IgE-sensitization to predatory mites and respiratory symptoms in Swedish greenhouse workers

High Prevalence of Sensitization to Mites and Insects in Greenhouses Using Biologic Pest Control

BACKGROUND

Mites and insects are widely used as biologic pest control in greenhouses. A few studies have reported sensitization to mites among greenhouse workers, but the prevalence of sensitization to pest control insects is not known.

OBJECTIVE

We aimed to determine the prevalence of IgE-mediated sensitization to pests and their control organisms in the population of exposed greenhouse workers and the relationship between sensitization and allergic symptoms.

METHODS

In a cross-sectional study, we interviewed 117 tomato and cucumber greenhouse workers from eight companies that use biologic pest control. Sensitization to nine organisms was assessed by serum-specific IgE measurement. We also measured fractional exhaled nitric oxide.

RESULTS

The prevalence of specific sensitization to pests and pest control organisms was 50%; to mites, 29%; and to insects, 46%. Of the individual species, Macrolophus pygmaeus insect sensitization had the highest prevalence (46%). Asthma symptoms were significantly associated with sensitization to pest and pest control organisms (odds ratio [OR] = 3.9; 95% confidence interval [CI], 1.2-12.5) and with a fractional exhaled nitric oxide level of 25 ppb or greater (OR = 4.8; 95% CI, 1.7-13.8), indicating eosinophilic airway inflammation. Southeast Asian origin was significantly associated with sensitization (OR = 5.1; 95% CI, 2.1-12.1) and rhinitis (OR = 2.8; 95% CI, 1.2-6.3).

CONCLUSIONS

Tomato and cucumber greenhouse workers were commonly sensitized to predatory insect M pygmaeus and pest control mites. Our findings stress the importance of surveilling and preventing work-related allergic diseases among greenhouse workers.

Landscape Plant Selection Criteria for the Allergic Patient

Patients with pollen-related allergies are concerned about the species within their landscape that provoke their symptoms. Allergists are often asked for guidance but few information sources are available to aid patients in the recognition of allergenic plants and strategies to avoid personal exposure to them. Landscaping and horticultural workers also have few reliable guidance references, and what is available usually extols the virtues of the plants rather than their negative features. The aim of this article was to provide the results of the Landscape Allergen Working Group that was formed by the AAAAI Aerobiology Committee, which aimed to fill these existing knowledge gaps and develop guidance on producing a low-allergenic landscape. Within the context that complete pollen avoidance is unrealistic, the workgroup introduces selection criteria, avoidance strategies, and guidance on low-allergenic plants that could be selected by patients to reduce the overall pollen burden in their landscape environment. Specific focus is placed on entomophilous plants, which require insects as dispersal vectors and generally produce lower quantities of pollen, compared with anemophilous (wind-pollinated) species. Other biological hazards that can be encountered while performing landscaping activities are additionally reviewed and avoidance methods presented with the aim of protecting gardeners, and workers in the landscape and horticulture industries. The guidance presented in this article will ultimately be a helpful resource for the allergist and assist in engaging patients who are seeking to reduce the burden of allergen in their landscape environment.

Epidemiology of spider mite sensitivity: a meta-analysis and systematic review

Background

Spider mites, including Tetranychus urticae, Panonychus citri, and Panonychus ulmi, are common pests in gardens, greenhouses, and orchards. Exposure, particularly occupational exposure, to these organisms may lead to the development of respiratory or contact allergies. However, the prevalence of sensitivity to spider mites is unclear.

Methods

We examined the literature to generate an estimate of the global prevalence of allergies to spider mites.

Results

Electronic databases were searched and twenty-three studies reporting the prevalence of sensitivity to spider mites (based on skin prick tests or IgE-based detection systems) in an aggregate total of 40,908 subjects were selected for analysis. The estimated overall rate of spider mite sensitivity was 22.9% (95% CI 19–26.8%). Heterogeneity was high and meta-regression analysis considering variables such as published year, country, number of study subjects, methods for allergen detection (skin prick test, ImmunoCAP, RAST testing, or intradermal test), and mite species revealed no single significant source. Twelve of the 23 studies reported rates of monosensitization (i.e., patients responsive to spider mites but no other tested allergen), yielding a global average of 7% (95% CI 5–9%), hence spider mites represent a unique source of allergens.

Conclusions

Spider mites are an important cause of allergic symptoms. However, the publication bias and heterogeneity evident in this study indicate that further trials using standardized detection methods are needed to determine the association of exposure and symptoms as well as the specific patient characteristics that influence developing spider mite sensitivity.

Occupational allergy to bell pepper pollen in greenhouses in the Netherlands, an 8-year follow-up study

BACKGROUND

Pollen from bell pepper plants cultivated in greenhouses are known to cause occupational allergic disease. A cross-sectional study among 472 bell pepper employees in 1999 estimated prevalences for sensitization to bell pepper pollen of 28% and for work-related allergic symptoms of 54%. There is scarce information on the incidence of work-related allergy and its risk factors. Aims of the present study were to estimate the cumulative incidence of work-related symptoms and sensitization to bell pepper pollen, and to determine risk factors for the onset of these symptoms and sensitization.

METHODS

Bell pepper employees who participated in a cross-sectional survey in 1999 were asked to take part in a follow-up study in 2007. Information on demographic characteristics, job characteristics and allergic symptoms was gathered by means of a questionnaire. Furthermore, skin tests were performed with a.o. bell pepper pollen.

RESULTS

In total, 280 of 472 employees were available for questionnaires and in 250 employees allergy tests were performed. During the 8-year follow-up, the cumulative incidence of sensitization to bell pepper pollen was 9% and of work-related rhinitis 19%. Atopy [odds ratio (OR) 5.60] and smoking (OR 3.53) were significantly associated with development of rhinitis. The cumulative incidence of work-related asthma symptoms was 8%. Again atopy (OR 5.03) and smoking (OR 11.85) were significant risk factors.

CONCLUSION

Cumulative incidences for sensitization to bell pepper pollen, work-related rhinitis and asthma symptoms were 9%, 19% and 8%, respectively. Atopy and smoking are risk factors for developing work-related symptoms among workers in bell pepper horticulture.

The New Zealand workforce survey II: occupational risk factors for asthma

INTRODUCTION

We conducted a cross-sectional population-based survey in New Zealand that collected information on work history, current workplace exposures, and selected health outcomes. We report here the findings on occupational risk factors for asthma symptoms.

METHODS

A random sample of men and women aged 20-64 years were selected from the New Zealand Electoral Roll and invited to take part in a telephone survey. Current asthma was defined as: (i) woken up by shortness of breath in the past 12 months; or (ii) an attack of asthma in the past 12 months; or (iii) currently taking asthma medication. Adult-onset asthma was defined as first attack of asthma at age 18 or over. Prevalence odds ratios (ORs) for all occupations were calculated using logistic regression adjusting for sex, age, smoking, and deprivation.

RESULTS

Totally, 2903 participants were included in the analyses. The prevalence of current asthma was 17% and the prevalence of adult-onset asthma was 9%. Prevalence ORs for current asthma were elevated for ever working as a printer [OR = 2.26; 95% confidence interval (CI) = 1.09-4.66], baker (OR = 1.98; 95% CI = 1.02-3.85), sawmill labourer (OR = 3.26; 95% CI = 1.05-10.16), metal processing plant operator (OR = 2.48; 95% CI = 1.22-5.05), and cleaner (OR = 1.60; 95% CI = 1.09-2.35). Excess risks of adult-onset asthma were also found for ever working as a printer, baker, and sawmill labourer as well as ever-working as a market-oriented animal producer (OR = 1.66; 95% CI = 1.14-2.41), and other agricultural worker (OR = 2.08; 95% CI = 1.03-4.20). A number of occupations not previously considered at high risk for asthma were also identified, including teachers and certain sales professionals.

CONCLUSION

This population-based study has confirmed findings of previous international studies showing elevated risks in a number of high-risk occupations. The strongest risks were consistently observed for printers, bakers, and sawmill labourers. Several occupations were also identified that have not been previously associated with asthma, suggesting that the risk of occupational asthma may be more widely spread across the workforce than previously assumed.

Risk factors for allergy due to the two-spotted spider mite (Tetranychus urticae) among table grape farm workers

BACKGROUND

Recent studies have reported an increased prevalence of respiratory symptoms among farm workers. The aim of this study was to identify risk factors associated with spider mite allergy among table grape farm workers.

METHODS

A cross-sectional study of 207 workers in table grape farms was conducted. Skin prick tests used extracts of 8 common aeroallergens, grape mould (Botrytis cinerea) and Tetranychus urticae. Specific IgE to T. urticae was quantified using ImmunoCAP (Phadia). Erythrocyte cholinesterase levels were determined using the Test-mate ChE Cholinesterase Test System (model 460).

