By Laurie Ross
A mysterious allergy has been appearing in allergists’ offices. People report symptoms that act like food allergy – hives, itching, stomach upset, even anaphylaxis – but they happen hours after finishing a meal; standard skin prick tests are negative; and many people affected have no personal or family history of allergy.
Putting the clues together, allergists at the University of Virginia began to see a pattern. Detailed questioning revealed patients had a recent tick bite that itched longer than normal – 10 days or so. Also, symptoms were triggered by food from mammals: beef, pork, lamb, goat meat – even dairy products for some.
Many questions remain, but the condition now has a name: red meat allergy – also called “alpha-gal” after the blood carbohydrate involved.
To find out more, Allergy & Asthma Today caught up with allergist and immunologist Scott Commins, MD, PhD, one of the first at the University of Virginia to research this allergy mystery. Dr. Commins is currently an associate professor at the University of North Carolina Thurston Research Center.
AAT: What’s the most important thing the public needs to know about red meat allergy?
This is a delayed reaction: It happens hours after eating a meal. That’s so different from a typical food allergy. People often don’t think it’s a food-allergic reaction.
AAT: What symptoms should you watch for?
Itching and hives, as you might typically expect – it’s especially noticeable on hands and feet. However, we are seeing increasing numbers of patients who have gastrointestinal issues (such as heartburn, diarrhea and abdominal cramping) without any hives or itching and this makes it a challenge to suggest food allergy as the diagnosis.
The tick bite itches longer than usual. Some people talk about a hard knot under the skin at the site of the bite.
The allergy can cause anaphylaxis – a life-threatening allergic reaction that involves more than one organ system at a time – but this is rare. It does happen, but the overwhelming majority of people get hives, itching or upset stomach.
AAT: If you get a tick bite, should you automatically avoid meat for a while?
No. The chances of getting red meat allergy are still quite low. We’re doing studies to identify the groups at highest risk. Largely it’s hunters, gardeners and others who spend a lot of time outdoors in tick areas.
If you get a bite and it hangs around and is itchy – and later you experience unusual symptoms like stomach problems or hives (but not fever, headache, or joint pain, which indicates more of a tick-borne illness), that’s when I’d stop eating meat until you can get tested.
AAT: Does the species of tick matter?
No, this is worldwide – it’s not just triggered by the lone star tick, as some have suggested. There are cases reported in Germany, Sweden, Australia – and there are different species of ticks in all these locales. The data suggests it’s not about one particular kind of tick.
AAT: Can you trigger the allergic response through cross contamination with a serving spoon, or kissing someone who has just eaten a burger?
Many patients are okay as long as they don’t eat a major cut of meat – they can tolerate milk and dairy and casual contact. Others become extremely sensitive to all mammalian products. Some of these patients tell me they can’t even take a capsule that has gelatin in it. It’s a goal for us to try to figure out why this happens, as they appear to be the ones at highest risk of anaphylaxis.
AAT: Is this a life-long condition?
The condition does not appear to last forever. However, additional tick bites can boost your level of sensitivity, so if you’re someone who goes outdoors and gets tick bites 4-5 times a year, it may be hard for this to go away. Others may be fine within 20-24 months. However, the allergy could return with another tick bite.
What to do if you think you might have red meat allergy?
Find an allergist who is knowledgeable about meat allergy, as it requires special testing. Normal skin prick testing tends to come back negative, but researchers at the University of Virginia developed a blood test that can identify the allergy; it’s available throughout the United States and Europe.
Meat allergy is a potentially life-threatening allergy, so anyone diagnosed with it should carry two epinephrine auto-injectors at all times in case of accidental exposure.