risk levels that are specific to the school environment.

Control of environmental allergens as a therapeutic approach

The first rule of environmental allergen control is that avoidance is appropriate for allergic patients with asthma. Although this rule is obvious to allergists, it frequently is not considered by families and physicians who are not trained in allergy. The next step in environmental avoidance is to determine the specific sensitivity of a patient. Clinically, practitioners have to address reduction of exposure to more than one allergen, and it is likely that the complexity of dealing with several treatment regimes decreases compliance.

Environmental allergens and asthma in urban elementary schools

BACKGROUND

Asthma in school children is rising, and indoor allergens are very common triggers of asthma attacks; however, the risk of the school environment on asthma has not been well studied.

OBJECTIVE

To determine the presence and the levels of common aeroallergens in schools, where asthma prevalence rates are high.

METHODS

Settled dust samples were collected from 12 Baltimore City public elementary schools, and they were analyzed for the following allergens: cockroaches (Bla g 1/2), dust mites (Der f 1/p 1), dog (Can f 1), cat (Fel d 1), and mouse (Mus m 1). School asthma prevalence rates were correlated with allergen levels, and association between allergen levels and other risk factors present in the schools' environment was examined.

RESULTS

The mean and range levels were 1.49 U/g (0 to 8) for Bla g 1/2; 0.38 microg/g (0 to 11.9) for the Der f 1/p 1; 1.44 microg/g (0.1 to 9.6) for Can f 1; 1.66 microg/g (0.2 to 12) for Fel d 1; and 6.24 microg/g (0.3 to 118.3) for Mus m 1. Dust mite, cat and dog allergens were significantly in rooms with carpet and/or area rugs, compared to rooms with bare floors (P < 0.05). Asthma prevalence rates varied from 11.8 to 20.8% between schools and positively correlation with the mean levels of Bla g 1/2 in the schools (P = 0.001).

CONCLUSIONS

Common allergens that are known to trigger asthma were detected in all school environments, where asthma prevalence rates were high. However, the overall allergen levels were low, indicating that other factors, including exposures in the homes of asthmatic patients, may have more relevance to sensitization and symptoms than school exposures.

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

BACKGROUND

Public places, including schools, have been identified as sources of exposure to allergens derived from mites, cockroach, cat, and dog and to endotoxin.

OBJECTIVES

The purposes of this study were to assess and compare exposure to allergens and endotoxin in 4 types of public child-care facilities in Brazil and to investigate whether the presence of children and the performance of cleaning procedures could have an influence on allergen and endotoxin levels.

METHODS

We have analyzed dust from bedding, floors, chairs, and tables of daycare centers (DCs), preschools, kindergartens, and elementary schools (ESs). Major allergens from mites, cockroach, cat, and dog were quantitated by means of ELISA, and endotoxin content was determined by using the Limulus Amebocyte Lysate assay.

RESULTS

Group 1 mite allergens were greater than 2 microg/g in 67% of DC and preschool samples and in 8.9% and 2.2% of kindergarten and ES samples, respectively. The presence of bedding in DCs and preschools accounted for increased levels of mite allergens in these settings. Levels of Bla g 1 were higher in ES floors compared with those found in DC and preschool floors. Low levels (<1 microg/g) of Fel d 1 e Can f 1 were found in most samples. Levels of endotoxin in DCs and preschools were 3 times higher than in ESs.

CONCLUSIONS

DCs and schools in Brazil should be considered as important sources of exposure to dust mites and cockroach allergens and to endotoxin. Recommendations for mite allergen avoidance should include appropriate care of bedding in DCs and preschools.

Arthropod allergens and human health

Many species of arthropods are the sources of potent allergens that sensitize and induce IgE-mediated allergic reactions in humans. Most of these arthropod allergens are proteins, and the allergic response mechanism to these allergens is the same as it is for allergens from other sources such as plant pollens, molds, and foods. Aside from ingestion of crustaceans (shrimp, lobster), among arthropods, humans have the greatest contact with insects and mites, and as a result allergies to these two groups of arthropods have been the most frequently reported. Because of the large number of people affected by allergic reactions to stinging insects, cockroaches, and dust mites, many allergens of these organisms have been extensively studied, purified, and immunobiochemically characterized and for some recombinant allergens, produced. Cocktails of these recombinant allergens have the potential for use in diagnosis and immunotherapy. In this chapter, we review the insects and mites that induce allergic reactions. Where the information exists, the immunobiochemical characterization of the allergens and the frequency of sensitivity or clinical reactivity in the human population are also reviewed. As background, the beginning of this review includes sections that define allergens, explain the allergic reaction mechanism, and describe the methods for naming allergens.

