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. 2023 Apr;130(4):472-478.
doi: 10.1016/j.anai.2022.11.021. Epub 2022 Nov 26.

Tick bite as a risk factor for alpha-gal-specific immunoglobulin E antibodies and development of alpha-gal syndrome

Gilbert J Kersh  1 , Johanna Salzer  2 , Emma S Jones  3 , Alison M Binder  2 , Paige A Armstrong  2 , Shailesh K Choudhary  4 , Grace K Commins  4 , Claire L Amelio  4 , Cecilia Y Kato  2 , Joseph Singleton  2 , Brad J Biggerstaff  3 , Charles B Beard  3 , Lyle R Petersen  3 , Scott P Commins  4
Affiliations

Tick bite as a risk factor for alpha-gal-specific immunoglobulin E antibodies and development of alpha-gal syndrome

Gilbert J Kersh et al. Ann Allergy Asthma Immunol. 2023 Apr.

Abstract

Background: The disaccharide galactose-α-1,3-galactose (alpha-gal) is expressed in mammals other than humans, apes, and old-world monkeys. In humans, elevated immunoglobulin E (IgE) antibodies specific for alpha-gal can result in allergic hypersensitivity known as alpha-gal syndrome (AGS). Case reports and series suggest that tick bites can induce alpha-gal-specific IgE (sIgE) antibodies.

Objective: To evaluate tick exposure as a risk factor for AGS and elevated alpha-gal sIgE level.

Methods: We conducted a case-control study comparing patients with AGS from a North Carolina allergy clinic with controls who were patients at a nearby internal medicine clinic. Cases and controls were administered a questionnaire to obtain information about demographics, home environment, outdoor activities, and recollection of tick bite. Serum samples taken at the time of enrollment were tested for total IgE, alpha-gal sIgE, and antibodies to other tick-borne pathogens.

Results: The patients with AGS were more likely to recall finding a tick on themselves (odds ratio [OR], 11.20; 95% confidence interval [CI], 4.97-25.15), live near wooded forest (OR, 2.27; 95% CI, 0.92-5.55), and spend 17 or more hours per week outdoors in wooded areas (OR, 5.58; 95% CI, 2.56-12.19). The patients with AGS were also more likely to report 4 or more tick bites (OR, 33.05; 95% CI, 9.92-155.12) and reactions at the site of tick bites (OR, 7.93; 95% CI, 3.74-16.80). Furthermore, elevated alpha-gal sIgE level was observed in 33% of the controls and was associated with tick exposure in the controls (OR, 4.25; 95% CI, 2.21-8.18).

Conclusion: The results define tick bite as a risk factor for AGS and elevated alpha-gal sIgE level.

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Conflict of interest statement

Disclosures: Dr Commins is on the speaker’s bureau of Genentech and receives royalties from UptoDate. All other authors have no conflicts of interest to report.

Figures

Figure 1.
Figure 1.
Frequency of AGS cases, by month of onset. The percentage of the case patients with AGS who reported the initial onset of AGS symptoms in each month. AGS, alpha-gal syndrome; Apr, April; Aug, August; Dec, December; Feb, February; Jan, January; Jul, July; Jun, June; Mar, March; Nov, November; Oct, October; Sep, September.
Figure 2.
Figure 2.
(A) Alpha-gal sIgE among the case patients and the controls. The geometric means and 95% confidence intervals are displayed. (B) ROC curve revealing alpha-gal sIgE by case-control status. The threshold is set to 0.59 kU/L to maximize both sensitivity (83%) and specificity (81%). Neg, negative; ROC, receiver operating characteristic; sIgE, specific immunoglobulin E.
See this image and copyright information in PMC

Comment in

References

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Supplementary concepts