Allergen exposure, atopy and smoking as determinants of allergy to rats in a cohort of laboratory employees

Comparison of high- and low-molecular-weight sensitizing agents causing occupational asthma: an evidence-based insight

INTRODUCTION

The many substances used at the workplace that can cause sensitizer-induced occupational asthma are conventionally categorized into high-molecular-weight (HMW) agents and low-molecular-weight (LMW) agents, implying implicitly that these two categories of agents are associated with distinct phenotypic profiles and pathophysiological mechanisms.

AREAS COVERED

The authors conducted an evidence-based review of available data in order to identify the similarities and differences between HMW and LMW sensitizing agents.

EXPERT OPINION

Compared with LMW agents, HMW agents are associated with a few distinct clinical features (i.e. concomitant work-related rhinitis, incidence of immediate asthmatic reactions and increase in fractional exhaled nitric oxide upon exposure) and risk factors (i.e. atopy and smoking). However, some LMW agents may exhibit 'HMW-like' phenotypic characteristics, indicating that LMW agents are a heterogeneous group of agents and that pooling them into a single group may be misleading. Regardless of the presence of detectable specific IgE antibodies, both HMW and LMW agents are associated with a mixed Th1/Th2 immune response and a predominantly eosinophilic pattern of airway inflammation. Large-scale multicenter studies are needed that use objective diagnostic criteria and assessment of airway inflammatory biomarkers to identify the pathobiological pathways involved in OA caused by the various non-protein agents.

[An epidemiological and evolutionary profile of occupational asthma of Tunisian workers]

INTRODUCTION

This study aims to identify the epidemiological and occupational characteristics of patients with occupational asthma (OA) and to assess their clinical evolution and occupational outcomes.

METHODS

We carried out a descriptive epidemiological study over a period of five years (from 2012 to 2016) about the OA cases in the private sector reported in the Tunisian region of Zaghouan.

RESULTS

All in all, 165 OA cases were reported during the study period, representing an annual incidence of 733.3 cases per 1,000,000 workers in the private sector. Our study population was composed predominantly (85.5%) of women, whose mean age was 41.5±6.8years. More than three quarters of the affected persons were working in the automobile industry, and most illnesses (77%) were attributable to isocyanates. The mean time to onset of the respiratory symptoms was longer for low molecular weight agents (13.6±3.1years) compared to high molecular weight agents (12.0±3.9years) (P=0.0006). The majority of OA cases (66.7%) lost their jobs. Job loss was significantly more frequent among asthmatic women and workers with OA due to isocyanates. Among the 62 cases of OA for whom risk factors were eliminated, 45 nonetheless remained symptomatic.

CONCLUSION

Effective prevention strategies involving the various actors need to be implemented in work environments so as to reduce the frequency and the medico-legal repercussions of a disabling condition.

Occupational rhinitis

Occupational rhinitis (OR) has so far received little attention even though it shares common pathophysiological features and trigger factors and is closely associated with occupational asthma (OA). Work-related exposure to certain substances, such as animal dander, is considered to be the main factor for the development of OR. The new EAACI definition of OR stresses the causal relationship between workplace exposure and onset of rhinitis symptoms as opposed to previous definitions that mainly focused on a temporal relationship between workplace exposure and occurrence of nasal symptoms. Also, it has been suggested to use the term “work-related rhinitis” for classifying the different forms of rhinitis associated with the workplace. These forms can be subdivided into allergic or non-allergic OR, which is due to causes and conditions related to a particular work environment, as well as work-exacerbated rhinitis, which is defined as a pre-existing rhinitis exacerbated by exposure at the workplace. Even though taking a detailed patient history is especially important when it comes to diagnosing OR, the gold standard for confirming the diagnosis is nasal provocation testing. Best possible symptomatic relief and prevention of development of OA constitute the main therapeutic objectives in OR. Treatment options consist of total avoidance of trigger substances (main goal), reduction of exposure to certain substances, and pharmacotherapy. Furthermore, it is important to note that allergic OR is an occupational disease in Germany (Berufskrankheit No 4301) and needs to be reported to health authorities.

From workplace to home environment: spreading of mouse allergens by laboratory animal workers

PURPOSE

Laboratory animal workers (LAW) working with laboratory mice are exposed to mouse allergens (MA). If MA are spread to home environments, this might increase the risk for allergies in LAW and their families. This study aimed to assess 1. whether spreading of MA from workplace to home environment takes place; 2. which factors increase spreading of MA.

METHODS

In a cross-sectional study, dust samples were taken on the mattress and seating in homes of LAW (n = 105) and an unexposed comparison group (n = 13). From 89 LAW, additional dust samples were taken from their workplaces. Samples were analysed using Mus m1 ELISA kits [detection limit (DL) 0.2 ng mus m1/ml]. Sociodemographic data, personal history of allergies and cleaning habits, as well as work-related characteristics (LAW only) were assessed by questionnaire. Latent factors were assessed via factor analysis. Tobit models were fitted to analyse the latent factors' contribution to MA spreading.

RESULTS

MA concentration on the seating was significantly higher in home environments of LAW (median = 1.28 ng mus m1/m²) than in the comparison group (median < DL, p = 0.019). The highest workplace MA concentration was found on the floor of the scullery (median = 140,000.00 ng mus m1/m²), followed by hair-covering caps (median = 76.02 ng mus m1/m²). Cage and mouse facility cleaning tasks and infrequent changing of bed linen at home were statistically significantly associated with higher MA concentrations at home.

CONCLUSIONS

Spreading of MA from LAW's workplace to their home environment takes place, especially among LAWs involved in cleaning tasks.