Cockroach allergens: environmental distribution and relationship to disease

Cockroach allergy has been recognized as an important cause of asthma. Exposure to high levels of cockroach allergens in the home is a major risk factor for symptoms in sensitized individuals. Previously identified allergens from Blatella germanica and Periplaneta americana include Bla g 2 (inactive aspartic proteinase), Bla g 4 (calycin), Bla g 5 (glutathione-S-transferase), Bla g 6 (troponin), the Group 1 cross-reactive allergens Bla g 1 and Per a 1, Per a 3 (arylphorin), and Per a 7 (tropomyosin). The primary site of cockroach allergen accumulation is the kitchen. However, lower levels of allergen can be found in bedding, on the bedroom floor, and in sofa dust. Strategies for decreasing exposure to cockroach have been investigated. The results suggest that a sustained decrease in cockroach allergen levels is difficult to accomplish, even after successful extermination of cockroach populations. The use of recombinant cockroach allergens may lead to the development of new approaches to asthma treatment in the future.

House dust mite, cat, and cockroach allergen concentrations in daycare centers in Tampa, Florida

BACKGROUND

Allergen exposure in early childhood is a risk factor for sensitization and the development of asthma. Studies performed in Europe, New Zealand, and Singapore indicated the presence of indoor allergens in childcare centers and schools. However, the importance of indoor allergens in daycare centers in humid and warm regions of the world is not known.

OBJECTIVE

To measure total mite counts, Der p 1, Der f 1, Fel d 1, and Per a 1 allergens in dust samples and mite allergen airborne concentrations in daycare centers in Tampa, Florida, United States.

METHODS

Twenty daycare centers were surveyed for mite, cat, and cockroach allergens in Tampa, FL. One dust and two air samples (one during the day and one during the night) were collected in each center. Dust samples were extracted and analyzed for mite (Der p 1 and Der f 1), cat (Fel d 1), and cockroach (Per a 1) allergens. Mite airborne allergen concentrations were analyzed by RAST inhibition and expressed in standardized mite allergen units per m3 of air (AU/m3).

RESULTS

Mites were identified in 15 samples, and concentrations ranged from 10 to 1,200 mites/g (298 +/- 355.2). The most prevalent mite species was Dermatophagoides pteronyssinus ( Der p 1). Der p 1 and/or Der f 1 were detected in 10 daycare centers. Der p 1 was detected in eight centers and ranged from I to 21.8 microg/g of dust (5.4 +/- 6.9); Der f 1 was detected in 3 centers and ranged from 0.2 to 2.1 microg/g of dust (1.3 +/- 0.9). Per a 1 and Fel d 1 were detected in all centers in small quantities; Per a 1 ranged from 8 to 1,806 ng/g (263.1 +/- 449.7) and Fel d 1 from 0.2 to 120 U/g of dust (16.6 +/- 31.7), respectively. Airborne mite allergen was detected in 18 centers and ranged from 0.01 to 2.7 AU/m3 during the day (0.2 +/- 0.6) and from 0.01 to 0.12 AU/m3 during the night (0.06 +/- 0.03), P = 0.001.

CONCLUSIONS

Mite, cat, and cockroach allergens are present in daycare centers in Tampa, FL. Mite allergen concentrations exceeded levels that have been associated with sensitization and symptoms in allergic subjects in 40% of these centers.

A comparative study on cockroach and ovalbumin sensitizations and challenge responses in Hartley guinea-pigs

The role of allergens in asthmatic inflammation is not clearly understood. To elucidate the mechanism of cockroach allergen (CRa)-induced airway disease, we studied three groups of Hartley guinea-pigs sensitized to control, ovalbumin (OA) or CRa. Parameters measured were anaphylactic antibodies by allergy skin test (AST), PCA assay and Western blot, changes in specific airway resistance (SRaw), analysis of bronchoalveolar lavage (BAL) and contracture responses of tracheal muscle (TSM) to non-specific and specific stimuli, in vitro. Both OA and CRa animals showed a similar allergic sensitization (AST and PCA), while Western blot identified several reaginic bands in CRa group compared to a single band in OA group. SRaw illustrated that CRa induce dual-asthmatic responses (4/6) in the CRa group, whereas OA induce only an early asthmatic response (3/6) in the OA group (P<0.01). The average total leukocytes in BALF of the CRa were 27.0x10(6), mostly neutrophils and eosinophils, while those of the OA showed 3.5x10(6), mostly eosinophils, respectively (P<0.0001). TSM responses to non-specific stimuli were similar in both groups (P>0.1), while the antigen-specific TSM contractions were more brisk in the OA group than those of CRa group (P<0.001). Thus, the study indicates that both CRa and OA sensitize guinea-pigs, yet CRa induces more severe and persistent late-phase inflammation than OA. This appears to be related to an influx of neutrophils rather than anaphylactic bronchospasm.

