The Mammalian Meat Allergy, Ticks, and the Importance of Avoiding Mold

by Dr. Susan Tanner, MD

For many years, Rocky Mountain Spotted Fever and Lyme disease have been recognized as illnesses associated with tick bites.  In each of these diseases, particular bacteria in the ticks themselves are the culprits and are contracted when these bacteria are released into the body from a tick bite.  Fast forward to 2009, when another phenomenon associated with tick bites was discovered.

A series of patients presented with allergic symptoms of many manifestations following the ingestion of mammalian animal flesh; this includes cow, bison, deer, lamb, and pork.  The sugar, commonly known as alpha-gal, is found in all mammals except for Old World monkeys, apes, and humans, as well as some other organisms. Some patients experienced full-blown anaphylactic reactions with swelling of the airways and great difficulty breathing. Others had severe gastrointestinal symptoms (nausea, vomiting, diarrhea), and still others with skin manifestations, like hives and rashes.  Most of these patients had no prior history of allergy to these meat products so the sudden presentation of the symptoms made the syndrome difficult to pin down initially and to tie to the ingestion of meat.

A series of studies conducted both at Mayo Clinic and at the Cleveland Clinic found that this allergy was actually to the alpha-gal sugar/carbohydrate, not to a protein.  As mentioned earlier, all of these mammals contain a sugar/carbohydrate molecule called galactose-alpha-1 galactose or Alpha-gal, which humans do not have.  So, in essence, the reaction occurred after eating the animal products, but was not so much to the meat itself but to the Alpha-gal molecule contained in the meat.  How could this happen in someone who grew up eating beef, pork and lamb and never had a problem? Enter the lone star tick!

Tick saliva from Ixodes Ricinus, also referred to as the lone star tick, has been associated with the development of Alpha-gal Syndrome (AGS), as it can interfere with the maturation and migration of specialized antigen-presenting dendritic cells.  Dendritic cells are central initiators of allergic responses to conventional protein allergens, presenting the allergens to naive T cells and creating a microenvironment that pushes T cells toward a pro-allergic T-helper (Th) 2 response. In the case of dendritic cells exposed to Ixodes Ricinus saliva, this exposure provokes these dendritic cells toward development of allergic-type response almost entirely rather than a more balanced immune system response.

The most common areas of reports of Alpha-gal diagnoses in the United States are in the Southeastern part of the country, but the incidence, much like that of Lyme disease and Rocky Mountain spotted fever, is spreading rather rapidly, as the mammals on which these ticks live migrate from one area to another, in response to environmental pressures, population spread and other factors.  While initially the disease was seen primarily among forestry workers and hunters, it has become more common in urban settings. Alpha-Gal illness has not reached the levels of Lyme disease, but it is definitely on the rise.

The severity of the illness varies but it always follows the ingestion of mammalian products and, for some sufferers may include milk products as well. It does appear to require the bite of the tick to occur (some data also suggests chigger bites can trigger the response); anyone who has consumed meat or milk products has been exposed to the alpha-gal carbohydrate as they are in all of these products, but it is BLOODBORN sensitization from the tick saliva that sets the reaction/syndrome off.

Alpha-Gal Diagnosis

Diagnosis can be tricky but may be suspected any time there is sudden allergic reactivity to meat or milk products.  A chemotherapy drug called Cetuximab also can cause reaction in patients who have been rendered allergic by the tick. Serum Immunoglobulin E reaction to Alpha-gal is usually helpful in identifying this culprit.  Patients who have received animal heart valves can develop sudden sensitivity to these as well, necessitating replacement with a mechanical part if tick bitten and Alpha-gal results.

A few other observations have been made, primarily that individuals with blood types A and O may be most susceptible, while blood type B may be less at risk of developing the disorder.   The vast majority of sufferers are male.  Subsequent tick bites by lone star ticks may worsen the reactions significantly to the point of being life threatening. Organ meats, such as liver, heart and kidney may induce an even stronger allergic response than consuming the flesh, likely due to the increased concentration of Alpha-gal in these products.  Animal byproducts, such as gelatin, can also induce the allergic response.

This chart from the linked article in The International Journal of Molecular Sciences shows the incidence and frequency of symptoms:

Common Symptoms and Symptom Distribution in Study Participants with AGS (n = 15)a

Organ System Presentation Percentage (Number Out of 15)
Cutaneous Urticaria (hives), pruritus, angioedema 93% (14)
Gastrointestinal Emesis, diarrhea, gastroesophageal reflux, abdominal pain, abdominal bloating, 73% (11)
Respiratory Respiratory distress, dyspnea, coughing, chest tightness, wheeze, hypoxia 33% (5)
Oropharyngeal Throat itching, throat constriction, neck tightness, mouth/throat swelling 26% (4)
Cardiovascular Syncope, pre-syncope 13% (2)

Adapted from Iweala OI, Choudhary SK, Addison CT, Commins SP. T and B Lymphocyte Transcriptional States Differentiate between Sensitized and Unsensitized Individuals in Alpha-Gal Syndrome. Int J Mol Sci. 2021;22.

Treatment Options

There is no traditional treatment for Alpha-gal syndrome as of now.  Over time, and with no subsequent tick bits, symptoms may lessen or completely abate, but the amount of time needed as well as the percentage of people who become totally asymptomatic is yet to be determined.  Prevention strategies must include protective clothing and repellants when in and around areas in which ticks are likely.  Alpha-gal illness does require that the tick actually bite as it is the transfer of tick saliva into the blood stream that causes the problem.  I would surmise that the longer the tick is adhered, the more risk of the onset of Alpha-gal syndrome.

As a physician, thus far, I have only had two patients with this disorder.  Neither had developed life-threatening reactions but in an abundance of caution they are both quite vigilant about anything they consume or even use topically that may contain any mammalian animal byproducts. Because there is a lot of stimulation to mast cells, another proponent of allergic response, anything that can help to lower mast cell reactivity may lessen the chances of severe anaphylactic response, which brings us around again to having that clean air, clean water, clean food!

Low dose antigen immunotherapy holds promise for treatment, as does low dose naltrexone to modulate the T cell response. I simply have not had enough patients myself to have a good handle on how well these therapies work but feel that they both have potential of offering help with low risk.

Final Notes

In researching this article, it does appear that this is a world-wide issue, including areas as far away as Norway and South Africa.  I believe there is still so much to learn about the transmission and etiology of this strange and troubling disorder.

Additionally, the reason for my writing this particular article for a website focused on mold illness and sinusitis is this–cross-reactivity, when the body’s immune system identifies the proteins in one substance (e.g., mold) and the proteins in another (e.g., a beef) as being similar. When the person contacts either one, the immune system may create allergy-like symptoms and mast cells may be activated in a way that becomes particularly problematic. Symptoms of mold illness can vary from hives to respiratory distress, which means some symptoms also overlap with Alpha-Gal Syndrome. Plus, since both conditions may involve reactions to products or foods that previously caused no reaction, misdiagnoses of both of these conditions are possible. If you think you have either of these illnesses, as always, do whatever you can about ensuring that you are breathing clean, mold-free indoor air, and ask your healthcare provider for a component blood test to home in on ruling out Alpha-gal. I also encourage my most sensitive mold patients–especially those with Mast Cell Activation Syndrome or histamine intolerance and who seem to not be able to tolerate many supplements to also consider Alpha-gal as it could be another layer in peeling back the onion toward total recovery and better health.

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