Occupational allergy to phytase: case series of eight production workers exposed to animal feed additives

Summary Background In agricultural meat production, adding enzymes such as phytase to animal feed is widespread, but there is little awareness of the allergenic potential and health risks of these fungal enzymes. Patients and Methods We report on eight patients working in a plant producing phytase granulates. All patients complained about work‐related rhinitis occurring within six months of the onset of exposure to phytase dust. Asthmatic symptoms and contact urticaria also occurred. To detect sensitizations to phytase, skin prick‐, patch‐, and basophil activation test were carried out with the factory product. Levels of IgE and IgG against phytase were also measured. Results There was a positive reaction to phytase with skin prick testing in seven of the eight patients. IgE specific to phytase was detectable in four of the eight patients, and IgG specific to phytase was detectable in six of the eight patients. The basophil activation test was positive in four out of seven patients tested, but the patch test was negative in all patients tested. Transfer to a different workplace with no exposure to phytase completely eliminated the symptoms. Conclusions Mold enzymes such as phytase are highly potent occupational allergens. Occupational safety measures must be strictly implemented in order to protect the health of workers.