This weekend marks the unofficial beginning of summer for many in the northern hemisphere. With summer, we get more glorious sunshine, but also pesky bugs. Although most bugs are harmless and even beneficial to our natural world, some have become synonymous with debilitating diseases.
Familiar tick-borne illnesses, for example, include Lyme Disease, Rocky Mountain Spotted Fever, and Babesiosis. And, as recently as 2009, a new one has been added to the ongoing list -- alpha-Gal red meat allergy. Coming to the scene with a rising number of cases, it is not yet considered a reportable disease and many details about its pathophysiology are still unknown. Also, this alpha-Gal red meat allergy is challenging the existing paradigm of food allergies.
“Alpha-Gal” is the common term used for a syndrome associated with an IgE allergy to red meat (beef, pork, lamb, bison, venison, sheep, cows, or anything with hooves on four legs) due to a reaction to the mammalian oligosaccharide, galactose-alpha-1,3-galactose. In other words, the tick transmits the “alpha-Gal” sugar molecule into the bloodstream, which elicits the reaction. Interestingly, new research indicates that people with blood type B or AB are less likely to experience this allergy since the molecular structure of alpha-Gal is similar to that of the B antigen possibly protecting those who have the antigen from developing the allergy.
Reactions after eating meat can range from minor complaints to dangerous reactions often associated with other serious allergies. This range of response is not typical of most food allergies where one would have an immediate anaphylactic reaction. Many actually experience a delayed reaction after eating mammalian meats.
Also, although considered a “red meat allergy”, this condition isn’t simply associated with BBQs and meat eaters. Patients given the colon cancer drug cetuximab also experienced immediate anaphylactic reactions in 2006, due to it containing alpha-Gal.
This hypersensitivity reaction seems to be predominant in the southeastern region of the United States. The distribution of these antibodies first became clear by examining the specific states in which cetuximab reactions were occurring (Virginia, North Carolina, Tennessee, Arkansas, Oklahoma and Missouri). Later, the syndrome of delayed anaphylaxis to red meat became common in these same states. The connection to tick bites became more clear when the similarity between the regions for cetuximab reactions and Rocky Mountain Spotted Fever cases was noticed. Soon thereafter, it became clear that tick bites were the primary cause of the IgE antibodies to alpha-Gal, specifically the Lone Star tick (A. americanum). This is because ticks contain alpha-Gal and after a bite, the human immune system makes antibodies to this invader as protection; thus after consuming meat it is these antibodies that go into action against alpha-Gal. This mechanism differs from other tick-borne illnesses typically caused by infection.
Some speculate the difference between immediate and delayed onset between other IgE allergies and alpha-Gal has to do with the metabolic process of lipid digestion and time to enter circulation. While some people experience severe symptoms, others may experience itching, hives, congestions, lightheadedness or even GI issues that have not previously been associated to the consumption of mammalian meat. This is especially confusing since unlike “typical” allergies, many do not experience these symptoms with every exposure, making it even harder to make the connection.
Painting an even more puzzling picture of alpha-Gal, preliminary research has found a possible link between alpha-Gal allergy, atherosclerosis and increased risk of heart attack and stroke. Although the study suggests further investigation, researchers found that the quantity of arterial plaque was 30% higher in the alpha-Gal sensitized patients versus the non-sensitized patients, making them more susceptible to heart attack and stroke.
One of the biggest unanswered questions is why is meat allergy on the rise today since the Lone Star tick is not a new arachnid on the scene? Some say the alpha-Gal originates from the blood it derives from other animals, or perhaps the tick itself. Shahid Karin, a vector biologist at the University of Southern Mississippi suggests it may not come from either, but rather from the tick’s microbiome, which, if evolving, could yield a higher amount of alpha-Gal to which humans are exposed.
There are different thoughts on necessary dietary changes and considerations once diagnosed with alpha-Gal. While red meat can trigger these reactions and must be avoided, other animal proteins such as poultry and fish do not. Those with alpha-Gal will have IgE responses to beef, pork, and lamb but not to chicken, turkey, or fish (or duck, quail, ostrich and emu!). Some sources also advise avoiding milk or milk products depending on symptoms while others suggest leaving dairy in the diet while avoiding only high fat dairy products such as ice cream.
This condition is much trickier than just avoiding meat and milk since many seemingly safe products are made from these products. Like other allergies, cross-contamination in restaurants must also be avoided. Those affected should be aware than some medications and supplements are derived from animal products and could cause a reaction. Anyone affected should check with their pharmacist to ensure they are not unknowingly consuming animal-byproducts or call manufacturers to avoid unnecessary exposures. Some sources are less likely to cause symptoms but those with this allergy need to be aware that seemingly harmless foods like jelly or other desserts many contain gelatin from animal sources. Sometimes vegetarian products (think refried beans) are cooked with animal products making them a risk. It is imperative to read all labels and question ambiguous terms such as “flavor” if it is not specified since it could be a trigger.
Depending on the severity of a reaction, over-the-counter antihistamines can be used, but those with severe reactions should ask their doctor about an EpiPen while being diligent about alerting friends and family to possible emergency scenarios. This new allergy still has many unknowns and often presents differently among those who have it, requiring each person to identify their own triggers.
Some measures to prevent tick bites include avoiding wooded bushy areas, wear protective clothing when outside, and performing thorough tick checks. Awareness of the risk of allergic reaction to red meat should be considered by anyone recently bit by a Lone Star tick.
Related Biotics Research Products: