Over the past few years, an allergy to mammalian meat has been identified as a new type of food allergy presenting symptoms of delayed severe allergic reactions after consumption of red meat (beef, lamb, pork, or even kangaroo). The delayed onset of symptoms suggests a delayed release due to a possible digestion process. (CITE 13) These allergic reactions are directed against the carbohydrate galactose-α-1,3-galactose (αlpa-Gal). (CITE 3) Its molecular make up is of two building blocks from the same chemical family as table sugar, “glued” together in a 3D orientation. Alpha-gal is all-natural. You can find it in most mammals. However, monkeys, apes, and humans don’t make alpha-gal on their own. (CITE 7) But the meat allergy is found in beef, lamb, and pork, produces a hive like rash—and, in some people, a dangerous anaphylactic reaction—roughly 4 hours after consuming meat. (CITE 2) Anaphylactic shock is usually the first sign that a person has alpha-gal, and it can be extremely fatal if not treated immediately causing death by asphyxiation.
There are many of theories about where alpha gal comes from. Many people have concluded it comes from a specific type of tick (Lone Star Tick). This conclusion has been validated by reports of more Alpha-gal cases in regions with a larger population of Lone Star Ticks. Also, researchers screened hundreds of human blood samples from locations in the U.S., Africa and Central America for the antibodies against alpha-gal, and found that meat allergies are in fact more common in places where tick populations are on the rise. (CITE 17) Tick-induced allergies can result in two large local reactions, mammalian meat allergy or anaphylaxis. Large local reactions to tick bites are the least severe manifestation of tick-induced allergies. (Cite 1)
Anaphylaxis is a severe allergic reaction that can be rapidly progressing and fatal, and therefore establishing its cause is pivotal to long-term risk management. Alpha-gal has been associated with 2 distinct forms of anaphylaxis: (1) immediate-onset anaphylaxis during first exposure to intravenous cetuximab and (2) delayed-onset anaphylaxis 3 to 6 hours after ingestion of mammalian food products (eg, beef and pork). (CITE 4) Cetuximab is a chemotherapy drug used to treat colon, head, and neck cancers. All reported cases of hypersensitivity reactions to cetuximab have been in adults, in keeping with the use of this monoclonal Ab. (CITE 12) Studies strongly suggest that tick bites are a cause, if not the only significant cause, of IgE Ab responses to alpha-gal in the southern, eastern and central United States. (CITE 11)
People who live in the southern and central areas of the United States may face a higher risk of meat allergy linked to lone-star tick bites than people in other parts of the country. (CITE 16) The University of Virginia is deep in the heart of lone star tick country. It’s also home to a world-class allergy research division, headed up by immunologist Thomas Platts-Mills. He’d been hearing tales of the meat allergy since the ’90s—people waking up in the middle of the night after a big meal, sweating and breaking out in hives. But he didn’t give it much thought until 2004, when he heard about another group of patients all suffering from the same symptoms. (CITE 8) Specific one 1 pt, 1 tick and region. “Why would someone think they’re allergic to meat when they’ve been eating it their whole life?” Dr. Erin McGintee,an allergist who has reportedly seen 200 cases of this type of red meat allergy among people in Long Island, NY. (CITE 6) After all it is strange for an allergy like this to suddenly appear. Researchers don’t know yet how long after the tick bite the allergy can last. (CITE 19) However, it seems to vary from person to person. Right now, they don’t believe that it’s chronic. However, it is known that additional tick bites can bring the allergy back even if it becomes inactive. (CITE 19) Repeated exposure to tick bites can also worsen the severity of a reaction. Those who developed more Alpha-Gal antibodies from more exposure to ticks saw the most serious symptoms. (CITE 14) Mild to severe symptoms include hives or skin rash, nausea, stomach cramps, indigestion vomiting, diarrhea, stuffy or runny nose, sneezing, headaches, asthma, and, of course, anaphylaxis.
Lifestyle choices such as owning a cat can affect how people get alpha-gal, and if it causes them to get alpha-gal again then it can affect the severity of their symptoms.
One study shows that Alpha-gal sIgE was positively associated with pet ownership in both dog and cat owner, particularly, cat ownership. The alpha-gal epitope is also present in cat IgA, a monoclonal antibody found in cat dander, cat exposure has not been associated with allergic reactions. However, patients with the alpha-gal allergy have shown positive skin and blood tests to cat IgA. (CITE 18) Alpha-gal sIgE positivity was strongly associated with a history of tick bites. So this provides researchers with a direction that alpha gal comes from ticks which can be found on cats and dogs. (CITE 5)