Occupational Asthma in Tomato Growers following an Outbreak of the Fungus Verticillium albo-atrum in the Crop

An employee from a large tomato greenhouse presented with symptoms of occupational asthma which on clinical investigation were confirmed to be due to an outbreak of the fungus Verticillium albo-atrum in the tomato crop. A subsequent workplace survey which consisted of the administration of a modified MRC respiratory questionnaire, the recording of peak expiratory flow rates (PEFR), skin prick testing and the measurement of blood precipitins on volunteers from the workforce revealed 2 more cases of occupational asthma which were also investigated clinically. All 3 patients gave a positive response to bronchial challenge with Verticillium albo-atrum extract. The PEFR recordings carried out on the other volunteer members of the workforce showed that those with greater than 20 per cent variability in their PEFR recordings were more likely to complain of cough and/or wheeze (P<0·01). Members of the workforce with positive skin testing to common allergens were more likely to complain of cough and/or wheeze (P<0·05). No association between skin test positivity and greater than 20 per cent variability in PEFR recordings was found. We believe that this is the first report of asthma caused by Verticillium albo-atrum.