Occupational Rhinitis

There is convincing evidence that tight relationships between the upper and lower airways also apply to the workplace context. Most patients with occupational asthma (OA) also suffer from occupational rhinitis (OR), although OR is 2 to 3 times more common than OA. OR most often precedes the development of OA, especially when high-molecular-weight protein agents are involved, and longitudinal cohort studies have confirmed that OR is associated with an increased risk for the development of OA. The level of exposure to sensitizing agents at the workplace is the most important determinant for the development of IgE-mediated sensitization and OR. Atopy is a risk factor for the development of IgE-mediated sensitization only to high-molecular-weight agents. In workers with work-related rhinitis symptoms, documentation of IgE-mediated sensitization to a workplace agent via skin prick testing or serum specific IgE confirms a diagnosis of probable OR, whereas specific nasal provocation testing in the laboratory remains the reference method to establish a definite diagnosis of OR. Complete avoidance of exposure to the causal agent is the most effective therapeutic option for controlling work-related nasal symptoms and preventing the development of OA. If complete elimination of exposure is expected to induce meaningful adverse socioeconomic consequences, reduction of exposure can be considered as an alternative approach, but it is important to consider the individual risk factors for the development of OA to implement a more personalized management of OR.

Understanding of the Molecular Mechanisms of Allergy

The prevalence of allergic disease has dramatically increased over the past 30 years in Westernized countries. It is unlikely that the rapid increase in the prevalence of allergic disease is the result of genetic changes, which highlights the importance of environmental factors in the development of allergic disease. The "hygiene hypothesis" was put forward in 1989 and focused attention on the notion that exposure to microbes and their products in early life can modify the risk for development of allergic disease. Infections were thought to polarize the immunological response toward a Th2-mediated immune response causing allergic disease. However, it is likely that the Th1/Th2 imbalance is too simplistic to explain the increased prevalence of allergic disease. Current research is focusing on understanding the role of T-regulatory cells in inducing a state of tolerance and the resulting modified Th2 response observed in natural and induced tolerance.

Laboratory animal allergy is preventable in modern research facilities

BACKGROUND

Historical data suggest 15% of laboratory animal workers develop IgE sensitisation and 10% symptoms of laboratory animal allergy (LAA), including occupational asthma. Individually ventilated cages (IVCs) are replacing conventional open cages; we sought to evaluate their impact on the development of LAA.

METHODS

We surveyed 750 laboratory animal workers and measured airborne Mus m 1 (mouse allergen) levels in seven UK institutions. We compared the prevalence of sensitisation to mouse proteins (by specific IgE assay or skin prick test) and of work-related allergic symptoms in IVC-only and open cage units.

RESULTS

Full-shift Mus m 1 levels were lower in IVC than open cage units (geometric mean 1.00 (95% CI 0.73-1.36) versus 8.35 (95% CI 6.97-9.95) ng·m^-3; p<0.001), but varied eight-fold across the IVC units (geometric mean range 0.33-4.12 ng·m^-3). Primary analyses on data from 216 participants with ≤3 years exposure to mice revealed a lower prevalence of sensitisation in those working in IVC units compared with conventional cage units (2.4% (n=2) versus 9.8% (n=13); p=0.052). Sensitisation in IVC units varied from 0% to 12.5%; the use of fitted respiratory protection was less common in IVC units where prevalence of sensitisation was higher. Work-related allergy symptoms were more frequently reported by mouse-sensitised individuals (46.7% versus 10.9%; p<0.001) and only by those working in open cage units.

CONCLUSION

In contemporary practice, LAA is now largely preventable with the use of IVC systems and the judicious use of appropriate respiratory protection.

Measurement of Specific IgG Anti-Fel d 1 Antibodies

There is currently considerable interest in the role of specific IgG antibodies in allergy. Several studies suggest that specific IgG antibodies may play a protective role in allergy. Successful immunotherapy is associated with increases in allergen-specific IgG antibodies which correlate with clinical outcome. Other studies have identified an inverse relationship between exposure to cat and sensitization, which was associated with high-titer-specific IgG and IgG₄. This immune response was described as a modified Th2 response, since both IgE and IgG₄ require Th2 cytokine IL-4 for their production. A modified Th2 response was described with laboratory animal allergy, where there was almost a twofold reduction in the risk of developing work-related chest symptoms.In this chapter, we review the major factors to be considered in the development of an ELISA for the determination of specific IgG and IgG₄ antibodies.

BSACI guideline for the diagnosis and management of allergic and non-allergic rhinitis (Revised Edition 2017; First edition 2007)

This is an updated guideline for the diagnosis and management of allergic and non-allergic rhinitis, first published in 2007. It was produced by the Standards of Care Committee of the British Society of Allergy and Clinical Immunology, using accredited methods. Allergic rhinitis is common and affects 10-15% of children and 26% of adults in the UK, it affects quality of life, school and work attendance, and is a risk factor for development of asthma. Allergic rhinitis is diagnosed by history and examination, supported by specific allergy tests. Topical nasal corticosteroids are the treatment of choice for moderate to severe disease. Combination therapy with intranasal corticosteroid plus intranasal antihistamine is more effective than either alone and provides second line treatment for those with rhinitis poorly controlled on monotherapy. Immunotherapy is highly effective when the specific allergen is the responsible driver for the symptoms. Treatment of rhinitis is associated with benefits for asthma. Non-allergic rhinitis also is a risk factor for the development of asthma and may be eosinophilic and steroid-responsive or neurogenic and non- inflammatory. Non-allergic rhinitis may be a presenting complaint for systemic disorders such as granulomatous or eosinophilic polyangiitis, and sarcoidoisis. Infective rhinitis can be caused by viruses, and less commonly by bacteria, fungi and protozoa.

Laboratory animal allergy: a new world

PURPOSE OF REVIEW

In recent years there has been a dramatic shift in the world of animal research whereby genetically modified mice have largely supplanted rats, and individually ventilated cages have been introduced to house delicate experimental animals in place of traditional open cages. Although laboratory animal allergy remains an important cause of occupational asthma, the risks associated with contemporary practice and consequently the opportunities for primary and secondary prevention are largely unknown.