Ecology and elimination of cockroaches and allergens in the home

Cockroach infestations have been indicated as a major contributor to asthma throughout the world. Several studies have shown that large numbers of asthmatic patients are sensitized to cockroach allergens. Eliminating this pest from homes, schools, and public buildings involves a long-term commitment to a rational extermination process. This article covers the characteristics of the major cockroach species that invade homes, assesses the role of environmental exposure to cockroaches in asthma, and provides an intervention program for their extermination.

The role of cockroach allergens in asthma

Cockroach allergy has been recognized as an important cause of asthma. Cockroach asthma has been described as a more severe disease, associated with perennial symptoms and high levels of total IgE. Cockroaches produce several allergens that induce sensitization, and exposure to high levels of cockroach allergens in the home is a major risk factor for symptoms in sensitized individuals. Previously identified allergens from Blattella germanica and Periplaneta americana, the most important domiciliary species, include Bla g 2 (inactive aspartic protease), Bla g 4 (calycin), Bla g 5 (glutathione-S-transferase), Bla g 6 (troponin), the Group 1 cross-reactive allergens Bla g 1 and Per a 1, Per a 3 (arylphorin), and Per a 7 (tropomyosin). Strategies for decreasing environmental exposure to cockroach have been recently investigated. The results suggest that a sustained decrease in cockroach allergen levels is difficult to accomplish, even after successful extermination of cockroach populations. Cockroach allergens have been cloned and produced as recombinant proteins in high-level expression vectors. The use of recombinant cockroach allergens should allow mechanisms of cockroach-induced asthma to be investigated and may lead to the development of new approaches to asthma treatment in the future.

Measurement and characterization of cockroach allergens detected during normal domestic activity

BACKGROUND

Cockroach allergen is recognized as a causal factor for asthma. However, airborne cockroach allergen has not been detected in undisturbed conditions, and therefore the behavior and properties of airborne cockroach allergen have been poorly characterized. A new aeroallergen sampling method and sensitive system of immunoassay have been used to examine cockroach allergen exposure.

OBJECTIVE

Our purpose was to measure and characterize airborne cockroach allergens during normal domestic exposure in the homes of Sydney, Australia.

METHODS

Air sampling with Institute of Occupational Medicine, Edinburgh (IOM) samplers was performed in the living rooms of 10 houses during low- and no-disturbance environments. In addition, inhaled particles were collected by each home occupant during low domestic exposure with use of intra-nasal samplers that impact particles onto an adhesive surface. The particles collected on the IOMs and the intra-nasal samplers were immunostained with Bla g 1 monoclonal antibodies. Particle size, morphologic characteristics, and the relative Bla g 1 content of particles were estimated. Reservoir dust samples from the kitchen, living room, and bedroom were assayed by an ELISA. Two forms of repeatability of IOM air sampling were examined. The first measure tested the repeatability of 2 IOM samples collected simultaneously in the same room during low- and no-disturbance activities. The second measure examined the repeatability of IOM sampling over time on 10 consecutive days.

RESULTS

Bla g 1 was detected in reservoir dust samples taken from all homes (geometric mean 1.5 U/g, range 0.2-9.4 U/g). Inhaled particles containing Bla g 1 were detected during 1 hour of intra-nasal sampling in 8 of 10 homes during low disturbance. Cockroach particles were detected on all of the IOM samples collected for both 4-hour low-disturbance and overnight no-disturbance sampling environments. Particles containing Bla g 1 collected with the IOM samplers during low disturbance ranged in size from 3 to 350 microm. These particles are amorphous and irregular in shape, and a majority of the large particles were described as flakes (flat, transparent particles) and fibers (threadlike). A relationship was demonstrated between the allergen content of cockroach particles and their particle size. The larger particles elute more Bla g 1. The coefficient of repeatability for measurements made during low and no disturbance was 3.62 and 2.09, respectively. For measurements repeated over time at the same site, the coefficient of repeatability was 2.61. This represents the fold range within which 95% of pairs of measurements made at an interval of 1 day would be expected to lie.

