Alpha-gal Diagnosis

After a lifetime of no allergies at all, I have been officially diagnosed with “alpha-gal” or alpha-galactose syndrome–a somewhat rare (but maybe not!) condition where the body sometimes has a severe, delayed immune reaction to red meat, for several years following a tick bite.

Ticks who have bitten a non-human mammal, such as a cow, deliver a meat-based sugar called alpha-galactose (full name: Galactose-alpha-1,3-galactose) in their saliva. The immune system, in properly reacting to the many foreign substances in tick saliva, also treats alpha-galactose (α-gal) as an unwelcome agent. This then leads to a cross-reaction to digested read meat (but not always, which makes it so hard to diagnose). That’s how I can eat the equivalent of multiple herds of cattle for decades with no problem, then start reacting badly to beef.

Unlike traditional food allergies, which kick in fast and furiously soon after consumption, the α-gal reaction is not to a protein, but to a sugar released in meat digestion. In fact, this is the first food “allergy” known to be related to a non-protein molecule, and the first known to cause delayed reactions. This is because meat digests slowly. As such, the sugar isn’t released in substantial amounts right away, and reaction can be delayed 3-6 hours, sometimes 8. The substance is found in all non-primate mammals (cattle, buffalo, deer, horse, rabbit, squirrel, dog, cat, etc.)–but not humans or other primates. Technically, I can be a reaction-free cannibal…but, no thanks! Alpha-gal also appears in the cancer drug Cetuximab, which cannot be taken; I hope not to have that need. Birds, fish, and amphibians do not have α-gal.

In my case, I’ve had hundreds of red-meat meals over the years since the first reaction, but only a few episodes. This has included some huge steaks with no reaction at all. Figuring how often I’ve had red-meat-based meals (and it’s been a lot), I’ve calculated that the reaction has happened around 1 out of every 110 times I’ve eaten beef as a main course. Alpha-gal reaction can (but hasn’t yet) progressed fully to life-threatening anaphylaxis. In two cases, Benadryl pills (and in two others, ER trips with injected Benadryl and steroids) have quelled these episodes.

Four α-gal urticaria (hives) reactions have hit in 12 years, accompanied by varying degrees of intense itching, nausea, and minor swelling of ears and throat, but only this year was it diagnosed by specialists at the Oklahoma Allergy Clinic. Fortunately for me, but not for him, one of their specialists actually has this problem–and has become a leading expert on it. Skin tests yielded no reactions to anything (including red meat); but now a blood test is available to confirm it. I’ll have yearly testing of antigen levels that I hope will drop enough at some point to get back to eating big, juicy steaks. ‘Til then, only occasional small nibbles (BLTs are no problem), otherwise no red meat at all…

The bad news: I’m supposed to avoid red meat for an unknown time (months to years) until antigen levels come down. The good news: in most cases, if tick bites are avoided, α-gal antigens decline and tolerance for red meat eventually returns. The other good news: one who has this disorder can eat all forms of non-mammal meat (poultry, seafood, frogs, snake, etc.) with no problems at all. I also have never reacted to dairy, and still consume it often and with no trouble, though some alpha-gal patients do have intense reactions. Small amounts of well-cooked red meat (i.e., a slice of bacon or a bite of red meat) also cause no reaction for me. Apparently, more intense and thorough cooking does help in some cases.

If you have been bitten by the lone star tick, you are susceptible. If you develop hives or anything else resembling an allergic reaction of unknown cause (outside any common pollen reactions of course), and ever have been bitten by a tick, log your foods during the prior 12 hours and see an allergist. If you suspect this, have your doctor order an “Alpha-gal IgE test” of a blood sample.

The α-gal disorder probably has been around as long as people have had bites from the Lone Star tick, but wasn’t identified until the last seven years, following a paper by Cheryl van Nunen and a self-discovery of the problem by famous UVa allergy professor Thomas Platts-Mills (who got bitten by many ticks, then had a severe reaction to beef). His unit has studied this condition most extensively. If you want to read a good scientific paper on the topic, see their study, “Delayed anaphylaxis, angioedema, or urticaria after consumption of red meat in patients with IgE antibodies specific for galactose-α-1,3-galactose“. Media stories, as usual for scientific topics, have overgeneralizations, missing facts and flat-out wrong information, so stick to the medical experts.


Leave a Reply

You must be logged in to post a comment.