RECENT FINDINGS

Although there is clear confirmation of a widespread increase in animal experiments using mice, the evidence-base on the associated risks has lagged. Individually ventilated cages reduce ambient levels of mouse urinary protein in air but task-based exposures are unquantified. Immunological techniques to identify sensitization to mouse proteins are poorly standardized. The available evidence suggests that modern practices are, in most cases, associated with a reduced incidence of animal sensitization.

SUMMARY

There is a paucity of data to inform evidence-based practice in methods to control the incidence of laboratory animal allergy under the prevailing research environment; a better understanding of the relationship between exposures and outcome is urgently needed. As exposures decline, the relative importance of individual susceptibility will become prominent.

Occupational Rhinitis Revisited: Emphasis on the Risk Factors in Saudi Industry

The European Academy of Allergy and Clinical Immunology (EAACI) Task Force defines occupational rhinitis (OR) as "an inflammatory disease of the nose, which is characterized by intermittent or persistent symptoms (i.e., nasal congestion, sneezing, rhinorrea, itching), and/or variable nasal airflow limitation and/or hypersecretion arising out of causes and conditions attributable to a particular work environment and not to stimuli encountered outside the workplace." The objectives of this review are to highlight the causes of OR in industrial settings in Saudi Arabia in order to alert primary healthcare physicians and other healthcare providers of the importance of diagnosing and managing OR to prevent further complications and present to the General Organization for Social Insurance (GOSI) evidence of the existence of OR in Saudi industrial sector. The literature search yielded no publications from Saudi Arabia that have investigated the prevalence of OR, but it is expected to be high judging from the high prevalence of allergic rhinitis in the country. The occupational groups that are at risk of developing OR include workers in the petrochemical industry, healthcare personnel, livestock and bird breeders, bakers, farmers, housewives and other occupations all of which are present in Saudi Arabia. Clinic and industry based research within Saudi Arabia is recommended to determine the prevalence of OR and to alert healthcare providers to suspect OR in all symptomatic working adults, including housewives and domestic helpers. Use of EAACI algorithm for the diagnosis and management of this condition will help to manage the condition and prevent the deterioration and further complications. Furthermore, diagnosis using internationally recognized guidelines and the results of the suggested epidemiologic surveys may convince GOSI to recognize OR as an occupational disease.

Career Advice for Young Allergy Patients

BACKGROUND

One-third of all young persons entering the work force have a history of atopic disease. Occupationally induced allergy and asthma generally arise in the first few months on the job, while pre-existing symptoms tend to worsen. Young persons with a history of an atopic disease should receive evidence-based advice before choosing a career.

METHODS

We systematically searched PubMed for cohort studies investigating the new onset of asthma, rhinitis, or hand eczema among job trainees from before the start of training and onward into the first few years on the job. The search revealed 514 articles; we read their abstracts and selected 85 full-text articles for further analysis. 24 of these met the inclusion criteria.

RESULTS

According to present evidence, atopy and a history of allergic disease (allergic rhinitis, atopic dermatitis) are the main risk factors for occupationally induced disease. The predictive value of a personal history of allergic diseases for the later development of an occupationally induced disease varies from 9% to 64% in the studies we analyzed. It follows that only young people with severe asthma or severe atopic eczema should be advised against choosing a job that is associated with a high risk of allergy, e.g., hairdressing or working with laboratory animals. Young people with a history of other atopic diseases should be counseled about their individual risk profile.

CONCLUSION

In view of the relatively poor predictive value of pre-existing atopic disease, secondary prevention is particularly important. This includes frequent medical follow-up of the course of symptoms over the first few years on the job. If sensitization or allergic symptoms arise, it should be carefully considered whether exposure reduction will enable the apprentice to stay on the job.

Laboratory Animal Allergy in the Modern Era

Laboratory animal workers face a high risk of developing laboratory animal allergy as a consequence of inhaling animal proteins at work; this has serious consequences for their health and future employment. Exposure to animal allergen remains to be the greatest risk factor although the relationship is complex, with attenuation at high allergen exposure. Recent evidence suggests that this may be due to a form of natural immunotolerance. Furthermore, the pattern of exposure to allergen may also be important in determining whether an allergic or a tolerant immune response is initiated. Risk associated with specific tasks in the laboratory need to be determined to provide evidence to devise a code of best practice for working within modern laboratory animal facilities. Recent evidence suggests that members of lipocalin allergens, such as Mus m 1, may act as immunomodulatory proteins, triggering innate immune receptors through toll-like receptors and promoting airway laboratory animal allergy. This highlights the need to understand the relationship between endotoxin, animal allergen and development of laboratory animal allergy to provide a safe working environment for all laboratory animal workers.

Work-related allergies to storage mites in Parma (Italy) ham workers

OBJECTIVES

To investigate the role of storage mites in the development of allergic diseases among ham production workers, and to search for early alterations in lung function tests and early inflammation markers in exhaled air. Respiratory allergies due to storage mites have been reported in people with various occupations but, although such mites are unavoidable when curing ham, there are no published data concerning ham production workers.

SETTING

Secondary care.

DESIGN

Experimental cross-sectional study.

PARTICIPANTS

220 participants (110 ham production workers and 110 controls) were recruited.

PRIMARY AND SECONDARY OUTCOME MEASURES

Workers answered a medical questionnaire, and underwent spirometry and fraction of exhaled nitric oxide at 50 mL/s (FeNO₅₀) measurements. Those with allergic symptoms also underwent skin prick tests to determine their sensitisation to airborne allergens. A methacholine test was performed in symptomatic participants when spirometry was normal to assess airways hyper-responsiveness.

RESULTS

Symptomatic storage mite sensitisation was observed in 16 workers (14.5%) (rhinoconjunctivitis in 15 (63%) and asthma in (4%)) and 2 controls (1.8%; p=0.001). Higher FeNO₅₀ values in exposed symptomatic workers compared with healthy control participants (34.65±7.49 vs 13.29±4.29 ppb; p<0.001) suggested bronchial and nasal involvement, although their lung function parameters were normal. Regardless of exposure, a FeNO₅₀ value of 22.5 ppb seems to be 100% sensitive and 99.4% specific in distinguishing allergic and non-allergic participants. Multivariate analysis of FeNO₅₀ values in the symptomatic participants showed that they were positively influenced by IgE-mediated allergy (p=0.001) and reported symptom severity (p=0.041), and negatively by smoking status (p=0.049).

CONCLUSIONS

Ham processing workers, as well as workers involved in any meat processing work that includes curing, should be informed about the occupational risk of sensitisation to mites.

Rat-specific IgG and IgG₄ antibodies associated with inhibition of IgE-allergen complex binding in laboratory animal workers

OBJECTIVES

The relationship between exposure to rodent allergens and laboratory animal allergy is complex; at highest allergen exposures there is an attenuation of sensitisation and symptoms which are associated with increased levels of rat-specific immunoglobulin (Ig)G and IgG4 antibodies. We set out to examine whether the increased levels of rat-specific IgG and IgG4 antibodies that we have previously observed at high allergen exposure in our cohort of laboratory animal workers play a functional role through blockage of the binding of IgE-allergen complex binding to CD23 receptors on B cells.

METHODS

Cross-sectional survey of laboratory animal workers (n=776) in six UK pharmaceutical companies were surveyed. IgE-allergen complex binding to B cells was measured in 703 (97.9%) eligible employees; their exposure was categorised by either job group or number of rats handled daily.

RESULTS

We observed a significant decrease in IgE-allergen complex binding to B cells with increasing quartiles of both rat-specific IgG and IgG4 antibodies (p<0.001). IgE-allergen complex binding to B cells was lower in workers with high allergen exposure, and significantly so (p=0.033) in the subgroup with highest exposures but no work-related chest symptoms.

CONCLUSIONS

These findings demonstrate a functional role for rat-specific IgG/G4 antibodies in laboratory animal workers, similar to that observed in patients treated with high dose immunotherapy who become clinically tolerant, suggesting a potential explanation for the attenuation of risk at highest allergen exposures.

Prevalence of occupational allergy in medical researchers exposed to laboratory animals

Allergy to laboratory animals is a well known occupational hazard and remains a health concern for individuals in contact with lab animals. This study evaluates the prevalence of allergy symptoms among medical researchers exposed to laboratory animals. We analyzed data from a cross-sectional survey, involving subjects (n=169, 21-59 yr), working in Kochi Medical School, Japan. They were asked to fill out a questionnaire to evaluate symptoms related to contact with laboratory animals. The overall response rate was 86.2%. The prevalence of laboratory animal allergy was 17.6%. The symptoms most reported were allergic rhino-conjunctivitis and asthma. A small number of the subjects received education on the allergy issue and 62.5% of subjects with an allergy to laboratory animals claimed to have atopy. Protection from animal allergens should be a high priority for institutions using lab animals; providing continuous education to animal handlers would be meaningful to reduce and control exposure.

The characteristics, treatment and prevention of laboratory animal allergy

Laboratory animal allergy (LAA) is a pervasive problem that affects up to one-third of laboratory animal personnel. An immediate hypersensitivity reaction can be triggered by contact with antigens present in urine, hair, dander and saliva of laboratory animals. The authors provide an overview of the epidemiology, triggering mechanisms, diagnosis, treatment and risk factors of LAA. They also discuss primary and secondary prevention measures that can be taken to reduce LAA morbidity and to allow personnel suffering from LAA to safely continue to do their jobs.

Occupational airborne exposure, specific sensitization and the atopic status: evidence of a complex interrelationship

Background

We have investigated the relationship between atopic status and long-term occupational exposure to latex proteins or methyl diethyl diisocyanate (MDI) as high and low molecular weight asthma-inducing agents, respectively.

Methods

This study is based on retrospective analyses of two groups of symptomatic outpatients: 184 healthcare workers with latex exposure and 156 workers with isocyanate (MDI) exposure. We analysed atopic and non-atopic subgroups according to exposure duration and the frequencies of specific sensitization.

Results

45% of the healthcare subgroup specifically sensitized to latex were atopic, whereas in the non-sensitized healthcare subgroup only 26% were atopic. On the other hand, subjects specifically sensitized to MDI were rarely atopic (only 15%), whereas in the subgroup non-sensitized to MDI atopy was present in 38%. After prolonged durations of exposure, the proportion of atopics was further elevated in most healthcare subgroups but it decreased in the MDI-exposed subjects.

Conclusions

We hypothesize that latex proteins as sensitizing agents might promote the development of atopy, whereas exposure to the low molecular weight MDI might inhibit the atopic status.

Sensitization and symptoms associated with soybean exposure in processing plants in South Africa

BACKGROUND

Following the results of a previous study that highlighted the potential for significant levels of dust exposure in South African soybean processing plants, a clinical investigation was undertaken to study the respiratory health of workers in this industry.

METHODS

Workers from three soybean-processing plants were studied with a respiratory questionnaire and estimation of atopy and specific soybean IgE.

RESULTS

A total of 144 of the 181 (79.6% participation rate) plant employees completed the questionnaire and 136 (75.1%) gave blood samples for analysis of specific IgE. There was a significant association between work-related chest tightness (OR 4.0 [95% CI 1.3-12.6]), work-related nasal symptoms (OR 4.3 [95% CI 1.3-14.6]) and cough or chest tightness after handling soybean (OR 3.6 [95% CI 1.1-11.6]) and soybean sensitization. There was a significant association between current exposure to dust during soybean off-loading and "flu-like" illness (OR 2.7 [95% CI 1.0-7.2]), and cough or chest tightness after such work (OR 7.4 [95% CI 2.4-23.6]). The strongest predictor of work related nasal symptoms was sensitization to soybean, the latter strongly predicted by the presence of atopy (OR 34.7 [95% CI 6.6-182.5]).

CONCLUSIONS

Exposure and sensitization to soybean were associated with the presence of work related symptoms, including flu-like symptoms, cough, chest tightness, and nasal symptoms. The aetiology of these symptoms and more particularly the best intervention strategies require more detailed investigation.

EAACI position paper: prevention of work-related respiratory allergies among pre-apprentices or apprentices and young workers

Apprenticeship is a period of increased risk of developing work-related respiratory allergic diseases. There is a need for documents to provide appropriate professional advice to young adults aiming to reduce unsuitable job choices and prevent impairment from their careers. The present document is the result of a consensus reached by a panel of experts from European and non-European countries addressed to allergologists, pneumologists, occupational physicians, primary care physicians, and other specialists interested in this field, which aims to reduce work-related respiratory allergies (rhinoconjunctivitis and asthma) among allergic or nonallergic apprentices and other young adults entering the workforce. The main objective of the document is to issue consensus suggestions for good clinical practice based on existing scientific evidence and the expertise of a panel of physicians.

Both the variability and level of mouse allergen exposure influence the phenotype of the immune response in workers at a mouse facility

BACKGROUND

The role of natural aeroallergen exposure in modulating allergen-specific immune responses is not well understood.

OBJECTIVE

We sought to examine relationships between mouse allergen exposure and mouse-specific immune responses.

METHODS

New employees (n = 179) at a mouse facility underwent repeated assessment of mouse allergen exposure, skin prick tests (SPTs), and measurement of mouse-specific IgG levels. Relationships between the mean level of exposure, variability of exposure (calculated as log deviation), and time to development of immunologic outcomes were examined by using Cox proportional hazards models.

RESULTS

By 24 months, 32 (23%) participants had experienced a positive SPT response, and 10 (8%) had mouse-specific IgG₄. The incidence of a positive SPT response increased as levels of exposure increased from low to moderate, peaking at 1.2 ng/m³, and decreased beyond this point (P = .04). The more variable the exposure was across visits, the lower the incidence of a positive SPT response (hazard ratio [HR], 0.17; 95% CI, 0.07-0.41). Variability of exposure was an independent predictor of a positive SPT response in a model that included both exposure metrics. In contrast, the incidence of mouse-specific IgG₄ increased with increasing levels of mouse allergen exposure (HR, 2.9; 95% CI, 1.4-6.0), and there was evidence of a higher risk of mouse-specific IgG₄ with greater variability of exposure (HR, 6.3; 95% CI, 0.4-95.2).

CONCLUSION

Both the level and variability of mouse allergen exposure influence the humoral immune response, with specific patterns of exposure associated with specific immunophenotypes. Exposure variability might be a more important predictor of a positive SPT response, whereas the average exposure level might be a more important predictor of mouse-specific IgG₄.

Occupational asthma: etiologies and risk factors

The purpose of this article is to critically review the available evidence pertaining to occupational, environmental, and individual factors that can affect the development of occupational asthma (OA). Increasing evidence suggests that exploration of the intrinsic characteristics of OA-causing agents and associated structure-activity relationships offers promising avenues for quantifying the sensitizing potential of agents that are introduced in the workplace. The intensity of exposure to sensitizing agents has been identified as the most important environmental risk factor for OA and should remain the cornerstone for primary prevention strategies. The role of other environmental co-factors (e.g., non-respiratory routes of exposure and concomitant exposure to cigarette smoke and other pollutants) remains to be further delineated. There is convincing evidence that atopy is an important individual risk factor for OA induced by high-molecular-weight agents. There is some evidence that genetic factors, such as leukocyte antigen class II alleles, are associated with an increased risk of OA; however, the role of genetic susceptibility factors is likely to be obscured by complex gene-environment interactions. OA, as well as asthma in general, is a complex disease that results from multiple interactions between environmental factors and host susceptibilities. Determining these interactions is a crucial step towards implementing optimal prevention policies.

Occupational exposure to laboratory animals causing a severe exacerbation of atopic eczema

A 24-year-old man with a long history of severe atopic eczema presented with a marked exacerbation requiring hospital admission. It emerged that his occupation as an animal house technician required him to work closely with laboratory animals, particularly mice and rats. Radioallergosorbent tests to mice allergens were markedly elevated. Avoidance of animal work, in conjunction with medical treatment, resulted in a marked improvement of his eczema.

Dynamics in cytokine responses during the development of occupational sensitization to rats

BACKGROUND

Occupational allergy forms an attractive model to study the development of allergic responses, as in some occupations it has a high incidence and develops quickly. In a cohort of starting laboratory animal workers, we previously found 20% sensitization to animal allergens within 2 years.

METHODS

We compared cellular responses of incident laboratory animal workers who developed rat-specific sensitization (cases, n = 18) during 2 years of follow-up to control animal workers matched for atopic status but without sensitization after follow-up (controls, n = 18). Practically, this is a case-control study, nested within the cohort. Rat-specific IgE antibodies were measured in sera, and allergen-specific and nonspecific cytokine responses were measured in whole blood and in isolated peripheral blood mononuclear cells.

