Occupational rhinitis caused by concurrent sensitization to two different allergens

Background Exposure to wheat flour and guar gum is a well-known cause of occupational respiratory allergies among workers in the food processing industry. To date, there have been no reports of occupational rhinitis (OR) caused concurrently by two different allergens present in the workplace. Aims To report a case of OR likely to be induced concurrently by exposure to wheat flour and guar gum in a mid-40s male employed in the food processing industry. Methods Allergy tests and nasal challenge tests were performed to investigate and confirm the diagnosis of OR. We discuss potential mechanisms involved in the observed dual sensitization. Results The patient showed positive responses to wheat and guar gum extracts on skin prick testing. The total IgE was 1680 kU/l (0-100 kU/l). The diagnosis of OR was confirmed by nasal challenge tests with wheat flour and guar gum on different days. In contrast to the control day, the challenge with flour and guar gum induced an immediate clinical reaction associated with a decrease in nasal volume measured by acoustic rhinometry. The patient was advised to avoid exposure to wheat and guar gum, which resulted in a gradual resolution of nasal symptoms. Conclusions Co-sensitization and cross-reactivity are possible mechanisms involved in cases of concurrent sensitization to related and unrelated allergens in patients complaining of work-related rhinitis symptoms.