The "egg-egg" syndrome: Occupational respiratory allergy to airborne egg proteins with consecutive ingestive egg allergy in the bakery and confectionery industry

Allergies to various inhalative allergens are a serious problem in the bake ry and confectionery industry. Sensitization to wheat flour and enzymes suc h as a-amylase are a frequent cause of occupational asthma. Airborne egg al lergens have been reported as another cause of respiratory allergy. We exam ined bakery and confectionery workers with respiratory symptoms due to egg aerosols. Skin tests (SPT), scratch tests (ST), nasal provocation tests (NP T) and serological examinations (IgE) were performed. Lung function was ass essed by spirometry, and continuous registration of aerosols and particulat es as well as gravimetric sampling was done at the workplace. Four bakery a nd two confectionery workers intensively exposed to airborne egg proteins s uffered from conjunctivitis and rhinitis, four also from asthma. Subsequent ly, three of these four workers reported symptoms after ingestion of food t hat contained egg. SPT with commercial egg white and egg yolk extracts were negative in four cases. Only two employees had clearly positive SPT to com mercial egg allergens and reacted also to wheat flour extracts. Scratch tes ts with native egg proteins were positive in four employees. Specific IgE t o egg,white and egg yolk were positive (CAP greater than or equal to 2) in three and in four cases, respectively, whereas they were negative in two ca ses. Elevated levels of specific IgE to lysozyme were detected in four empl oyees. Two workers were sensitized to lysozyme but not to other egg protein s. The clinical relevance of egg sensitization was confirmed by continuous air sampling and by correlating the onset of the respiratory symptoms which were reflected by a significant decline (greater than or equal to 30%) of the forced one second capacity (FEV1) in two workers. Sieving of egg white powder and an inadequate spray station for liquid eggs were identified as s ources of excessive allergen exposure. Bakery and confectionery workers exp osed to airborne egg proteins are at risk of developing occupational asthma and subsequent nutritive egg allergy. To our knowledge, these are the firs t cases of inhalative egg allergy and subsequent nutritive egg allergy repo rted in the literature, which we refer to as the "egg-egg syndrome" in anal ogy to the already known "bird-egg" and "egg-bird" syndromes.