RESULTS

The average duration of employment of workers was 10 years and 12% were pesticide crop sprayers. Work-related wheeze (26%), ocular-nasal (24%) and urticaria/skin symptoms (14%) were more prevalent in the orchards. The prevalence of sensitization (skin prick test) was highest to T. urticae (22%) followed by house dust mite (16%), with 25% being atopic. The prevalence of allergy to T. urticae (skin reactivity and work-related symptoms) was 9.5%, with respiratory allergy (6%) more common than skin allergy (3%). Work-related ocular-nasal (OR = 4.9) and skin (OR = 3.7) symptoms were more commonly reported by pesticide crop sprayers. Workers with T. urticae-allergic rhino-conjunctivitis and probable asthma were more likely to be atopic, spray pesticides and have low (<30 U/g hemoglobin) erythrocyte cholinesterase levels.

CONCLUSIONS

This study demonstrated that spider mite, T. urticae, is an important outdoor allergen among table grape farm workers. The increased risk of spider mite allergy appears to be related to high pesticide exposure among crop sprayers.

Occupational rhinitis

PURPOSE OF REVIEW

This review updates existing knowledge on occupational rhinitis based on epidemiological and clinical research studies published from 2003 to 2005.

RECENT FINDINGS

The review covers new developments on the pathophysiology, diagnosis, monitoring and management of occupational rhinitis. This article also provides updated information on the prevalence and incidence of both occupational rhinitis and work-related symptoms of rhinitis, as well as on causal agents and personal risk factors associated with this condition.

SUMMARY

Occupational rhinitis is frequently under-diagnosed due to a lack of physician awareness. Diagnosis is suspected when symptoms occur in relation to work. Differentiating between immunological sensitization and irritation may be difficult. Given the high prevalence of rhinitis in the general population from all causes, objective tests confirming the occupational origin are essential. Measures of inflammatory parameters via nasal lavage and objective assessment of nasal congestion both offer practical means of monitoring responses. Growing experience with acoustic rhinometry and peak nasal inspiratory flow suggests that these methods will have an increasingly important role in monitoring and diagnosing in the future. Recent findings indicate that work-related rhinitis is to some extent preventable. Surveillance of sensitized workers may allow early detection of occupational rhinitis.

Brassica oleracea pollen, a new source of occupational allergens

BACKGROUND

Vegetable pollen is a rare source of occupational allergens. Occupational allergy has only been described in the case of paprika pollen and tomato pollen. We describe a new source of occupational pollen allergy.

AIM

To study the incidence and the impact of broccoli and cauliflower pollen allergy in employees involved in classical plant breeding.

METHODS

Fifty-four employees of five companies working with cauliflower (Brassica oleracea botrytis) and broccoli (B. oleracea italica/cymosa) pollen were eligible for complete evaluation. Allergy to cauliflower and broccoli pollen was evaluated by questionnaire and determination of sensitization by radioallergosorbent test (RAST) and skin-prick tests (SPT). SPT and RAST were performed with a panel of commercial and homemade extracts from cauliflower and broccoli pollen.

RESULTS

Work-related symptoms such as rhinitis, conjunctivitis, asthma and urticaria caused by B. oleracea pollen were reported by 44% of the participants (24/54), of whom all but one had positive SPT for cauliflower- and/or broccoli-pollen/flower extracts and 58% (14/24) had positive RAST results. Symptoms had developed within the first 2 years in 33% of the patients. Six patients had to stop or change work.

CONCLUSIONS

Brassica oleracea pollen is a new source of occupational allergen with strong allergenic potential leading to symptoms in almost half of the exposed employees.

Mite allergens

There is an increasing awareness of the health implications of mite sensitivity, as it is closely related to asthma. Mite allergy constitutes a complex worldwide problem, with sanitary and economical implications. Not only are mite species present in house dust, producing potent allergens, but other, less studied species are also responsible for significant allergic reactions in occupational settings. In this review, we focus on the growing number of mite species that are implicated in allergic cutaneous and respiratory diseases in humans. Mite allergy is not restricted only to the human "indoor" environment, because numerous reports clearly demonstrate that many species that can induce sensitization and symptoms are encountered in occupational settings. An important component of allergy research is the evaluation of the allergenic cross-reactivity to verify to what extent different mite species have unique, species-specific, or cross-reactive allergens. The results of these investigations have important clinical consequences for the diagnosis and treatment of allergic diseases. Internationally standardized mite extracts are needed to compare sensitization rates around the world and clearly establish risk factors associated with sensitization and asthma. In spite of recent controversial results, a significant reduction in the exposure to mite allergens continues to be an important challenge and one of the main goals in the treatment of mite-induced respiratory symptoms. In many cases, this reduction must be achieved in the workplace as well as in the home environment.