D2.305 - Alpha-gal syndrome

Delayed allergy to meat from non-primate mammals is characterized by the late onset of allergic symptoms, between 2 and 6 hours after ingestion of meat or mammalian products, and is mediated by specific IgE against the oligosaccharide α-gal (galactose-α-1,3-galactose).

This syndrome triggers IgE-mediated anaphylaxis, gastrointestinal symptoms, and/or skin reactions.

Alpha-gal sensitization occurs through parasitic infections, most commonly tick bites, when the immune system produces IgE antibodies against alpha-gal present in the parasite’s saliva. The exact prevalence is unknown.

A 39-year-old male from Cuba, presented 3-4 hours after the ingestion of beef, lamb or pork, generalized urticaria with oropharyngeal pruritus and, on some occasions, a sensation of pharyngeal obstruction for the past 3 years. 

He tolerates sausages, chicken and turkey meat, as well as jellies and cow’s milk.

Symptoms began after being bitten by a tick. 

The initial reaction occurred after ingestion of cow’s heart.  Comorbidities: mild intermittent rhinitis with sensitisation to dust mites. Subclinical sensitisation to dog epithelium. Non-immunological hypersensitivity to NSAIDs.

Prick tests and blood tests (total and specific IgE, baseline tryptase, and ALEX) were performed.

Meat skin prick tests were performed; only chicken was positive. 

Baseline tryptase (5.95 μg/L), total IgE (148.10 IU/mL), and specific IgE against α-gal (22.30 kUI/L) were requested. 

ALEX: positivity to der f 1, der p 1 and tyrophagus.

Alpha-gal syndrome is a rare clinical condition characterized by α-gal sensitization and may manifest as a delayed food allergy following consumption of mammalian meat and exposure to drugs, vaccines, or medical products containing α-gal. Tick bites are considered an important pathway of sensitization. There is no cure; however, avoiding exposure to alpha-gal and preventing future tick bites may lead to resolution of symptoms.

Currently, pathogenesis of alpha-gal syndrome is not fully understood.