Commins and Platts-Mills estimated that around 10% of individuals with detectable α-Gal antibodies may display red meat allergy (21). It is, however, unclear exactly what proportion of sensitized individuals experience allergic symptoms after eating mammalian meat. In Sweden, around 10% of 143 healthy blood donors in the greater Stockholm area had IgE antibodies to α-Gal, compared with only 0.7% in the north of the country where tick bites are rare (12). The prevalence of detectable IgE antibodies to α-Gal is highest in areas where Ixodidae ticks are common. In Australia, the suspected tick is Ixodes holocyclus (7, 18), whereas in Europe it is Ixodes ricinus (19) ,and Hematophagous ixodidae in Asia (20). Borrelia burgdorferi, the bacterium that ticks carry causes Lyme disease, does not appear to induce IgE to α-Gal and its bites are not associated with itching (15). ![]() Warming temperatures and the availability of desirable hosts favor the continued range expansion of Lone Star ticks (3), with reported sightings from Maine to Florida, in Wisconsin (16), and as far west as Texas, Oklahoma and Colorado (17). There is a significant correlation between IgE to Lone Star tick bites and antibodies to α-Gal (15). In the US, bites from the Lone Star tick Amblyomma americanum (Figure 1) are the predominant, if not exclusive, cause of α-Gal sensitization (14). On all continents, the ticks responsible for sensitization to α-Gal belong to the Ixodidae family of hard ticks, with each continent harboring its native species. To date, cases of α-Gal-associated meat allergy have been reported in the southeastern (27) northeastern and upper midwestern US (3), Australia (4) Asia (5) and in several European countries, including France (6-8) Spain(9), Germany(10), Switzerland (11), and Sweden (12), Italy (13). ![]() Finally, testing for the presence of IgE to α-Gal could identify a risk factor for medical treatment with cetuximab, eating gelatin-containing substances, or using artificial bovine blood in areas where hard body ticks are common, particularly in individuals with a history of a tick bite or demonstrated allergy to mammalian meat or gelatin (1). Serum tryptase testing can help identify people who may have more severe reactions to tick bites (2). If α-Gal sIgE results represent >2% of total sIgE, a diagnosis of meat allergy is very likely (1). ![]() While negative skin prick test (SPT) results are unreliable, the syndrome can be confirmed by correlating clinical history with the measurement of IgE antibodies to α-Gal. The delayed symptom onset is thought to reflect the appearance of glycolipid α-Gal moieties, which are believed to be involved in the allergic reaction, in the bloodstream.ĭiagnosis of α-Gal-associated meat allergy may not be straightforward, especially in children, as the syndrome can be confused with protein-based meat allergies. A distinctive feature of this allergy is the delayed onset of symptoms, which occurs 2-6 hours after eating meat. The resulting IgE antibodies react with α-Gal epitopes on mammalian meat, resulting in an allergic reaction and in some cases anaphylaxis after eating meat or gelatin. Α-Gal-associated meat allergy is a recently described syndrome in which individuals who have been bitten by ticks of the Ixodidae family become sensitized to the carbohydrate determinant galactose-α-1,3-galactose (α-Gal).
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