Background: To study the clinical and immunological data of patients affected by a soybean asthma outbreak in Tarragona, Spain.
Patients and methods: Characteristics of previous asthma, emergency rooms records and immediate outcome of 15 patients who attended emergency room departments the epidemic day were recorded. Functional respiratory studies, skin prick tests to aeroallergens, and prick tests, specific IgE and immunoblotting to soybean extracts were performed in all patients.
Results: Thirteen patients were sensitized to soybean proteins. All of them were atopic (most sensitized to house dust mites) and half had started asthma symptoms after their thirties. The epidemic crisis was particularly severe in patients over 50 years, daily chronic asthma, severe obstructive pattern and/or non receiving steroids. Four patients were admitted to intensive care units. Seven patients showed asthma exacerbations (late reactions) 24 h after the beginning of the epidemic crisis. Specific IgE against a 5-6 kD and a 15.5-17 kD soybean proteins was detected in the sera of 8 patients and 10 patients, respectively.
Conclusions: The outbreak affected atopic patients exposed to soybean dust. The severity of the crisis was related with the previous severity of asthma. Besides the well known 5-6 kD allergenic soybean protein, the 15.5-17 kD protein seems also to be implicated in the sensitization of most of these patients.