Unusual Causes of Food-Induced Anaphylaxis - A Review.

abstractAnaphylaxis is a potentially fatal, acute, multisystemic hypersensitivity reaction. Food-induced anaphylaxis (FIA) is typically an IgE-mediated reaction. Although any food has the potential to cause FIA, there are some less well-known causes that have unusual cofactors/triggers, which pose diagnostic challenges and are often classified as idiopathic anaphylaxis. We describe three unusual causes of FIA in this review and discuss testing strategies in resource-limited settings. These include wheat-dependent exercise-induced anaphylaxis (WDEIA), alpha-gal syndrome, and pork-cat syndrome. WDEIA develops when wheat consumption occurs, along with exercise and additional cofactors like seafood, alcohol, and/or nonsteroidal anti-inflammatory drugs. The major allergen is omega-5 gliadin, a protein component of the gluten fraction of wheat. Symptoms vary from intermittent urticaria and/or angioedema to severe anaphylaxis. Alpha-gal syndrome is a condition in which delayed allergy symptoms (2-4 hours later) develop after consumption of red meat, where sensitization to the carbohydrate develops following a tick bite. Pork-cat syndrome is a rare condition where patients sensitized to cat epithelium develop allergic symptoms on eating pork. An accurate history, followed by skin prick testing and blood tests for specific IgE to culprit allergens, forms the cornerstone of diagnosis. Awareness of these entities, particularly with changing dietary habits and the ease of international travel, is essential for appropriate diagnosis and management.