CONCLUSIONS

Airborne cockroach allergen is present in both undisturbed and low-disturbance environments in homes with relatively low reservoir levels of Bla g 1. In agreement with previous reports, airborne particles containing cockroach allergen (Bla g 1) are mainly associated with particles >10 microm. These particles are amorphous and irregular in shape and can be described as flakes and fibers.

Relevance of allergens from cats and dogs to asthma in the northernmost province of Sweden: schools as a major site of exposure

BACKGROUND

The prevalence of asthma in the northernmost region of Sweden has been estimated at 6% to 8% in spite of the very dry climate. The causes of the increase in asthma are not clear, but conditions are unfavorable for dust mite growth, and domestic animals are thought to be the primary source of indoor allergens.

OBJECTIVES

We sought to investigate the relationship between asthma, exposure, and sensitization in Northern Sweden, with a focus on the role of schools.

METHODS

Serum was collected from 110 asthmatic children, 55 children with symptoms of asthma but no established diagnosis, and 63 control children (age, 7 and 8 years). Total IgE and specific IgE to 7 allergens were measured. Dust samples were collected from the classrooms of 7- and 8-year-old children in 22 schools from Kiruna and Luleâ, Sweden. For comparison, dust was also collected from 24 homes in Kiruna and 2 schools in Virginia in the United States.

RESULTS

Serum IgE antibody assays on 165 children with respiratory symptoms confirmed that there was a high degree of sensitization to cat, dog, and birch in Northern Sweden. Cat and dog allergens were present in almost all of the school samples in Sweden. By contrast, dust mite and cockroach allergens were generally unmeasurable. The highest levels of cat and dog allergens were found in samples from desks and chairs. Cat and dog allergen levels in the schools were comparable with but higher than those in the homes without pets. The schools in Virginia had similar allergen levels, except that samples from this humid region also had significant mite allergen.

CONCLUSIONS

In this climate the primary sensitization associated with asthma is to cat dander and dog dander but also to birch pollen. Mite and cockroach allergens were not present in the dust samples, and sensitization to these allergens was not significant. The schools appear to be a major site of exposure to cat and dog allergens. These results are relevant both to an understanding of the reasons for the increase in asthma in this region and to any proposal to reduce exposure to allergens.

Molecular cloning of Per a 1 and definition of the cross-reactive Group 1 cockroach allergens

BACKGROUND

Sensitization to allergens produced by German and American cockroaches is strongly associated with the cause of asthma. Most of the cockroach allergens identified to date have been species specific.

OBJECTIVE

The aim of this study was to identify and sequence cross-reactive cockroach allergens.

METHODS

A Periplaneta americana cDNA library was screened with IgE antibody from patients in the United States who were allergic to cockroach and who were sensitized to Blattella germanica.

RESULTS

A cDNA clone was isolated that contained an 870-bp sequence with a 695-bp open reading frame, encoding a 231 amino acid protein, molecular weight 26.2 kd. Plaque immunoassays using anti-Bla g 1 and anti-Per a 1 mAbs and a panel of human IgE antibodies showed that the protein expressed by these clones was Per a 1. Sequence homology searches showed that Per a 1 was homologous to 5 previously reported, but unidentified, sequences from B germanica and P americana. These sequences encoded proteins with multiple molecular sizes containing approximately 100 amino acid repeats. The Per a 1 sequence also showed 31% identity to a mosquito precursor protein, ANG12, which may be involved in digestion. The Per a 1 cDNA was expressed in Pichia pastoris to produce purified recombinant allergen (yield, 14 mg/L).

CONCLUSION

The results define the molecular structure and antigenic relationships between a new family of cross-reactive "Group 1" allergens produced by both P americana and B germanica. These recombinant allergens and specific mAbs will provide tools to improve the diagnosis and treatment of allergic diseases caused by cockroaches.