RESULTS

Self-reported allergic symptoms were related to the presence of rat-specific IgE (P ≤ 0.01). Cases developed a rat allergen-specific interleukin (IL)-4 response during sensitization, while controls did not show an increased IL-4 response (at visit D: 33 vs 5 IL-4 producing cells/10(6) cells, P < 0.001). The IL-4 response was related to the levels of rat-specific IgE in cases (visit D: rho = 0.706, P < 0.001). By contrast, allergen-specific IL-10 and interferon γ (IFNγ) responses as well as nonspecific cytokine responses were comparable between cases and controls.

CONCLUSION

This study is the first to show the development of an allergen-specific IL-4 response in adult human subjects during allergen-specific sensitization. This IL-4 response was quantitatively associated with the development of the specific IgE antibodies. Allergen-specific or nonspecific IL-10 and IFNγ responses showed no protective effect on the development of allergic sensitization.

Allergy to rodents: an update

Allergy to rodents in the workplace is an important occupational health problem affecting research, pharmaceutical and toxicological sectors and can have a serious impact on employees working in this area. Despite measures to reduce aeroallergen exposures to rodents in the workplace, there are few signs that this occupational health problem is declining. Rodent allergens are well characterized and exposure-response relationships have been demonstrated to be complex. More recently, the importance of rodent allergens outside of the workplace has been demonstrated in several studies of individuals with asthma. This review focuses on rodent allergy both in the workplace and in the home and examines the complex exposure-response relationships between allergen exposure and sensitization and asthma. Risk factors for rodent allergy and mechanisms of tolerance to rodent allergens are discussed.

Increase in exhaled nitric oxide is associated with bronchial hyperresponsiveness among apprentices

RATIONALE

Airway inflammation is a hallmark of asthma. Several studies have validated the use of the fractional concentration of exhaled nitric oxide (Fe(NO)) as a surrogate marker of airway inflammation in asthma.

OBJECTIVES

We examined how the change in Fe(NO) levels, since the beginning of occupational exposure, could be associated with the incidence of bronchial hyperresponsiveness (BHR) among baker, pastry maker, and hairdresser apprentices during their 2-year training.

METHODS

A standardized questionnaire was administered; skin prick tests for common and specific occupational allergens were done; methacholine challenge and measurement of Fe(NO) were performed 6, 12, and 15 months after the first examination.

MEASUREMENTS AND MAIN RESULTS

Of 441 apprentices initially included, 351 completed the study. The increase in Fe(NO), since the beginning of exposure, was associated with the incidence of BHR (odds ratio, 2.00 [95% confidence interval, 1.21-3.32] per unit increase in log parts per billion) both in atopic and nonatopic subjects. The average increase in Fe(NO) was similar in atopic and nonatopic subjects and was unrelated to past or current smoking habits, sex, or training track. Atopy in bakers/pastry makers and sensitization to alkaline persulfates in hairdressers were also independently associated with the incidence of BHR. BHR occurred sooner among bakers/pastry makers than among hairdressers, but its incidence leveled off later.

CONCLUSIONS

Our results suggest that measurement of Fe(NO), a simple and reproducible test, could be useful in the screening of BHR in workers newly exposed to agents known to cause occupational asthma.

Occupational asthma: risk factors, diagnosis and preventive measures

In adulthood, new or recurrent asthma is caused by work in approximately 10% of cases. The term occupational asthma is reserved for those cases arising from respiratory hypersensitivity to a specific workplace agent; in others (work-exacerbated asthma) the mechanism is of nonspecific airway irritation on a background of bronchial hyper-reactivity. Some 300 workplace agents are capable of inducing asthma de novo; fortunately, most cases are attributed to a much smaller number to which exposure occurs in a few high-risk occupations. Exposure level is the most important remediable risk factor; the factors governing individual susceptibility are poorly understood. Diagnosis is generally straightforward. Management is rarely pharmacologic and often difficult since the diagnosis incurs important employment and other social consequences.

Occupational and environmental lung disease: occupational asthma

Occupational exposures cause 10-15% of new-onset asthma in adults, and that represents a considerable health and economic burden. Exposure to many causative agents is now well controlled but workplace practices are constantly evolving and new hazards being introduced. Overall, there is no good evidence that the incidence of occupational asthma is decreasing. Evidence-based guidelines such as those published by the British Occupational Health research Foundation and Standards of Care documents should help raise awareness of the problem and improve management. Key targets include the control of occupational exposures, a high index of suspicion in any adult with new onset asthma, and early detailed investigation.

Dual sensitization to rat and mouse urinary allergens reflects cross-reactive molecules rather than atopy

BACKGROUND

Sensitization to rats and mice can develop in laboratory animal workers exposed to only one species. Reasons for this dual sensitization are unclear but may reflect a genetic predisposition to developing allergy (atopy) or alternatively cross-reactivity between rat and mouse urinary allergens. We examined cross-reactivity between rat and mouse urine and the effect atopy has on dual sensitization in laboratory animal workers.

METHODS

In a cross-sectional study the frequency of sensitization to rat and/or mouse was analysed in 498 employees exposed to both rat and mouse at work and 220 to rat only. RAST inhibitions, western blots and blot inhibitions were carried out on a subset of five individuals to assess cross-reactivity.

RESULTS

Fourteen per cent of workers were sensitized to rats and 9% to mouse. Over half (62%) of rat sensitized individuals were also mouse sensitized and the majority (91%) of mouse sensitized individuals were also rat sensitized. IgE cross-reactivity was demonstrated between rat and mouse urine using RAST inhibitions. Rates of atopy did not differ between rat only sensitized individuals compared with those sensitized to both species. Sensitization to cats and rabbits was more common amongst those with dual sensitization.

CONCLUSIONS

Dual sensitization to rat and mouse reflects IgE cross-reactivity rather than atopy. Individuals with dual sensitization are more likely to be sensitized to other animal allergens. These findings will have implications for individuals working with only one rodent species who develop sensitization and symptoms to be aware of the potential for allergy to other species.

