D3.287 - Tick Bite–Induced Alpha-Gal Syndrome: A Report of Two Cases and Literature Review Focusing on Clinical Characteristics of Asian Patients

Alpha-gal syndrome (AGS) is an IgE-mediated allergy to mammalian meat, classically triggered by tick bites and characterized by delayed reactions. While extensively described in Western populations, its clinical and diagnostic profile among Asian patients remains poorly characterized. This study aims to delineate the features of AGS in Asian individuals through case presentations and a systematic literature review.

We present two AGS patients diagnosed in 2025 at our center. Diagnosis was confirmed by serum alpha-gal specific IgE (sIgE) testing (Phadia, Thermo Fisher) and skin prick tests (SPT) using commercial lamb extract and freshly prepared pork/kidney extracts (1:10, 1:100 w/v). Antigen binding was further analyzed by indirect ELISA. A systematic literature review was conducted (PubMed, Web of Science, CNKI, Wanfang; up to October 2025) using keywords “alpha-gal syndrome,” “tick bite,” and “red meat allergy” to identify confirmed AGS cases with complete clinical data.

Both patients had clear tick bite histories. Case 1 (80-year-old male) presented with pruritus, syncope, and hypotension 3-4 hours after pork consumption (alpha-gal sIgE: 3.24 kU/L; SPT positive to lamb, pork, and pig kidney). Case 2 (67-year-old female) experienced abdominal pain, diarrhea, urticaria, and dyspnea post-pork ingestion (alpha-gal sIgE: 2.98 kU/L; SPT positive to lamb and pig kidney but negative to pork). ELISA confirmed specific IgE binding to pork/kidney antigens. Symptoms were controlled by red meat avoidance and tick bite prevention.The literature review identified 203 global AGS cases, including 60 from Asia. Among Asian patients, the most common manifestations were urticaria (31.7%), generalized pruritus (68.3%), gastrointestinal symptoms (38.3%), and anaphylaxis (65.0%). While all 60 Asian patients underwent sIgE testing, only 8 (13.3%) received SPT, highlighting a potential underutilization of this diagnostic tool in Asian clinical practice compared to reports from other regions.

AGS is likely underreported in Asia. In tick-endemic areas, AGS should be considered in patients with delayed allergic reactions to red meat. We recommend a combined diagnostic approach using alpha-gal sIgE serology and SPT with fresh meat extracts. Management hinges on strict dietary avoidance and tick bite prophylaxis.