S3011 Recurring Gastrointestinal Symptoms as a Novel Presentation of Alpha-Gal Allergy

Abstract

INTRODUCTION: Galactose-alpha-1,3-galactose (alpha-gal) allergy is a delayed allergy after ingestion of mammalian meat such as beef, pork, or lamb. In the literature, symptoms range from urticaria to anaphylaxis with concomitant gastrointestinal manifestations. There are no case reports of adults with abdominal pain as the sole symptom of this allergy. This case delineates a novel presentation of the alpha-gal allergy with a patient with only gastrointestinal symptoms. CASE DESCRIPTION/METHODS: A 46 year old male with a past medical history of hypothyroidism, gastroesophageal reflux disease, hypertriglyceridemia, seasonal allergies and asthma presented with abdominal pain. His first episode occurred two years ago after the ingestion of prime rib, at which time he developed abdominal pain, nausea, and vomiting. Subsequently, he noticed abdominal pain after eating any red meat. Each abdominal pain episode was stabbing in quality and generally lasted two hours. Additional history revealed tick-exposure prior to the first episode of symptoms. Workup confirmed an allergy to beef with an elevated beef alpha-gal IgE of 0.71 kU/L (reference range, <0.35 kU/L). IgE levels were within normal range for pork and lamb. After eliminating all mammalian meat from the diet, the patient’s symptoms resolved. DISCUSSION: The first alpha-gal allergy to mammalian meat was documented in 2006 and it is still not fully understood. It is proposed that remnant alpha-gal from previous mammalian blood meals are transmitted to humans through the saliva of Amblyomma americanum (lone star tick), which is endemic to the southwest region of the United States. After ingestion of mammalian meat containing alpha-gal, the alpha-gal, found in glycolipids, is packaged into chylomicrons. It is released into the thoracic duct and IgE is deployed. It is suspected that this prolonged pathway is why symptoms do not manifest until 3 to 8 hours after ingestion. It is crucial to obtain a good clinical history and recognize that recurrent abdominal pain, nausea or vomiting may be the only presentation especially given that the current mean time to diagnosis is 7.1 years. Diagnosis is made with blood work assessing IgE levels to beef, pork, and lamb. Elevation of IgE titers to only one mammalian meat is required for diagnosis. Given the risk of anaphylaxis, prescription of an epinephrine pen and elimination of mammalian meat is the only treatment.