EAACI position paper on occupational rhinitis

The present document is the result of a consensus reached by a panel of experts from European and non-European countries on Occupational Rhinitis (OR), a disease of emerging relevance which has received little attention in comparison to occupational asthma. The document covers the main items of OR including epidemiology, diagnosis, management, socio-economic impact, preventive strategies and medicolegal issues. An operational definition and classification of OR tailored on that of occupational asthma, as well as a diagnostic algorithm based on steps allowing for different levels of diagnostic evidence are proposed. The needs for future research are pointed out. Key messages are issued for each item.

Exposure-response in occupational allergy

PURPOSE OF REVIEW

This review examines the relationship between exposure to workplace allergens and the risk of developing occupational allergy.

RECENT FINDINGS

Evidence suggests that the risk of developing occupational allergy increases with allergen exposure; however, with some occupational allergens, this exposure-response relationship is more complex. In laboratory animal workers, the risk of developing occupational allergy increases with exposure, except at high allergen exposure when there is a reduction in sensitization. This attenuation of specific immunoglobulin E antibody is associated with increased specific immunoglobulin G4 antibodies, which are likely to play a protective role, leading to a form of natural tolerance. Exposure-response relationships are also very dependent on the genetic susceptibility of the individual. The interaction between genes, occupational allergens and other cofactors in the environment, such as endotoxin, are also important risk factors in the development of sensitization and asthma.

SUMMARY

Occupational allergy provides a good opportunity to understand the complex relationships between exposure to allergens in the workplace, interaction with genes and the coexposures with other factors in the working environment and the increased risk of developing occupational allergy.

Association of Toll-like receptor 4 alleles with symptoms and sensitization to laboratory animals

BACKGROUND

Researchers and technicians working with laboratory animals (LAs) are exposed to animal allergen and endotoxin, which can interact to potentiate or inhibit symptoms or allergic responses. We hypothesized that functional genetic variants of Toll-like receptor 4 (TLR4), a key surface receptor for endotoxin, interface between worker and workplace and affect animal sensitization, symptoms, or both.

OBJECTIVE

We sought to determine whether TLR4/8551 variants alter the risk for LA sensitization, symptoms, or both.

METHODS

Three hundred thirty-five researchers, 195 of whom worked with animals, completed questions on workplace practices and symptoms and underwent skin prick tests or RASTs to common and animal allergens. Real-time PCR assessed TLR4/8551 and TLR4/8851 variants. Nominal logistic regression was used to analyze the contribution of demographic, exposure, and genetic variables to outcomes of interest.

RESULTS

Twenty-one percent of workers were LA sensitized, and 29% reported 1 or more symptoms to LAs. The TLR4/8551 G variant, which is less responsive to endotoxin, was detected in 9% and in linkage disequilibrium with the TLR4/8851 T allele. The G variant significantly associated with atopy and LA sensitization. Workers with the G variant spent significantly longer hours in high endotoxin/animal allergen tasks compared with those with the AA variant, which is perhaps less affected by endotoxin exposures. In multivariate analyses the G variant and longer animal research hours increased the risk of LA sensitization. Job tasks and LA sensitization, but not TLR4 variants, were predictors of LA-induced symptoms.

CONCLUSION

Workers with TLR4 variants that reduce responsiveness to endotoxin have higher risks for LA and other allergen sensitization but spend longer hours in tasks with high endotoxin and animal allergen exposures.

Measurement of specific IgG anti-Fel d 1 antibodies

There is currently considerable interest in the role of specific IgG antibodies in allergy. Several studies suggest that specific IgG antibodies may play a protective role in allergy. Successful immunotherapy is associated with increases in allergen-specific IgG antibodies which correlate with clinical outcome. Other studies have identified an inverse relationship between exposure to cat and sensitization, which was associated with high titer specific IgG and IgG(4). This immune response was described as a modified Th2 response, because both IgE and IgG(4) require Th2 cytokine IL-4 for their production. A modified Th2 response was described with laboratory animal allergy, where there was almost a twofold reduction in the risk of developing work-related chest symptoms.In this chapter, we review the major factors to be considered in the development of an ELISA for the determination of specific IgG and IgG(4) antibodies.

Occupational rhinitis

The present document is the result of a consensus reached by a panel of experts from European and nonEuropean countries on Occupational Rhinitis (OR), a disease of emerging relevance, which has received little attention in comparison to occupational asthma. The document covers the main items of OR including epidemiology, diagnosis, management, socio-economic impact, preventive strategies and medicolegal issues. An operational definition and classification of OR tailored to that of occupational asthma, as well as a diagnostic algorithm based on steps allowing different levels of diagnostic evidence, are proposed. The needs for future research are pointed out. Key messages are issued for each item.

Have the prevalence and incidence of occupational asthma and rhinitis because of laboratory animals declined in the last 25 years?

BACKGROUND

Data for time trends in the prevalence of occupational asthma (OA) and rhinitis (OR) are not known.

OBJECTIVE

To investigate the prevalence and incidence of OA and OR over time.

METHODS

We chose to review studies on the prevalence and incidence of OA and OR due to laboratory animals (LA) as a marker of changing OA and OR patterns over time and analysed 15 cross-sectional and 4 longitudinal studies published from 1980 to 2006.

RESULTS

The estimated prevalence of OA, defined as work-related chest symptoms (WRCS), declined from 8.2% in 1976 to 4.2% in 2001 (P < 0.005). When defined by WRCS and positive skin prick test (SPT) to LA, the estimated prevalence of OA was 6.7% in 1977 and 2.9% in 1999 (P < 0.02). The prevalence of OR, defined by WRNS or WRNS and SPT to LA, was not related to study date but was inversely associated with mean exposure duration. In four longitudinal studies no clear trend emerged over time.

CONCLUSIONS

This review suggests a trend toward a progressive decline in the prevalence of occupational asthma due to laboratory animals, which may be due to the reduction of exposure since the early 1980s. A further reduction of exposure is needed to prevent the onset of occupational rhinitis.

