D2.04 - PREVALENCE OF ALPHA-GAL SENSITIZATION IN PATIENTS WITH ARTHROPOD BITE REACTIONS, CHRONIC SPONTANEOUS URTICARIA AND GASTROINTESTINAL SYMPTOMS IN LA RIOJA (SPAIN). Introduction

Alpha-gal sensitization produces severe allergic reactions related to the consumption of mammalian meat. Currently, tick bites are the main cause involved in the development of a specific IgE response to alpha-gal.  

Recently, the possible relationship between alpha-gal sensitization and other conditions- such as isolated digestive symptoms, reactions to other insect bites or chronic spontaneous urticaria (CSU)- has been investigated. 

The objective of the present study is to estimate the prevalence of alpha-gal sensitization in these three pathologies.

We performed a prospective descriptive study at the Allergy Department of San Pedro University Hospital in Logroño, Spain, including all patients assessed for reactions to arthropod bites, CSU or isolated gastrointestinal symptoms from August 2023 to November 2024.  

Clinical and epidemiological data were collected and specific IgE to alpha-gal was measured in all patients using ImmunoCAP^TM, considering positive values ≥0.10 kU_A/L. 

The control group comprised 100 patients who underwent testing for penicillin allergy.

The sample included 139 patients, of whom 75 had reactions to insect bites, 45 CSU and 19 gastrointestinal symptoms.

Twelve patients (8.4%) were sensitized to alpha-gal compared to 1% in the control group (p=0.017). The mean age was 42.7 years and 83.3% were men. Eleven of these patients (91.7%) reported tick bites and 75% were atopic. None of them had experienced anaphylaxis due to mammalian meat. 

By subgroup, 9/75 (12.2%), 2/45 (4.4%), and 1/19 (5.3%) were sensitized to alpha-gal. The median alpha-gal-specific IgE was 1.99 kU_A/L, 0.33 kU_A/L and 0.63 kU_A/L, respectively.  The odds ratio was 13.5 (95% CI 1.67-109), 4.6 (95% CI 1.19-73.16) and 5.5 (0.33-91.99), respectively.

In our sample, we found a higher prevalence of sensitization to alpha-gal in patients from the study groups- namely those with reactions to insect bites, CSU and isolated gastrointestinal symptoms- compared to those in the control group.  

Therefore, we consider it advisable to ask about a history of tick bites and tolerance to red meats in patients who present with the described conditions, especially in endemic areas. 

Testing for alpha-gal-specific IgE is an affordable and non-invasive tool that can help with the diagnosis in selected patients.