Title: Mammalian meat allergy (alpha-gal syndrome) following tick bites - Dan Gingold, MD, MPH<br/>Author: Michael Bond<br/><a href='http://umem.org/profiles/faculty/78/'>[Click to email author]</a><hr/><div style="clear:both;">
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<span data-contrast="none" xml:lang="EN-US">Title: </span><span data-contrast="none" xml:lang="EN-US">Mammalian</span><span data-contrast="none" xml:lang="EN-US"> meat allergy (alpha-gal </span><span data-contrast="none" xml:lang="EN-US">syndrome</span><span data-contrast="none" xml:lang="EN-US">) following tick bites</span></p>
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<span data-contrast="none" xml:lang="EN-US">Author: Dan Gingold, MD, MPH</span></p>
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<span data-contrast="none" xml:lang="EN-US">Development of </span><span data-contrast="none" xml:lang="EN-US">IgE</span><span data-contrast="none" xml:lang="EN-US"> antibodies to the oligosaccharide galactose-alpha-1-3-galactose (alpha-gal) appears to be responsible for</span><span data-contrast="none" xml:lang="EN-US"> an</span><span data-contrast="none" xml:lang="EN-US"> acquired allergy to </span><span data-contrast="none" xml:lang="EN-US">non-primate </span><span data-contrast="none" xml:lang="EN-US">mammalian</span><span data-contrast="none" xml:lang="EN-US"> meat</span><span data-contrast="none" xml:lang="EN-US"> (</span><span data-contrast="none" xml:lang="EN-US">i.e., </span><span data-contrast="none" xml:lang="EN-US">beef and pork)</span><span data-contrast="none" xml:lang="EN-US"> and derived products</span><span data-contrast="none" xml:lang="EN-US">. </span><span data-contrast="none" xml:lang="EN-US">Antigen in the salivary apparatus of certain ticks (gross!!) </span><span data-contrast="none" xml:lang="EN-US">can sensitize</span><span data-contrast="none" xml:lang="EN-US"> an </span><span data-contrast="none" xml:lang="EN-US">IgE</span><span data-contrast="none" xml:lang="EN-US">-mediated response </span><span data-contrast="none" xml:lang="EN-US">to alpha-gal which is present in mammalian meat. </span></p>
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<span data-contrast="none" xml:lang="EN-US">Symptoms are similar to other </span><span data-contrast="none" xml:lang="EN-US">IgE</span><span data-contrast="none" xml:lang="EN-US">-mediated hypersensitivity reactions,</span><span data-contrast="none" xml:lang="EN-US"> and can cause</span><span data-contrast="none" xml:lang="EN-US"> a</span> <span data-contrast="none" xml:lang="EN-US">delayed-onset reaction</span><span data-contrast="none" xml:lang="EN-US"> with hives, GI upset,</span><span data-contrast="none" xml:lang="EN-US"> or anaphylaxis</span><span data-contrast="none" xml:lang="EN-US"> after ingestion of red meat</span><span data-contrast="none" xml:lang="EN-US">. Treatment </span><span data-contrast="none" xml:lang="EN-US">with standard </span><span data-contrast="none" xml:lang="EN-US">anti-histamines and epinephrine</span><span data-contrast="none" xml:lang="EN-US"> is effective</span><span data-contrast="none" xml:lang="EN-US">. </span><span data-contrast="none" xml:lang="EN-US">Individuals with no prior history of meat sensitivity can develop the syndrome at </span><span data-contrast="none" xml:lang="EN-US">any age, </span><span data-contrast="none" xml:lang="EN-US">often after</span><span data-contrast="none" xml:lang="EN-US"> exposure to </span><span data-contrast="none" xml:lang="EN-US">the outdoors in tick-endemic areas</span><span data-contrast="none" xml:lang="EN-US">. </span><span data-contrast="none" xml:lang="EN-US">Skin and blood allergy testing can confirm the diagnosis.</span> <span data-contrast="none" xml:lang="EN-US">Symptoms can persist for years, but can recede over time if not exposed to further tick bites.</span></p>
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<span data-contrast="none" xml:lang="EN-US">In the US, the primary tick responsible is </span><span data-contrast="none" xml:lang="EN-US">Lone Star Tick (</span><span data-contrast="none" xml:lang="EN-US">Amblyomma</span> <span data-contrast="none" xml:lang="EN-US">americanum</span><span data-contrast="none" xml:lang="EN-US">)</span><span data-contrast="none" xml:lang="EN-US">, found primarily in the Eastern, Southeastern, and Midwestern US</span><span data-contrast="none" xml:lang="EN-US">. Other tick species in Europe, Australia, and Asia have been found to induce the syndrome as well.</span> <span data-contrast="none" xml:lang="EN-US">Interestingly, there is a cross-reactivity with the monoclonal antibody Cetuximab (used to treat colorectal and head and neck cancers), an allergic reaction to which can also induce similar alpha-gal meat sensitivity.</span></p>
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<span data-contrast="none" xml:lang="EN-US">H</span><span data-contrast="none" xml:lang="EN-US">aving first been described in 2009</span><span data-contrast="none" xml:lang="EN-US">, the syndrome often goes unrecognized; increased physician a</span><span data-contrast="none" xml:lang="EN-US">wareness can inform the evaluation, diagnosis, and education of patients presenting to the ED with undifferentiated allergic reaction.</span></p>
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<fieldset><legend>References</legend>
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<span data-contrast="none" xml:lang="EN-US">Further Reading:</span></p>
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<span data-contrast="none" xml:lang="EN-US">Khoury JK, Khoury NC, Schaefer D, </span><span data-contrast="none" xml:lang="EN-US">Chitnis</span><span data-contrast="none" xml:lang="EN-US"> A, Hassen GW. A tick-acquired red meat allergy. Am J </span><span data-contrast="none" xml:lang="EN-US">Emerg</span><span data-contrast="none" xml:lang="EN-US"> Med. 2018 Feb;36(2</span><span data-contrast="none" xml:lang="EN-US">):341.e</span><span data-contrast="none" xml:lang="EN-US">1-341.e3. </span><span data-contrast="none" xml:lang="EN-US">doi</span><span data-contrast="none" xml:lang="EN-US">: 10.1016/j.ajem.2017.10.044. </span><span data-contrast="none" xml:lang="EN-US">Epub</span><span data-contrast="none" xml:lang="EN-US"> 2017 Oct 16. PMID: 29074067.</span></p>
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<span data-contrast="none" xml:lang="EN-US">Crispell G, </span><span data-contrast="none" xml:lang="EN-US">Commins</span><span data-contrast="none" xml:lang="EN-US"> SP, Archer-Hartman SA, Choudhary S, </span><span data-contrast="none" xml:lang="EN-US">Dharmarajan</span><span data-contrast="none" xml:lang="EN-US"> G, Azadi P, Karim S. Discovery of Alpha-Gal-Containing Antigens in North American Tick Species Believed to Induce Red Meat Allergy. Front Immunol. 2019 May </span><span data-contrast="none" xml:lang="EN-US">17;10:1056</span><span data-contrast="none" xml:lang="EN-US">. </span><span data-contrast="none" xml:lang="EN-US">doi</span><span data-contrast="none" xml:lang="EN-US">: 10.3389/fimmu.2019.01056. PMID: 31156631; PMCID: PMC6533943.</span></p>
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