Living close to the forest is a risk factor for galactose-α-1,3-galactose sensitization

Katja Biering Leth-Møller; Frida Richter Hansen; Marianne van Hage; Simon Francis Thomsen; Allan Linneberg; Lene Jung Kjær

doi:10.1016/j.jacig.2025.100500

Living close to the forest is a risk factor for galactose-α-1,3-galactose sensitization

J Allergy Clin Immunol Glob. 2025 May 27;4(3):100500. doi: 10.1016/j.jacig.2025.100500. eCollection 2025 Aug.

Authors

Katja Biering Leth-Møller¹, Frida Richter Hansen¹, Marianne van Hage^{2

3

4}, Simon Francis Thomsen^{5

6}, Allan Linneberg^{1

7}, Lene Jung Kjær⁸

Affiliations

¹ Center for Clinical Research and Prevention, Copenhagen University Hospital-Bispebjerg and Frederiksberg, Copenhagen, Denmark.
² Division of Immunology and Respiratory Medicine, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.
³ Center for Molecular Medicine, Karolinska University Hospital, Stockholm, Sweden.
⁴ Department of Clinical Immunology and Transfusion Medicine, Karolinska University Hospital, Stockholm, Sweden.
⁵ Department of Dermatology, Copenhagen University Hospital-Bispebjerg and Frederiksberg, Copenhagen, Denmark.
⁶ Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
⁷ Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
⁸ Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.

Abstract

Background: The α-gal syndrome is a food allergy to galactose-α-1,3-galactose present in mammalian meat; it usually develops after tick bites. Despite being considered an emerging health problem, little is known about the geographic risk factors and patterns of α-gal sensitization.

Objective: The aim of this study was to assess geographic clusters of α-gal sensitization and determine whether distance from home address to the forest and tick abundance are risk factors for α-gal sensitization in a Danish adult population.

Methods: We utilized 3 population-based health examination studies that were conducted in 2011-2017 and covered a total of 8742 participants living in a suburban area. All participants were screened for a level of serum-specific IgE to α-gal of 0.1 kU_A/L or higher. Their home addresses were linked with CORINE Land Cover data and a tick prediction model. The associations of (1) distance to the forest and (2) tick abundance with α-gal sensitization were assessed by using multivariable logistic regression.

Results: There were 344 cases of galactose-α-1,3-galactose-specific IgE level being 0.1 kU_A/L; we identified 1 geographic cluster of cases. For every 1 km closer a participant lived to the forest, the odds ratio of α-gal sensitization was 1.09 (95% CI = 1.05-1.13). There were no associations between predicted tick nymph abundance and α-gal sensitization.

Conclusion: In a general, individuals residing in a suburban area had 9% higher odds of being sensitized to α-gal the closer they lived to a forest, thus supporting exposure to ticks as a risk factor for sensitization to α-gal.

Keywords: CORINE Land Cover data; Galactose-α-1,3-galactose; ticks; α-gal syndrome.