Enjoy burgers? Better use tick repellent.
The lone star tick continues to be common across a wide swath of this region, and a bite can give you an allergy to red meat.
June 28, 2022
A bite from a tiny, pesky bug can prevent you from ever enjoying another hamburger or steak.
For years, there has been a growing awareness that the lone star tick’s range was increasing and its bite can lead to an allergy to red meat.
A study being led by Kevin Liu, MD, assistant professor of Clinical Medicine, shows that more than 400 patients are being followed by VUMC’s allergy clinics due to a red meat allergy caused by Galactose-alpha-1,3-galactose, which is, understandably, shortened to alpha-gal. This molecule is a carbohydrate molecule found in mammalian meats, most commonly cow, lamb and pork.
Hives, swelling of the lips, eyes, tongue, throat, respiratory issues, vomiting, diarrhea, increased heart rate and low blood pressure are common reactions to alpha-gal.
The ticks feed on deer, and then when they bite humans, the humans are exposed to the Galactose-alpha-1,3-galactose found in the deer blood still in the tick. The human’s immune system then develops molecules call “IgE” that are specific to the “alpha gal” allergen. Once this occurs, people are prone to have allergic reactions.
Hives, swelling of the lips, eyes, tongue, throat, respiratory issues, vomiting, diarrhea, increased heart rate and low blood pressure are common reactions to alpha-gal.
Alpha-gal syndrome was only completely described 13 years ago, and has recently come more into focus as more doctors learn about the symptoms.
“Overall, alpha-gal seems to be fairly stable recently,” said Cosby Stone, Jr. MD, MPH, assistant professor of Medicine in the Division of Allergy, Pulmonary and Critical Care Medicine,, who sees alpha-gal allergic patients as part of his practice.
“I suspect that we have caught up to some degree on all of the people who were unaware that they had this allergy, and that folks are much more aware that it exists and are less likely to go for long without a diagnosis,” he said.
As more patients are treated and clinicians learn more, some nuances of alpha-gal are becoming evident.
The main treatment is avoidance of the foods or products that a patient reacts to (usually meats are most common) and avoidance of further tick bites.
“Further tick bites are the main thing that we know of that will make a patient more allergic to alpha-gal,” Stone said.
“Treatments beyond avoidance need to be studied, but there seems to be a role for antihistamines and other allergy treatments in some patients who frequently get hives which also started around the time they got alpha-gal.”
As more patients are treated and clinicians learn more, some nuances of alpha-gal are becoming evident.
“A good example was a recent case reported in the New York Times featuring my colleague Dr. Basil Kahwash, where the patient’s main complaint was hives that never went away,” Stone said.
“We have also begun to recognize that every now and then there are patients who have alpha-gal and they only have gastrointestinal symptoms, usually abdominal pain and diarrhea,” he said.
Beyond the different presentation of symptoms, which varies by patient, it’s also true that most people are able to tolerate medications with mammal products, dairy foods and gelatin, while a smaller number of others are more highly allergic.
Some patients become less allergic to alpha-gal over time, and some do not, for reasons that researchers would love to understand but don’t yet.
One thing that’s evident is that even someone who gets better with time can suffer a tick-borne relapse.
“We have seen patients who got ‘better’ in that their allergy antibody levels went down and they stopped reacting to alpha-gal containing foods, but another tick bite brought the whole thing — antibodies and symptoms — right back again,” Stone said.
Some people, knowing the consequences of a tick bite, might be tempted to just avoid outdoor activities altogether.
From a health perspective, this is not a good idea, Stone said.
“What I do advise is careful tick avoidance and use of permethrin-containing camping sprays — which you can spray on your outdoor clothes, let them dry on a line overnight and then it’s good for five washings,” he said. “The sprays can help to kill ticks on contact and prevent bites.
“Some of my patients do alter their habits, though, because they know that certain places that they used to go are the places where they will get ticks. So, instead of walking through the forest, they will walk on trails or tracks.
“There are too many good health reasons to spend time outdoors, and I don’t want my patients to miss out,” he said.
photo by iStock
