Laboratory animals and respiratory allergies: the prevalence of allergies among laboratory animal workers and the need for prophylaxis

Exposição prolongada a animais de laboratório está associada ao aumento de casos de asma

Resumo Objetivo: descrever o resultado do acompanhamento de trabalhadores sensibilizados a animais de laboratório que prolongaram sua exposição. Métodos: após um período de aproximadamente 7 anos, entramos em contato com todos os indivíduos com sensibilização alérgica ocupacional detectada em estudo anterior. Um questionário foi aplicado para situação ocupacional atual, relação entre alergia e a decisão de deixar o trabalho ou exposição e para asma, sibilância, rinite, sintomas cutâneos e dispneia noturna. Resultados: dos 74 indivíduos com sensibilização ocupacional, 45 responderam ao questionário na segunda avaliação e 37 ainda estavam expostos. Ao comparar os dados da primeira avaliação com os da avaliação atual, observou-se um aumento na frequência de asma. Na primeira avaliação, entre todos os sensibilizados (n = 74), 27,0% responderam sim a ambas as questões “Você tem ou já teve asma?” e “A asma foi diagnosticada por um médico?”. Na segunda avaliação, 7 anos depois, dos 37 sujeitos que ainda estavam expostos, 51,3% responderam sim a essas questões (OR: 2,80; IC95%: 1,23-6,38; p = 0,013). Não houve mudança na frequência de respostas positivas às outras perguntas. Conclusão: os dados demonstram aumento da frequência de asma entre trabalhadores com sensibilização ocupacional que prolongam a exposição a animais de laboratório.

Allergy to Mus m 1: Allergy to Mus m 1: A review of structural, and immunological features

The prevalence of allergies to pets has been increasing over the past decades. Some of the most important animal-derived allergens are members of the lipocalin protein family, which are found in dander, saliva, and urine. These allergens disperse effectively and are widely present in indoor environments. Exposure to high levels of mouse urinary protein (Mus m 1, hereinafter called 'mouse allergen') has been previously linked to sensitization to mouse, and indicators of asthma severity or control in some studies. To date, this is the only known mouse allergen registered in the IUIS database. This allergen is responsible for 27% of the total T cell response, confirming the dominant role it plays in mouse allergy. Mice have a worldwide distribution affecting both rural and urban areas; hence humans are frequently exposed to mouse-derived proteins. Additionally, exposure to mouse allergens has increased since they are more frequently being made pets, and in addition, exposure of laboratory animal care personnel to mice has been associated with a high risk of developing occupational allergies. Mus m 1 has been recognized as the main mouse allergen, and several studies suggest its clinical relevance. What makes Mus m 1 such an important allergen? In this review, we explored its structural, immunological, and clinical features.

Cat ownership is associated with increased asthma prevalence and dog ownership with decreased spirometry values

The association between pet ownership and the development of allergic and respiratory diseases has been the aim of several studies, however, the effects of exposure in adults remain uncertain. The aims of the present study were to investigate the prevalence of asthma and lung function status among dog and cat owners. This cross-sectional study was performed at two universities with students and workers who were allocated into 3 groups according to pet ownership in the previous year: cat owners, dog owners, and no pets (control group). Subjects underwent spirometry, bronchial challenge test with mannitol, skin prick tests, and questionnaires about animal exposures and respiratory symptoms. Control group comprised 125 subjects; cat owner group, 51 subjects; and dog owner group, 140 subjects. Cat owners had increased asthma prevalence (defined by symptoms and positive bronchial challenge test), but no changes in lung function compared to the control group. The dog owner group had lower spirometry values (forced expiratory volume in one second and lower forced vital capacity), but similar asthma prevalence, compared to the control group. In the cat owner group, excess of asthma may have an immunological basis, since we found an association with atopy. Although we did not have endotoxin data from volunteers' households, we postulated that low values of lung function were associated to exposure to endotoxins present in environments exposed to dogs.