Is there a need for special preventive medical check-ups in employees exposed to experimental animal dust?

OBJECTIVE

Due to new legal requirements in Germany, the employer must request preventive medical check-ups for activities involving exposure to dust from experimental animals in the rooms in which the animals are kept. The objective is to report our first experiences with these medical check-ups in the context of academic research.

METHODS

The check-ups were carried out since November 2005 and comprised a questionnaire and a medical examination, including a pulmonary function test with whole-body plethysmography. Respiratory, nasal and ocular symptoms related to occupational exposure to animals were documented. Participation in skin prick tests (ubiquitous inhalation allergens and laboratory animal allergens), a bronchial provocation test with methacholine, and serological examinations for total IgE and specific IgE antibodies was voluntary.

RESULTS

Data on 132 persons are presented. One hundred and six of these had already been exposed for at least 1 year. Main complaints at the workplace were sneezing and runny nose. Ocular symptoms and bronchial asthma were reported infrequently. The development of at least one of these symptoms occurred in 34% of employees with an exposure of at least 1 year. If the weekly exposure duration was at least 5 h, the proportion of employees with complaints rose to 44.9%. In employees occupationally exposed to mice and rats, work-related complaints occurred in 33.7 and 37.8%, respectively, and sensitisation rates were 12.7 and 16.3%, respectively. Employees with and without complaints differed in history of allergic symptoms, and workplace safety measures.

CONCLUSIONS

In employees with occupational contact with laboratory animal dust, the frequency of complaints was high. The results confirm the necessity of regular medical check-ups for employees with contact with laboratory animal dust. Nevertheless, the medical check-ups must be part of a prevention strategy including education, engineering controls, administrative controls, use of personal protective equipment and vocational integration.

Making the diagnosis of occupational asthma: when to suspect it and what to do

Although most adult patients seen by a clinician are employed, medical school curricula and residency training rarely cover occupational exposures and resultant diseases, even common ones that are encountered in a typical medical practice. This primer on occupational asthma is intended for the primary care clinician to provide the essential tools to diagnose and treat airways disease in the workplace. Using a case vignette format, we review the basic approach to suspecting and establishing a diagnosis of occupational asthma and address the thornier question of what to do about it. After reviewing this primer, the reader will be able to routinely include occupational asthma as part of the differential diagnoses in the adult patient with new or worsened asthma.

BSACI guidelines for the management of allergic and non-allergic rhinitis

This guidance for the management of patients with allergic and non‐allergic rhinitis has been prepared by the Standards of Care Committee (SOCC) of the British Society for Allergy and Clinical Immunology (BSACI). The guideline is based on evidence as well as on expert opinion and is for use by both adult physicians and paediatricians practicing in allergy. The recommendations are evidence graded. During the development of these guidelines, all BSACI members were included in the consultation process using a web‐based system. Their comments and suggestions were carefully considered by the SOCC. Where evidence was lacking, consensus was reached by the experts on the committee. Included in this guideline are clinical classification of rhinitis, aetiology, diagnosis, investigations and management including subcutaneous and sublingual immunotherapy. There are also special sections for children, co‐morbid associations and pregnancy. Finally, we have made recommendations for potential areas of future research.

Rodent allergen in Los Angeles inner city homes of children with asthma

Recent studies have examined the presence of mouse allergen in inner city children with asthma. Researchers have found high levels of rodent allergen in homes sampled in the northeast and midwest United States, but there has been considerable variation between cities, and there have been few studies conducted in western states. We evaluated the frequency of rodent sightings and detectable mouse allergen and the housing conditions associated with these outcomes in inner city homes in Los Angeles. Two hundred and two families of school children, ages 6-16 living in inner city neighborhoods, participated in the study. Families were predominantly Latino (94%), and Spanish speaking (92%). At study entry, parents completed a home assessment questionnaire, and staff conducted a home evaluation and collected kitchen dust, which was analyzed for the presence of mouse allergen. Fifty-one percent of homes had detectable allergen in kitchen dust. All 33 families who reported the presence of rodents had detectable allergen in the home and were also more likely to have increased levels of allergen compared to those who did not report rodents. Unwashed dishes or food crumbs, lack of a working vacuum, and a caretaker report of a smoker in the home were all significantly associated with a greater risk of rodent sightings or detectable allergen (P<0.05). Detached homes were significantly more likely to have detectable allergen. The prevalence of allergen is common enough that it may have public health implications for asthmatic children, and detectable allergen was not routinely identified based on rodent sightings. Many of the predictors of rodent allergen are amenable to low-cost interventions that can be integrated with other measures to reduce exposure to indoor allergens.

[Epidemiology and etiologic agents of occupational asthma]

INTRODUCTION

Occupational asthma is, by definition, a disease that can be prevented through appropriate protective strategies. Epidemiological information is required to guide these interventions, and we here examine epidemiological data on the burden, causes, and risk factors for this condition.

STATE OF THE ART

Population-based surveys indicate that approximately 15% of adult asthma is attributable to the workplace environment. The most common occupational agents implicated include flour, isocyanates, latex, and persulphate salts. The occupations in which occupational asthma has been most commonly reported are bakers, spray painters, health-care workers, hairdressers, and cleaners. The level of exposure to sensitizing agents seems to be the most relevant risk factor. Atopy is a significant risk factor only for the development of sensitization to high molecular weight agents. The role of other individual determinants, such as genetic factors, has been less consistently established. Occupational asthma is associated with a substantial adverse impact on the employment and financial status of affected workers.

PERSPECTIVES

Methodological improvements are required in order to distinguish more accurately between occupational and work-exacerbated asthma. Further investigations of the effectiveness of primary and secondary preventive interventions are also needed.