University of Virginia Holly Springs, NC, United States
Nathan E. Richards, MD1, Thomas Makin, MD2, Anna Smith, MD2, Thomas A. Platts-Mills, MD2, Robert D. Richards, MD3, Jeffrey M. Wilson, MD, PhD2 1University of Virginia, Holly Springs, NC; 2University of Virginia, Charlottesville, VA; 3Gastroenterology Associates of Central Virginia, Lynchburg, VA
Introduction: A syndrome of delayed-onset mammalian meat allergy, mediated by IgE antibodies specific for the oligosaccharide galactose-α-1,3-galactose (α-Gal), was first described in 2009. Bites from Amblyomma americanum (the lone star tick) are a dominant cause of α-Gal IgE sensitization, which explains the high prevalence of the “α-Gal syndrome” (AGS) in the southeastern USA. Urticaria and pruritus are classic manifestations of AGS, however many patients also develop gastrointestinal (GI) symptoms. Increasingly we are aware of patients with AGS who present only with GI symptoms. Here we sought to describe the characteristics of these patients.
Methods: Retrospective chart review was carried out to identify patients with the following characteristics: i) isolated GI symptoms in the absence of urticaria, severe pruritus or anaphylaxis, ii) evidence of α-Gal IgE sensitization, iii) subjective improvement on a mammalian avoidance diet. The review was performed at an academic allergy clinic and a private GI clinic in central Virginia spanning from September 2019 to June 2021.
Results: Thirty five cases were identified in the Allergy practice and 40 in the GI practice. Median age was 63 years and 64% were women. The dominant presentation involved GI pain (83%), often described as cramping. The majority also reported diarrhea (53%), with nausea (33%) and vomiting (9%) being less frequent. The majority of patients did not recognize mammalian meat as a culprit prior to diagnosis. When comparing patients who presented to the GI clinic, patients seen in the Allergy clinic were more likely to report: i) episodes of GI pain/cramping (94% vs 73%), ii) symptoms occurring within 6hrs of eating mammalian meat (51% vs 13%) and iii) history of tick bites (97% vs 53%). Collectively, levels of IgE to α-Gal in these patients were lower than in a previously described cohort of patients with AGS who had urticaria and/or anaphylaxis (GM 1.5 kU/L [95%CI 1.1-2.2] vs GM 16.8 kU/L [13.8-20.5], p< 0.001).
Discussion: Here we present 75 cases of “GI-variant AGS”. These patients presented without classic IgE-mediated symptoms, but were found to be sensitized to α-Gal and reported improvement on a mammal-restricted diet. GI and allergy practitioners in the Southeast and other areas where lone star ticks are endemic should be aware that AGS can present with isolated GI symptoms. Most patients respond to diet of mammalian meat avoidance, but some also benefit from dairy avoidance.
Nathan Richards indicated no relevant financial relationships.
Thomas Makin indicated no relevant financial relationships.
Anna Smith indicated no relevant financial relationships.
Thomas Platts-Mills: Thermo Fisher/ Phadia – Other Financial or Material Support, Has received research support from Thermo Fisher/Phadia. Is a patent holder of alpha-gal IgE assay..
Robert Richards indicated no relevant financial relationships.
Jeffrey Wilson: Thermo Fisher/ Phadia – Other Financial or Material Support, Has received research support and personal fees..
Nathan E. Richards, MD1, Thomas Makin, MD2, Anna Smith, MD2, Thomas A. Platts-Mills, MD2, Robert D. Richards, MD3, Jeffrey M. Wilson, MD, PhD2. P2481 - The α-Gal Mammalian Meat Allergy Manifesting With Isolated Gastrointestinal Symptoms, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.