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Potentially life-threatening emergency
Alpha-gal syndrome
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Potentially life-threatening emergency

Alpha-gal syndrome

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Contributors: Paritosh Prasad MD
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Synopsis

Tick bites from some Amblyomma and Ixodes (and possibly Haemaphysalis) species have been associated with the subsequent development of IgE antibodies to alpha-gal (galactose-alpha-1,3 galactose), a mammalian oligosaccharide. Presence of IgE antibodies to alpha-gal is associated with two distinct forms of anaphylaxis in the United States, Europe, and Australia.

Individuals with elevated IgE titers to alpha-gal have experienced symptoms of urticaria, angioedema, and/or anaphylaxis immediately or 3-6 hours (delayed onset) after ingesting mammalian meat (eg, beef, pork). Implicated tick bites have been noted to be associated with pruritus for 2 or more weeks.

The other reaction seen in patients with IgE to alpha-gal is an immediate onset of anaphylaxis during first exposure to intravenous cetuximab, an epidermal growth factor receptor (EGFR) inhibitor used for the treatment of colorectal cancer, metastatic non-small cell lung cancer, and head and neck cancer.

A blood test for these IgE antibodies exists.

Delayed diagnosis and treatment of anaphylaxis of any cause predicts poor prognosis. Immediate management involves removal of the triggering allergen if possible, epinephrine by intramuscular injection, and further evaluation and management.

IgE to alpha-gal has been identified in some sub-Saharan African populations where it is thought to be due to exposure to cestodes, nematodes, scabies, ticks, and a variety of other ectoparasites. Interestingly, however, there have been no reports of delayed anaphylaxis upon exposure to red meat in this population.

Codes

ICD10CM:
T78.40XA – Allergy, unspecified, initial encounter

SNOMEDCT:
419076005 – Allergic reaction

Look For

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

Best Tests

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Management Pearls

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Therapy

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Drug Reaction Data

Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.

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References

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Last Reviewed: 09/28/2017
Last Updated: 10/06/2017
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Potentially life-threatening emergency
Alpha-gal syndrome
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Alpha-gal syndrome : Tick bite, Urticaria
Copyright © 2019 VisualDx®. All rights reserved.