Comorbid conditions associated with time to, severity of alpha-gal reactions
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Key takeaways:
- Autoimmune diseases correlate with the severity of alpha-gal reactions.
- Patients with asthma and mast cell disease were more than twice as likely to have a reaction within 5 minutes of exposure.
SAN ANTONIO — Symptom patterns in alpha-gal syndrome suggest concurrent diseases such as autoimmune disease and vitamin D deficiency, according to data presented at the American Academy of Allergy, Asthma & Immunology Annual Meeting.
“We wanted to look at the relationship between time and severity and underlying medical conditions,” Jennifer Platt, DrPH, adjunct professor, University of North Carolina Gillings School of Global Public Health, told Healio. Platt coauthored the study with Tina Merritt, MD, FAAAAI, of the Allergy & Asthma Clinic of Northwest Arkansas.
The researchers administered a 60-question online survey via snowball sampling to more than 2,500 respondents with alpha-gal syndrome, asking them about additional medical conditions including vitamin D deficiency as well as asthma, type 1 and 2 diabetes, mast cell disease, rheumatoid arthritis and thyroid disease.
Also, the researchers asked participants about any anaphylaxis, tongue swelling, turning blue, fainting or loss of consciousness or cardiac arrest that they experienced.
“We picked the symptoms that we considered to be severe,” Platt, who also is the cofounder and director of Tick-Borne Conditions United, said. “Those do go across different body systems.”
Compared with other allergic reactions to food, 221 of the respondents said they had experienced reactions due to alpha-gal syndrome within 5 minutes of exposure, with 37.56% of them also reporting asthma and 47.06% of them reporting a vitamin D deficiency.
Also, 1,016 of the respondents said their reactions occurred within the typical window of 4 to 6 hours after exposure, which the researchers said was consistent with previous observations of delayed responses in alpha-gal syndrome. These participants included 23.23% with asthma and 33.56% with a vitamin D deficiency.
Autoimmune diseases correlated with alpha-gal reaction severity, the researchers said. For example, 15.48% of participants with osteoarthritis, 6.01% of those with rheumatoid arthritis and 18.21% of those with thyroid disease reported severe symptoms.
Among patients with asthma, 29.33% reported severe alpha-gal symptoms, and 13.21% reported non-severe symptoms, prompting the researchers to note that asthma appeared to correlate with the severity of the reaction.
Patients with vitamin D deficiency reported severe symptoms in 39.53% of cases and non-severe symptoms in 20.05%, indicating that it appeared to correlate with the severity of the alpha-gal reaction as well.
Concurrent diseases also impacted the frequency of alpha-gal reactions. Specifically, 30.2% of participants with asthma, 8.24% of those with type 2 diabetes, 9.8% of those with mast cell disease, 20% of those with osteoarthritis, 5.1% of those with rheumatoid arthritis, 18.43% of those with thyroid disease and 41.96% of those with vitamin D deficiency were more likely to have one or more reactions each week.
When the researchers compared patient reported times to reaction with underlying conditions, they found that the respondents with autoimmune disease and vitamin D deficiency were twice as likely to have an alpha-gal reaction within 5 minutes.
For example, 8.24% of respondents with type 2 diabetes, 20% of those with osteoarthritis, 5.1% of rheumatoid arthritis, 18.43% of those with thyroid disease and 41.96% of those with vitamin D deficiency were twice as likely to react within 5 minutes.
Participants with asthma (37.56%) and mast cell disease (9.8%), meanwhile, were more than twice as likely to have a reaction within 5 minutes.
“Across the board, vitamin D deficiency was an issue,” Platt said. “Whether they’re having immediate reactions or very long-term reactions, after hours and hours, vitamin D deficiency was an underlying condition.”
The researchers additionally noted a significant association between quicker reaction times and lower alpha-gal IgE totals (P < .0001). However, test positivity did not correlate with the severity of the reaction.
“Historically, you think, lower score, less reactive,” Platt said. “Here, lower score, more reactive, more likely to react within 0 to 5 minutes.”
Overall, the researchers said that the clinical presentation of alpha-gal syndrome varied with symptoms reported across all body systems.
“The alpha-gal experts will say that alpha-gal is consistently inconsistent,” Platt said. “Nothing is predictable.”
Platt also said that the source of alpha-gal sensitivities remains debatable. While many cases are attributable to tick bites, she continued, 20% of the respondents did not remember getting bit — which is not the same as saying that there was no bite.
“There are some other emerging theories that maybe pet dander can trigger it,” she said. “We have some people that have gotten stings, and then realized they had it. So maybe there’s an underlying presence and then it gets triggered with that stimulus.”
In the United States, researchers have isolated the alpha-gal carbohydrate in the Lone Star tick as well as in the black legged tick, also known as the deer tick.
“That’s the one that causes Lyme disease,” Platt said. “I don’t like to call it the deer tick because people think that it’s just on deer, and it’s not.”
Platt noted that she has met a growing number of people with Lyme disease who cannot tolerate red meat and who are unaware that they possibly have alpha-gal syndrome.
“That’s a problem,” she said.
Considering these findings, the researchers advised providers to be aware of the spectrum of symptoms and understand that multiple factors may contribute to the severity of reactions.
“Unlike other allergies, we found that patients with quicker reaction times, eg, less than 5 minutes, were significantly more likely to have a low-IgE blood test result,” Platt said. “The research also shows that underlying factors such as autoimmune conditions and vitamin D deficiencies can contribute to the severity of reactions.”
The researchers plan on continuing their work as well.
“The survey remains open, and we will continue to explore relationships between symptoms, reactivity, lab results and underlying conditions,” Platt said.