Laboratory animal allergy reduction from 2001 to 2016: An intervention study

Exposure to laboratory animals (LA) can cause allergic sensitization and symptoms as rhinitis, conjunctivitis, asthma, anaphylaxis and dermatitis. In 2000, a program was instituted at Trieste Universities to decrease LA allergy among scientists and technicians working with animals. The aim of our study was to investigate LA allergy in workers exposed to LA from 2001 to 2016, and to verify the effects of a preventive program. Four hundred sixty seven people underwent pre-employment screening for a job with laboratory animals at Universities of Trieste consisting in a medical examination, a full respiratory and allergy anamnesis, using a standardized questionnaire, skin prick test with common and occupational allergens, and spirometry. Every year, each worker repeated the medical examination and underwent again tests and questionnaire. Each worker can ask for a medical examination and skin prick test, in case of unset of symptoms. Logistic multivariate analysis and generalized equation estimation were use, to verify factors associated to LA allergy. Sensitization to LA decreased in years, going from 25.6% in 2001-2004 to 8.2% in 2013-2016 (p < 0.001). Multivariate logistic regression analysis confirmed the role of atopy by prick test (OR = 6; IC95% 2.2-16.6), of common allergic symptoms (OR = 2.9; IC95% 1.4-6.39) and of calendar periods. No association was found between LA allergy, years, and hours of exposure. Our study demonstrated a significant reduction of LA allergy after the application of a preventive program.

The efficacy and safety of mannitol challenge in a workplace setting for assessing asthma prevalence

OBJECTIVE

There is no standard definition of asthma for epidemiological purposes; most surveys use symptoms and bronchial hyperresponsiveness. Few studies tested mannitol challenge test (MCT) in occupational settings. We sought to determine efficacy and safety of MCT in detecting subjects with asthma symptoms in the workplace.

METHODS

In this cross-sectional study we recruited 908 workers in 2 universities; they underwent a respiratory questionnaire, spirometry, skin prick tests, and MCT.

RESULTS

Eight hundred and eleven subjects completed the study; 11.1% had a positive MCT; 8.14% had asthma. MCT had low sensitivity (35.4-61.9%) but high specificity (90.2-94.9%) to detect symptomatic individuals. The most prevalent symptom was wheezing in the last 12 months. Twenty-four of those with a positive MCT (26.7%) had no positive replies to the questions on asthma symptoms. Among subjects with a positive MCT, 71.9% achieved 95% of baseline FEV₁ after 15 minutes of salbutamol recovery treatment. Nine subjects (1.1%) had adverse events that prevented the test from being completed.

CONCLUSIONS

MCT has high specificity but low sensitivity to detect symptomatic subjects in the workplace. It may detect subjects with hyperresponsiveness but no symptoms, who could be at risk of developing airway diseases. The test is safe and well tolerated.

Allergic sensitization to laboratory animals is more associated with asthma, rhinitis, and skin symptoms than sensitization to common allergens

BACKGROUND

Workers exposed to laboratory animals have a high risk of developing laboratory animal allergy (LAA). Atopy seems to be the main risk factor for LAA. We hypothesized that occupational sensitization is a better predictor for the development of asthma, rhinitis, and bronchial hyperresponsiveness (BHR) than common sensitization.

OBJECTIVE

To investigate the association between occupational sensitization to laboratory animals and clinical outcomes.

METHODS

This was a cross-sectional study performed at two universities on students and employees dealing with small rodents. The subjects were allocated in groups: non-sensitized, common sensitization, or occupational sensitization, according to the results of the skin prick test (SPT). All subjects answered a questionnaire about animal exposures, symptoms, allergic diseases, and underwent spirometry and bronchial challenge test with mannitol. Multivariate analysis was performed using Poisson regression to estimate the prevalence ratio (PR).

RESULTS

Data from 453 volunteers were analysed. Non-sensitized group comprised 237 subjects; common sensitization group, 142 subjects; and occupational sensitization group, 74 subjects. Occupational sensitization was associated with greater risk for all outcomes studied. When the common sensitization group was reference, skin symptoms had PR of 1.36, 95% confidence interval (CI): 1.01-1.85; wheezing had PR of 1.75, CI 95%: 1.21-2.53; rhinitis had PR of 1.25, 95%: 1.11-1.40; nocturnal dyspnoea had PR of 2.40, 95% CI: 1.31-4.40; bronchial hyperresponsiveness (BHR) had PR of 2.47, 95% CI: 1.50-4.09; and confirmed asthma had PR of 2.65, 95% CI: 1.45-4.85. In addition, the overlap of asthma, rhinitis, and skin symptoms in a same subject was significantly more prevalent in the occupational sensitization group, 16.2% versus 4.9% in the common sensitization group.

CONCLUSION AND CLINICAL RELEVANCE

Occupational sensitization is associated with allergic symptoms and respiratory diseases. SPT with occupational allergens along with other parameters may contribute to detection of risk for allergic and respiratory diseases associated with exposure to laboratory animals.

Exposure to high endotoxin concentration increases wheezing prevalence among laboratory animal workers: a cross-sectional study

Background

Endotoxin from Gram-negative bacteria are found in different concentrations in dust and on the ground of laboratories dealing with small animals and animal houses.

