Despite point i) above, a significant number of pediatric cases of AGS has been reported and children represent approximately 12% of subjects in one published cohort. However, it is important to realize that some patients with AGS may not present with these characteristics. In many settings, the critical point is for the astute clinician to consider AGS as a possible cause of the patient’s symptoms and Figure 1 is included as a diagnostic algorithm. ĭescription of large local reactions to tick or other arthropod bites, often including report of an ‘index’ bite that behaved differently than prior bites Owing to the ubiquitous inclusion of mammal-derived products within both food and healthcare settings, allergen avoidance for patients with AGS can present unique challenges for management and we routinely include a dietician as part of our care team (or suggest referral). In keeping with this, a minority of patients may benefit from avoiding a wide range of products that are prepared with mammalian-derived constituents. Products such as heart valves, gelatin-based plasma expanders, and pancreatic enzymes, are sources of alpha-gal exposure yet may trigger a reaction in more select patient groups. In addition, multiple medications are derived from mammals and specific mammalian tissues are used as medical devices. For <10% of patients, the avoidance diet also includes removing dairy and derivatives as well as gelatin. Although AGS is no different from other food allergies in this regard, avoidance of mammalian-derived products is more challenging due to a lack of adequate labeling and the inclusion of common components, such ‘natural’ flavorings, in numerous foods. Table 1 is a summary of clinical points accumulated over the last decade caring for patients with AGS.Īllergen avoidance along with rescue medication(s) are the mainstays of management for AGS. Specific to AGS, recent tick bites appear to make patients more sensitive to prior tolerated exposures or even lower threshold for reactivity. In keeping with other food allergies, clinical experience suggests that the presence of co-factors appears to lower the eliciting dose required for reactivity but this requires further study in AGS. The titer of alpha-gal specific IgE does not predict reaction severity rather dose (amount consumed) and presence of co-factors (alcohol, activity) affect the delay before reaction and resulting clinical manifestations. Blood levels of alpha-gal IgE often decrease in patients who avoid recurrent tick bites but the rate of decline varies from patient to patient. An association between AGS and tick bites has been reported throughout the world, despite the differences in tick species and populations. however, no case-control study has confirmed this link. Owing to the geographical range and analysis of tick salivary factors, the lone star tick (Amblyomma americanum) appears to be the primary cause of AGS in the U.S. įollowing identification of AGS, patients with the same allergy in Australia, Europe, Scandinavia, Japan, and South Africa have been reported. Thus, many patients fail to consider food as a possible trigger and many healthcare providers do not routinely recognize the characteristic delay – both issues can prolong time to reach a diagnosis. Unlike more traditional food allergies where consumption of an allergen produces symptoms within minutes, AGS reactions typically occur 3-8 hours after eating. The combination of both an appropriate clinical history and supporting blood test is necessary to establish an accurate AGS diagnosis. In >90% of cases the diagnosis of AGS can be made based on a history of delayed allergic reactions after eating non-primate mammalian meat * (e.g., “red meat” such as beef, pork, or lamb) and a positive blood test (>0.1 IU/mL) for IgE to alpha-gal. This clinical observation was supported by prior identification of immunoglobulin E (IgE) specific for the oligosaccharide galactose-α-1,3-galactose (alpha-gal) that was associated with hypersensitivity reactions (HSRs) to cetuximab. In 2009 Alpha-gal Syndrome (AGS) was described in 24 patients who reported delayed allergic reactions to mammalian meat.
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