Transcript: Tick Bites, Meat Allergies, and Chronic Urticaria
Tick-bite induced meat allergies are really unlike any other food allergy we know. The most interesting feature of the reactions may be that first symptoms can occur hours after eating meat. Normally if you have an allergic reaction to a bee sting or something, it happens within minutes. With this, you could have a piece of bacon for breakfast and your throat doesn't start closing off until the afternoon, and so you blame lunch, or doctors just call it “‘spontaneous’ or ‘idiopathic’ anaphylaxis." Ideopathic is just doctorspeak for we have no idea what the cause is.
Delay is because the alpha-gal is thought to be absorbed along with the fat in meat, given that the allergic reaction occurring four to five hours after meat ingestion corresponds to the peak absorption time of fatty acids from the intestinal tract.
And what makes it even more difficult to diagnose is that the majority of victims experience only occasional overt reactions, despite regular meat consumption. Fattier meats like pork rinds may provoke episodes more consistently and severely, but it's not like it happens every time.
And it's on the rise. Ten years ago we didn't even know this thing exists, but now in tick-ridden states, as many as 20% of the population have these anti-meat allergic antibodies, and more and more people are coming in affected, though probably no more than 10% who test positive go on to experience hives or serious allergic reaction to meat.
We're also seeing it more and more in kids, researchers in Virginia finding it not uncommon, though identification of these cases may be straightforward. Unlike in adults, who frequently present with systemic reactions, the majority of children with this syndrome present with just skin manifestations, such as hives. Doesn't mean it's not serious. In fact, nearly half the kids ended up in the ER, and about 1 in 12 needed to be hospitalized.
Up to a quarter of the population breaks out in hives at some time in their lives, but some children can be affected for weeks or months. And it can be triggered by infections, foods, drugs, parasites, or autoimmune, but in a large subset of cases we don't know what the trigger is, and so, call it chronic idiopathic urticaria. It's a common thing pediatricians see, and the only cure is avoiding and eliminating whatever's triggering it, but in three-quarters of cases we have no clue.
But now we know that many children who had been diagnosed with mysterious hives or allergic reactions, and may have been specifically told that the reactions were not a result of a food allergy, may have actually been suffering from alpha-gal meat allergies. Given the serious nature of the reactions and the rising frequency of allergic swelling and hives across all age groups, this underscores the importance of identifying what's going on, and clearly physicians should keep this new diagnosis in mind.
Allergies to red meat might be more common than previously thought. 2% would means millions of people, but just to put this in context, Americans are much more likely to suffer an anaphylactic reaction due to seafood, tick bite or not, no matter where they live. A national survey of emergency rooms found shellfish was by far the most frequently implicated food, and unlike many other allergies, kids don't tend to outgrow fish and shellfish allergies.
And many fish allergies are actually allergies not to the fish, but to worms in the fish, like anisakis. Exposure to these parasites, living or dead in fish is a widespread problem. In fact, you can even have an allergic reaction to the parasitic fish worm eating chickens that were fed on fishmeal. This is one of the ways someone who's allergic to fish could get triggered by chicken. Reminds me of pork-cat syndrome where your mouth can get all itchy eating bacon in people with cat allergies, because of an allergic cross-reaction between catskin and pig blood proteins.
Anisakis worms are found particularly in cod, anchovies, and squid, and can also cause chronic hives and intractable chronic itching.
Because of these worms, researchers recommend people stop eating seafood sushi altogether because besides inducing allergenic reactions, the worms may cause a leaky gut syndrome, which often is unrecognized and it can predispose to other, more important pathologies than just being itchy all over.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.
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