Methods

Cross-sectional study performed in workplaces of two universities. Dust samples were collected from laboratories and animal facilities housing rats, mice, guinea pigs, rabbits or hamsters and analyzed by the “Limulus amebocyte lysate” (LAL) method. We also sampled workplaces without animals. The concentrations of endotoxin detected in the workplaces were tested for association with wheezing in the last 12 months, asthma defined by self-reported diagnosis and asthma confirmed by bronchial hyperresponsiveness (BHR) to mannitol.

Results

Dust samples were obtained at 145 workplaces, 92 with exposure to animals and 53 with no exposure. Exposed group comprised 412 subjects and non-exposed group comprised 339 subjects. Animal-exposed workplaces had higher concentrations of endotoxin, median of 34.2 endotoxin units (EU) per mg of dust (interquartile range, 12.6–65.4), as compared to the non-exposed group, median of 10.2 EU/mg of dust (interquartile range, 2.6–22.2) (p < 0.001). The high concentration of endotoxin (above whole sample median, 20.4 EU/mg) was associated with increased wheezing prevalence (p < 0.001), i.e., 61 % of workers exposed to high endotoxin concentration reported wheezing in the last 12 months compared to 29 % of workers exposed to low endotoxin concentration. The concentration of endotoxin was not associated with asthma report or with BHR confirmed asthma.

Conclusion

Exposure to endotoxin is associated with a higher prevalence of wheezing, but not with asthma as defined by the mannitol bronchial challenge test or by self-reported asthma. Preventive measures are necessary for these workers.

Occupational Rhinitis

Occupational rhinitis (OR) involves nasal congestion, rhinorrhea, nasal itching, and/or sneezing resulting from workplace exposures. OR can have a significant negative effect on quality of life and productivity. OR can be divided into allergic or nonallergic subgroups based on the underlying pathogenesis. Certain occupational exposures place employees at greater risk for developing disease. Primary treatment is avoidance of implicated exposures. Antihistamines, saline rinses, and nasal steroids may be useful. OR can coexist with occupational asthma, and rhinitis symptoms have been reported to precede those of the lower respiratory tract. OR is has both medical and socioeconomic implications.

Study of risk factors for atopic sensitization, asthma, and bronchial hyperresponsiveness in animal laboratory workers

OBJECTIVES

The aim of this estudy was to investigate the influence of allergen exposure levels and other risk factors for allergic sensitization, asthma, and bronchial hyperresponsiveness (BHR) in workers exposed to laboratory animals.

METHODS

This was a cross-sectional study performed at two universities, 123 workplaces with 737 subjects. Dust samples were collected from laboratories and animal facilities housing rats, mice, guinea pigs, rabbits, or hamsters and analyzed by enzyme-linked immunosorbent assay (ELISA) to measure allergen concentrations. We also sampled workplaces without animals. Asthma was defined by both symptoms and BHR to mannitol. The concentrations of allergens were tested for association with a skin prick test, respiratory symptoms, spirometry data, and BHR. This multivariate analysis was performed by using Poisson regression to estimate the relative risk (RR) for the exposed group.

RESULTS

Our sample comprised students and workers, with 336 subjects in the nonexposed group and 401 subjects in the exposed group. Sixty-nine subjects (17%) had positive results in the skin prick test for animal allergens in the exposed group; in the nonexposed group, 10 subjects had positive results (3%) (p<0.001). Exposure to laboratory animals over 2.8 years was associated with atopic sensitization (RR=1.85; 95% confidence interval: 1.09-3.15; p=0.02). Allergen concentration was not associated with sensitization, asthma, or BHR.

CONCLUSION

Exposure to laboratory animals was associated with atopic sensitization. However, we did not find a cutoff allergen concentration that increased the risk for sensitization. Duration of exposure seems to be more relevant to sensitization than concentration of allergens in dust.

Occupational rhinitis: an update

Occupational rhinitis is characterized by nasal congestion, rhinorrhea, nasal itching, and/or sneezing that occur secondary to exposures in the workplace. This disease can be classified into allergic or nonallergic subgroups based upon the underlying disease pathogenesis as well as the type of causative agent. While the true prevalence of occupational rhinitis is unknown, there are certain professions and occupational exposures that place workers at a higher risk for developing the disease. Additionally, occupational rhinitis can be associated with occupational asthma and upper airway symptoms may precede those of the lower respiratory tract. Taken together, occupational rhinitis is an important disease for study given its medical as well as socioeconomic implications. This review will focus on the classification of occupational rhinitis as well the prevalence, diagnosis, and treatment strategies.