Food protein-induced enterocolitis syndrome (FPIES) following COVID-19 infection: a case report.

Introduction: Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated form of food allergy characterized by gastrointestinal manifestations following ingestion of the offending food. Most cases are identified during the first year of life, most frequently triggered by cow's milk or soy; however, alternative clinical phenotypes beyond this classic presentation have also been reported. In this case, we report a patient who developed acute FPIES to cow's milk ingestion following a COVID-19 infection, despite previous tolerance to cow's milk. This case raises the hypothesis that viral infections such as COVID-19 may act as cofactors or unmasking events in the development of FPIES. Case presentation: We report a 10-month-old boy who experienced recurrent episodes of profuse vomiting, followed by persistent diarrhea, beginning at 25 days of age-just a few days after a COVID-19 viral illness-with subsequent resolution upon transition to an amino acid-based formula. An oral food challenge (OFC) with cow's milk triggered repetitive emesis within 2 h of ingestion, accompanied by pallor, lethargy, severe diarrhea, and hypotension, which required multiple fluid boluses. The patient was admitted to the intensive care unit for monitoring of FPIES complicated by fluid-responsive hypovolemic shock. Clinical improvement was observed within 24 h of re-initiating amino acid-based formula, and the patient was discharged after 48-72 h with complete resolution of symptoms. Conclusions: A review of the literature revealed no prior reports of FPIES precipitated by viral infections. This case highlights a noteworthy temporal association between COVID-19 infection and the subsequent onset of FPIES in a patient who had previously tolerated cow's milk formula. Further studies are warranted to explore the possibility of viral infection induced FPIES.