August 07, 2018
2 min read

IgA antibodies from tick bite may lead to red meat allergy

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The bites of Lone Star ticks can influence the amount of immunoglobulin A antibodies related to alpha gal a patient may have. An allergy to alpha gal, or mammalian meat allergy, may contribute to many cases of anaphylaxis in teens and adults that would have otherwise been labeled as idiopathic.

“Of the 218 cases of anaphylaxis we reviewed, 33% were from alpha gal,” Debendra Pattanaik, MD, associate professor of medicine at the University of Tennessee Health Science Center, said in a press release. “When we did the same review in 1993, and again in 2006, we had a great many cases where the cause of the anaphylaxis could not be identified. That number of unidentified cases dropped from 59% in 2006 to 35% in this report, probably because of the number of identified alpha gal cases. Our research clearly identified alpha gal as the cause of anaphylaxis in the majority of cases where the cause was detected.”

Pattanaik said that the second leading cause of anaphylaxis was food allergy, which accounted for 28.2% of anaphylaxis cases.

The researchers conducted this retrospective study in their private, university-affiliated allergy and immunology clinic and included patients treated between 2006 and 2016. Of the 281 possible cases of anaphylaxis observed during the study period, 218 met criteria for the condition. Patient ages ranged from 9 to 78 years, and over half (64%) were female. Pattanaik and colleagues noted that only four patients were younger than 13 years old, and most (73.4%) were diagnosed with concomitant atopic disease.

Image of lone star tick
Lone star tick bites may be the cause of many cases of anaphylaxis that were previously thought to be idiopathic, according to researchers from the University of Tennessee Health Science Center.
Source: CDC/James Gathany

Definitive causes of anaphylaxis were observed through history and testing in 39% of patients, with nearly one-third of these cases attributable to alpha gal (n = 28; 32.9%). All remaining cases had a probable etiology (26.1%) or idiopathic causes (34.9%).

When alpha gal was not related to the case, anaphylaxis was caused by venom (18.8%), exercise (5.9%), systemic mastocytosis (5.9%), medications (4.7%) and other causes (3.5%). Shellfish, peanuts, tree nuts, fish and milk were the most commonly reported food allergies.

The researchers wrote that when probable causes were considered, food was most likely choice (35.1%). Alpha gal (26.3%), medications (22.8%), other causes (10.5%), and venom (5.3%) were also frequently considered.

Nearly all patients (96.3%) had allergies that resulted in skin manifestations. Additionally, respiratory symptoms (68.3%), neurologic symptoms like syncope or presyncope (53.2%), gastrointestinal symptoms (37.2%) and cardiovascular symptoms (20.2%) were also common.

“We understand that Tennessee is a state with a big population of Lone Star ticks, and that might have influenced the large number of alpha gal cases we identified,” Jay Lieberman, MD, vice chair of the American College of Allergy, Asthma and Immunology, said in the release. “The Lone Star tick is predominantly found in the southeastern U.S., and we would expect a higher frequency of anaphylaxis cases in this region would be due to alpha gal. However, the tick can be found in many states outside this region, and there are already more cases being reported nationwide.” – by Katherine Bortz

Disclosures: Pattanaik reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.