Rice (Oryza sativa) belongs, with other cultivated cereals, to different tribes of the Poaceae family. It is one of the most widely produced and consumed cereals in the world but hypersensitivity reactions to this grain are uncommon Most reports describe an immunologically-mediated urticaria due to contact with raw rice or reactions after the inhalation of rice fumes, whereas reports of immediate hypersensitivity reactions after ingestion of rice are scarce.
Methods:
Patient 1 (P1): A 40-year-old-man, a professional cooker, presented two episodes of generalized urticaria minutes after rice ingestion. He tolerated the inhalation of vapours during rice-boiling, but reported icthy skin and erythema after rice handling.
Patient 2 (P2): A 30-year-old-woman, pizzeria-worker for the last 10 years, complaint of sneezing and rhinorrhea after handling rice for the last two years, and presented diarrhea and dysphagia after rice ingestion during the last year. One week before consulting she presented eyelid angioedema, chest tightness and abdominal cramping after doing exercise right after eating rice.
None of the patients reported any additional atopic background. Skin prick tests with common inhalants and cereals extracts, Pru p 3 extract, prick-by-prick test with rice and rice flour and specific IgE determinations to rice were carried out in both patients.
Results:
Skin prick tests to rice was positive in both patients (wheal diameter > 3mm). Skin prick-by-prick with rice and rice flour was also positive in patients 1 and 2. Serum specific IgE determinations against rice showed values of 0.8 kU/L and 1.48 kU/L for P1 and P2, respectively, out from a total IgE of 32.8 UI/mL and 23.7 UI/mL, respectively. SPT to common inhalants, to the rest of the cereals and to Pru p 3, showed a negative result.
Conclusions:
We present two work-related cases of rice allergy with an unusual display and different clinical manifestations (urticaria, rhinitis and anaphylaxis) in two patients without atopic background and who worked handling rice and rice flour. No cross-reactivity with usual panallergens as LTP seemed to be involved.