alpha-gal syndrome

^[1]^[2]^[3]^[4]

Etiology

see lone star tick
suspected cases predominantly occurred in counties within the southern, midwestern, & mid-Atlantic U.S.^[2]

developmennt of allergy to galactose-alpha-1,3-galactose (alpha-gal)
tick saliva may contain alpha-gal obtained from other mammals on which the tick has fed
exposure to alpha-gal containing tick saliva then triggers development of alpha-gal specific IgE antibodies in humans
once sensitized, consumption of red meat triggers hypersensitivity

most common:
- pruritus or urticaria (70%)
- gastrointestinal symptoms (40%)
- angioedema
- contact urticaria of the oral mucosa
- anaphylaxis
other
- presyncope or syncope
symptoms are delayed in onset, often 3-6 hours after eating*
- patients have awakened from sleep with allergic symptoms or anaphylaxis after eating red meat for dinner

* lipids are absorbed into the gut and circulation more slowly than proteins

↑ Rothaus C Hunting for a Diagnosis NEJM Resident 360. Feb 3, 2021 https://resident360.nejm.org/clinical-pearls/hunting-for-a-diagnosis
↑ ^2.0 ^2.1 Thompson JM, Carpenter A, Kersh GJ, Wachs T, Commins SP, Salzer JS. Geographic Distribution of Suspected Alpha-gal Syndrome Cases - United States, January 2017-December 2022. MMWR Morb Mortal Wkly Rep 2023;72:815-820. Jyly 28. PMID: https://www.ncbi.nlm.nih.gov/pubmed/37498787 https://www.cdc.gov/mmwr/volumes/72/wr/mm7230a2.htm
↑ ^3.0 ^3.1 Carpenter A, Drexler NA, McCormick DW, et al. Health Care Provider Knowledge Regarding Alpha-gal Syndrome - United States, March-May 2022. MMWR Morb Mortal Wkly Rep 2023;72:809-814. July 28 PMID: https://www.ncbi.nlm.nih.gov/pubmed/37498792 https://www.cdc.gov/mmwr/volumes/72/wr/mm7230a1.htm
↑ Centers for Disease Control & Prevention (CDC) Alpha-gal Syndrome (AGS) 2022 Case Definition https://ndc.services.cdc.gov/case-definitions/alpha-gal-syndrome-ags/