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Expert provides insight on alpha-gal red meat allergy

HOUSTON — Alpha-gal syndrome, a type of red meat allergy, was first identified in Australia in 2006 and has become increasingly prevalent in the United States and worldwide.

Previous studies found that bites from certain ticks can influence the immunoglobulin E antibodies related to alpha-gal in humans, causing the allergy.

Michael Levin, MD, head of the division of asthma and allergy at the University of Cape Town, South Africa, discussed the characteristics unique to alpha-gal during a presentation at the American College of Asthma, Allergy & Immunology Scientific Meeting.

The unusual features of alpha-gal originally made the allergen difficult to identify, Levin explained. For instance, anaphylaxis occurred hours after ingesting meat and the symptoms are nonatopic.

 

Alpha-gal syndrome, a type of red meat allergy, was first identified in Australia in 2006 and has become increasingly prevalent in the United States and worldwide.

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In addition, patients with alpha-gal have different types of reactions. Although many experience classic symptoms of anaphylaxis, one subgroup, Levin said, experiences only gastrointestinal symptoms like severe heartburn and abdominal cramping.

Another unusual characteristic of alpha-gal is its wide geographic variation. The association between tick bites and the condition is one explanation for this, Levin said.

For instance, the Lone Star tick has been found to transmit alpha-gal in the United States, and cases in humans have been found frequently in regions where the tick is found. Other types of ticks were found to transmit alpha-gal in other parts of the world, but not all ticks can transmit the condition, Levin explained.

While ticks were originally believed to transmit the disease passively by biting an animal with alpha-gal and later biting a human, recent studies have shown that transmission may occur directly from the tick to humans.

Levin noted that recent studies demonstrated a relationship between tick exposure and reactivity, and a relationship between tick sensitization and alpha-gal sensitization, and findings have provided additional evidence that ticks cause alpha-gal in humans.

One study, he explained, found that patients who had more tick bites have higher concentrations of alpha-gal IgE antibody.

“This is really good evidence that ticks are directly causative,” Levin said.

Another study, which evaluated alpha-gal in forestry workers, found that alpha-gal–specific IgE waned over time in those who did not have additional tick bites, and in some patients who did have an additional tick bite. However, other patients who had additional tick bites experienced dramatic increases in IgE.

“This does have some implications in terms of outgrowing the reaction to alpha-gal, and it also holds some interesting ideas for the possibility of therapy,” Levin said.

Despite recent findings, there are still many questions about the disease, Levin said. More research is needed to determine if there are more vectors responsible for sensitization to alpha-gal, identify the pathways involved in sensitization and eliciting the reactions, and discovering preventive or curative strategies. – by Erin Michael

Reference:

Levin, M. Alpha-gal: A fascinating and evolving story. Presented at: American College of Asthma, Allergy & Immunology Scientific Meeting; Nov. 7-11, 2019; Houston.

Disclosures: Levin reports no relevant financial disclosures.