Could ticks and worms both cause red meat allergy?

Published online: July 28, 2021

Alpha-gal allergy or alpha-gal syndrome (AGS) allergy is a type of meat allergy with a delayed onset of symptoms (3-8 hours) after ingesting mammalian meat. Tick bites are known to induce sensitization and result in allergy, but the exact mechanism of how a tick bite causes human sensitization against alpha-gal and leads to the development of AGS, is poorly understood.

In The Journal of Allergy and Clinical Immunology (JACI), Levin and colleagues collected and examined common ecto- and endo-parasites for the presence of alpha-gal containing proteins, and determined the relative concentrations of alpha gal, and where in the parasites’ bodies the alpha-gal is situated. They then used a lab-based allergy simulation experiment to investigate whether extracts and proteins found in these parasites can trigger an alpha-gal type reaction. The authors demonstrate the presence of alpha-gal containing proteins in two new tick species, and unexpectedly showed an extremely high concentration of an alpha-gal containing protein in the common intestinal parasite Ascaris lumbricoides. In ticks, alpha gal proteins are localized to the salivary glands, whereas in A. lumbricoides, the proteins are found predominantly in the gut and are not excreted or secreted by the worms. Moreover, the authors found that the worm extracts and pure worm proteins, are able to induce an allergic reaction in allergy cells that have been primed with serum from patients with alpha-gal allergy, implying that A. lumbricoides infection may cause sensitization to alpha-gal and even lead to meat allergy.  

One of the persistent mysteries in research on meat allergy is the mechanisms by which the initial sensitization to alpha-gal occurs. This research broadens the range of possible sensitizing triggers. With the higher amount of alpha-gal found in A lumbricoides than common ticks, why then, is alpha-gal allergy associated more strongly with tick bites? Perhaps additional factors, like the route of exposure, and the presence of additional immune-boosting “adjuvants” in tick saliva is responsible for the difference?  

The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.

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