Methods and effectiveness of environmental control

In recent years the role of allergen exposure and atopy, and the interaction between them in the clinical expression of allergic disease, has been examined in a quantitative manner in epidemiologic studies. Such analyses suggest that avoidance of exposure to domestic allergens is a critical element in integrated strategies for both the prevention and the management of asthma. The promise of primary intervention in high-risk infants, as shown in the Isle of White study, has been confirmed in a recent study in Japan, and at least 4 similar trials are in progress. Applying these principles to the management of symptoms in patients with chronic asthma has proved more difficult, and it is likely that many earlier studies were poorly designed to test the hypothesis that allergen avoidance was clinically useful. Recent studies with patients moved to high altitudes during seasonal reductions in mite exposure and randomized controlled interventions in houses have all shown improvements in clinical manifestations of asthma. These recent trials have also demonstrated something that was less certain-that massive reductions in domestic allergen exposure can be achieved and that people will adopt the significant changes to their domestic environment and lifestyles if the risks and benefits are known. In the future, it seems likely that better study designs, as well as improvements in methods to monitor exposure and clinical outcomes, will provide further support for the role of allergen avoidance in the prevention and management of asthma.

Relationship of indoor allergen exposure to skin test sensitivity in inner-city children with asthma

BACKGROUND

It is important to understand the relationship between environmental allergen exposure dose and the risk of atopic individuals becoming sensitized to that allergen if we are to change the risk of sensitization and morbidity from allergic disease.

OBJECTIVE

The objective of these studies was to determine whether there was a dose response between current exposure to mite, cockroach, and cat allergen in inner-city children and to determine the prevalence of sensitization to these allergens.

METHODS

A sample of 500 children was selected from the 1528 children enrolled in the National Cooperative Inner City Asthma Study. Children were selected who had a sample of home dust and valid skin test responses performed with a MultiTest skin test device. The samples of home dust were collected from the floor and furniture in the kitchen, bedroom, and television/living room and were assayed for Der p 1, Der f 1, Bla g 1, and Fel d 1 allergens.

RESULTS

Each allergen level correlated significantly between rooms in individual homes. Mite (Der p 1 and Der f 1) and cat (Fel d 1) allergen levels were frequently below the detection limit of the assay. Cockroach allergen (Bla g 1) concentrations in the child's bedroom were related to the prevalence of positive skin test responses to cockroach allergen extract among the children, with an odds ratio for sensitization of 1.45 (1.11-1.92). Positive skin test responses to cockroach allergen were seen in 15% of children exposed to bedroom dust with a Bla g 1 concentration below the level of detection compared with a rate of 32% in bedrooms with Bla g 1 levels of 1 to 2 U/g and 40% to 44% among those in rooms with 4 U/g or greater. The relationship between exposure and positive skin test responses was clearly stronger among atopic children with a greater number of positive skin test responses.

CONCLUSIONS

Despite widespread exposure to household allergens, the strongest relationship between exposure and sensitization was seen in the bedroom. The dose response between exposure to cockroach allergen and sensitization suggested that exposure to low doses of allergen, 2 U/g or less, was a risk factor and that the risk plateaus above 4 U/g. Atopy modified the relationship of exposure to sensitization.

Skin test reactivity to indoor allergens as a marker of asthma severity in children with asthma

BACKGROUND

Specific IgE responses to common indoor aeroallergens in children with asthma have been found to be associated with acute asthma.

OBJECTIVE

The purpose of this study was to examine the association between asthma severity and skin test reactivity to four common indoor allergens.

METHODS

The charts of 139 asthmatic children, aged 5 to 18 years, seen in a pediatric allergy clinic were reviewed to obtain the results of skin tests to cat, dog, cockroach, and dust mite allergens, FEV1, anti-asthma medication requirements and demographic characteristics. Logistic regression for ordinal data was used to examine the association between skin test reactivity and asthma severity (mild, moderate or severe) as determined from FEV1 and medication usage.

RESULTS

The rate of allergen sensitivities were dust mite 55%, cockroach 50%, cat 29% and dog 17%. Children with positive skin test to cat allergen were more likely to have a higher asthma severity rating than children with a negative cat allergen skin test [proportional odds ratio (OR) = 3.0, 95% confidence interval (CI) = 1.4 to 6.1, P = .003]. This association remained significant after we controlled for skin test reaction to the other three allergens and various sociodemographic factors (adjusted OR = 3.0, 95% CI = 1.3 to 7.2, P = .013). The ORs for sensitivity to dog, cockroach, and dust mite allergen did not differ significantly from one, but children who were sensitized to all four allergens had an OR of 4.8 (95% CI = 1.3 to 18, P = .019) relative to children who were not sensitized to any of the four allergens. This association also remained significant after controlling for sociodemographic variables (P = .030).

CONCLUSION

Children with combined sensitivity to cat, dog, dust mite, and cockroach allergens were at increased risk of having more severe asthma. Our data also suggest that sensitization to cat allergen per se is a risk factor for more severe disease in these asthmatic children.