Allergic reactions to animals are among the most common conditions that adversely affect the health of workers involved in the care and use of animals in research (NRC 1997). Of the 90,000 laboratory animal workers in the United States (Bland et al. 1987), up to 46% develop allergy to laboratory animals. Of those who develop symptoms, more than 10% eventually develop occupationrelated asthma with symptoms that persist even after exposure ceases. A rare but life-threatening consequence of laboratory animal allergy (LAA1) is an anaphylactic reaction to animal bites, scratches, and needle sticks carrying the animal proteins. The manifestations of animal allergy, which range from rhinitis and itchy eyes to respiratory distress, have caused more than one third of laboratory animal workers at the National Institutes of Health to lose time from work (Bland et al. 1986).
Laboratory animal allergy (LAA) is a form of occupational allergic disease. The development of LAA is due to the presence of immunoglobulin E antibodies directed against animal proteins. The process of sensitization (development of immunoglobulin E antibodies) is a complex process that involves interaction of antigen-presenting cells and lymphocytes of the Th-2 cell type. These cells generate a host of cytokines and other factors that lead to immediate hypersensitivity reactions and the generation of allergic inflammation. Typical symptoms of LAA include nasal symptoms (e.g., sneezing, watery discharge, and congestion) and skin rashes. Asthma, which produces symptoms of cough, wheezing, and shortness of breath, may affect 20 to 38% of workers who are sensitized to laboratory animal allergens. Rarely, a generalized, life-threatening allergic reaction (anaphylaxis) may occur. The estimated prevalence of LAA is variable, depending on the method used for diagnosis, but nonetheless may affect exposed workers. The presence of pre-existing allergies to nonworkplace allergens (e.g., dust mite, pollens, molds), exposure to laboratory animal allergens, and possibly tobacco smoking are risk factors for the development of LAA. Progress in the understanding of the mechanism and epidemiology of LAA will lead to improved methods for its prevention.
Allergic sensitivity to laboratory animals can pose a significant occupational hazard to anyone with regular animal contact. Reactions to mice and rats are most common, although all furred animals produce allergens that can lead to sensitization and disease. Most of the relevant allergens of laboratory animals have been defined and characterized, which has revealed that these allergens are typically small, acidic glycoproteins and that many of them are members of a superfamily of extracellular proteins called lipocalins. In addition to understanding their molecular characteristics, the identification of these allergens has also made it possible to measure their distribution in laboratory environments and to relate exposure levels to sensitization and symptoms. These studies have shown that the major laboratory animal allergens are carried on small particles that are both capable of remaining airborne for extended periods and penetrating into the lower airways of exposed workers. These advances in the understanding of these important occupational allergens will allow for the development of better methods of diagnosis and avoidance for affected workers and others who may be at risk for future difficulties.
Laboratory animal allergy (LAA) is a significant occupational disease that may affect up to one third of personnel exposed to laboratory animals. Research has characterized the relative risks of exposure in terms of intensity, frequency, and duration associated with given tasks and work areas in the animal facility. Studies have shown that reduced exposure to animal allergens can reduce the incidence of LAA and relieve symptoms among affected workers. A combination of measures to eliminate or control allergen exposure, including engineering and administrative controls and personal protective equipment, have been integral components of effective LAA management programs. This article provides a comprehensive review of exposure control options, considerations, and “best practices” relative to laboratory animal allergen in the context of traditional industrial hygiene methods.
In the United Kingdom, laboratory animal allergy (LAA) has been recognized as an important occupational disease for nearly 25 yr. However, introduction of health and safety legislation (e.g., the Control of Substances Hazardous to Health Regulations of 1988) and an increasing knowledge of the factors that contribute to the etiology of this disease have had surprisingly little impact on the prevalence and incidence of LAA over the last 10 to 20 yr. Studies of the relation between exposure to animal allergens and the development of LAA reveal that the risk of disease increases with increasing intensity of exposure. Current evidence suggests that animal allergens are very potent, and substantial decreases in allergen exposure are therefore necessary before a reduction in symptoms will be observed. In the United Kingdom, it is unlikely that an Occupational Exposure Limit will be set for animal allergens in the near future, partly because an adequately standardized assay for quantifying exposure is not yet available. Prevention of LAA in the future will probably be driven by the needs of the industry and will most likely rely on the adoption of guidelines describing “best practise,” which incorporate sophisticated engineering methods of controlling exposure to animal allergens.
Alergic disease is a serious occupational health concern for individuals who have contact with laboratory animals. Principal respiratory symptoms include allergic rhinitis, conjunctivitis, and asthma. Urticaria ("hives") is the most common skin manifestation. The overall prevalence of allergic disease among laboratory animal handlers is about 23%, and respiratory allergy is much more common than skin allergy. Prevention of animal allergy depends on control of allergenic material in the work environment. Personal protective equipment such as air filtering respirators should be used in addition to the other exposure control technologies where conditions require. Preplacement evaluation and periodic medical surveillance of workers are important aspects of the overall occupational health program. The emphasis of these medical evaluations should be on counseling and early disease detection. The article provides recommendations for the content of the medical evaluations.
Laboratory animal allergy (LAA) is a form of occupational sensitivity affecting up to one third or more of exposed workers. Symptoms involve the eyes, nose, skin, and lower respiratory tract. Asthma may develop in 20 to 30% of sensitized individuals. An occupational medical history is the primary tool if a diagnosis of LAA is suspected. The diagnosis is confirmed by demonstrating the presence of immunoglobulin E antibodies to laboratory animal allergens by skin testing or in vitro assays. If laboratory animal allergen-induced asthma is suspected, measurements of lung function are necessary for confirmation and assessing the degree of impairment. One approach to the problem is presented in this article. For individuals with LAA, avoidance of exposure is the primary treatment. For individuals who continue to work in the environment, pharmacological treatment of their symptoms may be necessary. Methods to prevent the development of LAA are also discussed.
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