In the 2022 American Academy of Allergy, Asthma & Immunology (AAAAI) Annual Meeting, Dr. Anna Nowak-Wegrzyn, Chief of the Pediatrics and Allergy Division at Hassenfeld Children’s Hospital, New York, the United States (US) and Professor at NYU Grossman School of Medicine, delivered a presentation on food protein induced-enterocolitis syndrome (FPIES) as part of the session entitled “Immunoglobulin E (IgE) or Not Immunoglobulin E (IgE): This is the Dilemma-merging Food Allergies”.¹ This presentation aimed to describe the epidemiology of FPIES in the US, its medical management in emergencies, and its long-term dietary management.¹

FPIES is a non-IgE, cell-mediated food allergic disorder characterized by the presence of gastrointestinal symptoms, including delayed emesis, lethargy, pallor, or diarrhea without any typical cutaneous and respiratory allergic symptoms.1 It generally affects 0.51% of the pediatric population and 0.22% of the adult population in the US, predisposing them to other allergic conditions.¹

Acute FPIES is stimulated 1-4 hours after food ingestion and occurs mainly in infants under 12 months, who appear septic with lethargy, limpness, and may present with elevated platelets, as well as polymorphonuclear neutrophil (PMN), shock, and methemoglobinemia in severe cases and watery diarrhea, but symptoms are likely to resolve within 24 hours.¹ In contrast, chronic FPIES is less common. In a study on 203 FPIES patients, including 8 patients with chronic phenotypes, the most common triggers were oat followed by rice and cow’s milk.¹ Chronic FPIES is considered more severe requiring admission to the emergency department for dehydration and metabolic derangements, due to higher prevalence of diarrhea and acute episodes.¹ In cow milk-FPIES, 1 in 4 patients developed positive cow milk-IgE, which was known as atypical FPIES.¹ Food challenge was done on these patients based on their weight, the risk of immediate symptoms and delayed vomiting.1 Additionally, adult-onset FPIES has been more commonly reported in studies with scallop, shrimp, shellfish, dairy, wheat, egg, fish, and crustaceans as food triggers.¹ It differs from the classical presentation in children and is characterized by less diarrhea and more severe abdominal pain associated with nausea and vomiting.

A study in Philadelphia of the US comparing comorbidities between FPIES-positive and FPIES-negative patients showed that atopic dermatitis, IgE-mediated food allergies, asthma, and allergic rhinitis were more common among the FPIES population.¹ Another study from a population-based survey demonstrated that people with eosinophilic esophagitis (EoE) were significantly more likely to report FPIES.¹

Furthermore, new studies have introduced grains as a class of food triggers, which includes oats, rice, wheat, barley and quinoa, followed by cow’s milk, vegetables, fruits, soy and egg.¹

The acute FPIES diagnostic criteria include either 1 major criterion (vomiting within 1-4 hours, absence of skin and respiratory symptoms) or at least 3 minor criteria (>1 episode to the same food, repetitive emesis to another food, lethargy, pallor, emergency room visit, need for intravenous fluids, or diarrhea within 24 hours).¹ However, chronic FPIES is diagnosed by the resolution of symptoms after eliminating the offending food followed by a confirmatory challenge of the offending food and the recurrence of symptoms.¹

Acute FPIES is treated as medical emergency with aggressive fluid hydration in case of hypovolemic shock, single-dose methylprednisolone, ondansetron, vasopressors, or life support in extreme cases.¹ The long-term management of acute FPIES includes eliminating food triggers, periodic reassessment for tolerance once or twice a year, developing feeding skills, introducing and challenging complementary solid food, and having an emergency treatment plan. As such, new guidelines recommend the early introduction of peanuts and eggs to infants, particularly those with atopic dermatitis.¹

In conclusion, FPIES is considered a non-IgE, cell-mediated food allergic disorder that may present as acute, chronic, atypical or adult-onset. Patients with FPIES frequently have IgE-mediated comorbidities, EoE and atopic dermatitis.1 Hence, it is important to encourage the early introduction of low-risk and solid food into diet of infants.