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 bakery and confectionery industry. Sensitization to wheat flour and enzymes such as alpha-amylase are a frequent cause of occupational asthma. Airborne egg allergens have been reported as another cause of respiratory allergy. We examined bakery and confectionery workers with respiratory symptoms due to egg aerosols. Skin tests (SPT), scratch tests (ST), nasal provocation tests (NPT) and serological examinations (IgE) were performed. Lung function was assessed by spirometry, and continuous registration of aerosols and particulates as well as gravimetric sampling was done at the workplace. Four bakery and two confectionery workers intensively exposed to airborne egg proteins suffered from conjunctivitis and rhinitis, four also from asthma. Subsequently, three of these four workers reported symptoms after ingestion of food that contained egg. SPT with commercial egg white and egg yolk extracts were negative in four cases. Only two employees had clearly positive SPT to commercial egg allergens and reacted also to wheat flour extracts. Scratch tests with native egg proteins were positive in four employees. Specific IgE to egg white and egg yolk were positive (CAP > or = 2) in three and in four cases, respectively, whereas they were negative in two cases. Elevated levels of specific IgE to lysozyme were detected in four employees. Two workers were sensitized to lysozyme but not to other egg proteins. 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 (> or = 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 sources of excessive allergen exposure. Bakery and confectionery workers exposed to airborne egg proteins are at risk of developing occupational asthma and subsequent nutritive egg allergy. To our knowledge, these are the first cases of inhalative egg allergy and subsequent nutritive egg allergy reported in the literature, which we refer to as the "egg-egg syndrome" in analogy to the already known "bird-egg" and "egg-bird" syndromes.