September 13, 2018
2 min read

Red meat allergies may develop after chigger bites

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There is an established link between Lone Star tick bites and red meat allergy, but chiggers — or the Trombiculidae mite — may be another source of immunoglobulin E antibodies that contribute to this allergy, research published in The Journal of Allergy and Clinical Immunology:  In Practice suggests.

According to the researchers, chiggers bite hosts only while they are in the larval phase. Preferring high humidity, the insects commonly bite humans on the legs and waistline, and they focus on areas where the epidermis is thin. The bites of chiggers are not painful. However, the bites can cause grouping of popular and papulovesicular lesions that can result in erythema and pruritus. Itching can begin hours after a bite and can resolve within 72 hours. The lesions may last for 1 to 2 weeks.

“If a patient comes in telling me they ate red meat for dinner and then hours later woke up with anaphylaxis, I suspect an alpha gal allergy,” Russell Scott Traister, MD, PhD, assistant professor of pulmonary, critical care, allergy and immunologic diseases at Wake Forest Baptist Medical Center, said in a press release. “With those symptoms, doctors usually ask if the person has had a tick bite recently. But we started seeing patients with the same symptoms who said they had not had a tick bite, only chigger bites.”

Studies have previously linked alpha-gal sensitization and tick bites, including bites from the Lone Star tick (Amblyomma americanum), Ixodes ricinus, I. holocyclus, A. cajennese, A. sculptum and Haemaphysalis longicornis.

Traister and colleagues examined the cases of three patients who presented to Wake Forest Baptist Medical Center with allergic reactions, including urticaria, swelling, diffuse hives, and oropharyngeal edema requiring epinephrine, following consumption of mammalian meat. Two of the three patients had no history of food allergy or atopic disease. All patients had been bitten by an estimated 50 to 200 chiggers.

The researchers’ clinical suspicion led them to test these patients’ alpha gal levels. All patients had elevated levels alpha gal IgE.

One patient had previously been bitten by four to five Lone Star ticks 2 months before being bitten by chiggers. However, the patient was able to consume mammalian meat without an allergic reaction.

The researchers wrote that in a questionnaire given by the University of Virginia to 311 people with alpha-gal sensitivity, nearly all (n = 301) had tick or chigger bite exposure within the past decade. A small portion — 5.5% — had no tick bite exposure.

“In the meantime, we want allergists to be aware that patients may report chigger bites and, based on that fact alone, should not dismiss alpha-gal sensitization as a possible diagnosis,” Traister said. – by Katherine Bortz

Disclosures: The authors report no relevant financial disclosures.