Occupational asthma due to poultry mites.

The possible role of the northern fowl mite (NFM) in occupation-related respiratory disease of poultry workers was examined. The study population included 16 poultry workers with workplace-associated asthma and rhinitis, 27 atopic individuals with similar symptoms but no occupational exposure to poultry, and 12 asymptomatic nonatopic poultry-exposed controls. Ten of the 16 atopic poultry workers had immediate wheal-and-flare reactions to NFM, as compared with two of 27 non-poultry-exposed controls (p less than 0.001). In cutaneous testing with five poultry-related antigens, the NFM was the most reactive. On skin tests, four atopic poultry workers were positive for NFM and negative for Dermatophagoides farinae; four workers were negative for NFM and positive for D. farinae. Radioallergosorbent test (RAST) showed specific IgE levels for NFM, with positive RAST scores in 60% of poultry workers having positive skin tests. A provocative bronchial test with NFM extract in a poultry worker having positive NFM skin test and RAST score resulted in an immediate 25% reduction in the FEV1 and a 62% fall in forced expiratory flow volume at 25% of vital capacity. Collectively, the established presence of NFM in the poultry workplace, associated clinical histories, positive cutaneous tests, positive specific-IgE assays, and positive bronchial challenge combine to establish a role for NFM in occupational allergic respiratory disease of poultry farmers.