The information in this website is intended only for healthcare professionals. By entering this site, you are confirming that you are a healthcare professional.
The information in this website is intended only for laboratory professionals. By entering this site, you are confirming that you are a laboratory professional.
3 to 6 hours
Symptoms can appear 3 to 6 hours or more after the consumption of mammalian (red) meat.6,7
The greater the number of tick bites, the greater the risk of developing an alpha-Gal sensitization.2
In one study, almost 80 percent of patients with alpha-Gal syndrome weren’t diagnosed for more than seven years.9 This is due to a variety of factors, from the relatively recent discovery of the syndrome, to the common sudden adult onset, to the delay in symptom expression.
Like all food allergies, diagnosing a red meat or alpha-Gal allergy starts with a physical examination and, of critical importance, a food-allergy-focused patient history.10,11
This history can then be used to guide testing decisions and results interpretation. This systematic approach can help determine whether the reported history of food allergy, combined with laboratory data, points to a possible case of alpha-Gal syndrome, or whether other diagnostic pathways should be considered.
Alpha-Gal syndrome is more common in the southeastern and midwestern United States than in other parts of the country.2 This is likely because bites from the Lone Star tick are the predominant cause of the syndrome, and that is where the ticks are most populous.2 Although the exact prevalence of the disease is unknown, it is thought that prevalence is growing—an estimated 10 percent of some U.S. populations may have increased IgE levels of alpha-Gal.12
> 100 cases
41 - 99 cases
5 - 40 cases
1 - 4 cases
Lone Star tick region
Adapted from Platts-Mills T. The Alpha-gal Syndrome: IgE responses to galactose alpha-1,3-galactose induced by bites from lone star ticks.. Presentation presented at AAAI; 2019.
Patients with alpha-Gal syndrome frequently go undiagnosed. However, they’re experiencing symptoms that can range from confusing and unpleasant to deadly. So while they remain undiagnosed, they are likely to make many increased emergency room and provider visits, searching for answers they don’t always get.9 All of this leads to them living in confusion, pain, and fear.
Alpha-Gal is present in all mammals except for humans and old-world monkeys.13 Therefore, mammalian (red) meats such as beef, pork, and lamb are the most common triggers.
But derivatives of red meat can be hiding in a variety of foods that aren’t always clearly labeled, like gelatin-containing foods and dairy.15,18 These derivatives can also be found in many medications and biologic therapies, of which patients need to be aware.14-18
There are also cofactors that relate to anaphylaxis and may increase risk or severity of reaction, including:
Not all triggers are equally likely to cause a reaction—see the chart above for triggers ranked from higher to lower risk.17
Some cross-reactivity occurs during skin-prick testing and the use of immunoassays with meat extracts and other animal-derived antigens. There are three conditions in which cross-reactivity occurs when testing with meat allergens:
When it comes to alpha-Gal syndrome, skin-prick testing (SPT) with commercial meat extracts and raw meats may not reliable. The results are often negative or ambiguous, with weak skin reactions.4,5 In a series of 25 patients with IgE sensitization to alpha-Gal and allergic symptoms after consuming pork kidney, mammalian meat, or gelatin, only two had positive SPT results to commercially available extracts from pork, beef, lamb, or horse meat.19
This is where testing with allergen components comes in. With alpha-Gal allergen component blood testing, providers have access to a quantitative and reliable measure of specific IgE sensitization that can help aid in this especially challenging diagnosis.
Component testing can lead to:
Component testing can also help distinguish cross-reactive patients whose symptoms are caused by pork-cat syndrome from those with alpha-Gal associated meat allergy, helping patients to understand if they need to avoid pork (as in pork-cat syndrome) or red meat altogether (as in alpha-Gal syndrome).21
Adding diagnostic testing to aid in a differential diagnosis has been shown to increase confidence in diagnosis to 90 percent.i,ii Conventionally, a diagnosis of allergic or autoimmune disease relies on the case history and a physical examination. However, adding diagnostic testing to aid in a differential diagnosis has been shown to increase confidence in diagnosis.i,ii Diagnostic testing can also help to improve the patient’s quality of life and productivity, reduce costs associated with absenteeism, and optimize use of medication, in addition to decreasing unscheduled healthcare visits.iii,iv
i. Duran-Tauleria E, Vignati G, Guedan MJ, et al. The utility of specific immunoglobulin E measurements in primary care. Allergy. 2004;59 (Suppl78):35-41.
ii. NiggemannB, Nilsson M, Friedrichs F. Paediatric allergy diagnosis in primary care is improved by in vitro allergen specific IgE testing. Pediatr Allergy Immunol. 2008;19:325-331
iii. Welsh N, et al. The Benefits of Specific Immunoglobulin E Testing in the Primary Care Setting. J Am Pharm Assoc. 2006;46:627.
iv. Szeinbach SL, Williams B, Muntendam P, et al. Identification of allergic disease among users of antihistamines. J Manag Care Pharm. 2004; 10 (3): 234-238
Avoidance of mammalian (red) meat consumption is essential for alpha-Gal-sensitized patients. Management is focused on the avoidance of red meat, as well as further tick bites. Some patients may need to also eliminate dairy and gelatin-containing products from their diets.17
However, the serum level of alpha-Gal-specific IgE and thus the patient’s sensitization may decrease over time after a tick bite. Some patients who avoid subsequent tick bites for one to two years may be able to tolerate red meat again.23
Organ meat is associated with some of the highest allergic reactions in alpha-Gal syndrome.17