“The allergist I have here in town thinks I am *overreacting*. You mean, overreacting when my neighbors next door are cooking their meat on the grill and when I walk outdoors and the fumes hit me, it feels like I have been snatched up by the throat and I start having trouble breathing. …There are days I am afraid to even leave my house. But I have to earn a living, otherwise I will not have a house…. I already had to quit one job because of Alpha Gal. My job was right next door to a restaurant and their pot roast night and burger nights made it impossible for me to keep that job, as the fumes wafted over into my store… I live in a constant state of apprehension and fear, because I like to breathe. This allergy threatens to take that and my life away from me, every time I walk out my front door.”
This is a quote from a patient living with severe alpha gal syndrome, a rare form of acquired allergy to the consumption of mammalian meat. The allergy is acquired through the bite of a tick. While cases of this syndrome have been reported in many regions across the world, the true prevalence and impact of alpha gal syndrome remains unknown. Patients are forced to avoid consuming any red meat or meat from mammals (pigs, cows, lamb, etc.). However, there is a lot of variability in how patients are impacted; a report from the US Department of Health and Human Services acknowledges that in general, the unusual condition remains under-researched, and misdiagnosis or delayed diagnosis is all too common.
Disease Mechanism
The disease is the result of an allergic response to galactose-alpha-1, 3-galactose (alpha gal), a carbohydrate that naturally occurs in all mammals except for apes, humans, and old world monkeys. Many species of ticks are not particularly selective in their host. Alpha gal is transferred to humans by a tick that has previously fed on another type of mammal, such as a deer; the body responds to the foreign substances with a rush of IgE antibodies, leading the symptoms of an allergic reaction next time alpha gal enters the body.
The Lone Star Tick
In the US, alpha gal syndrome is most closely linked to the lone star tick (Amblyomma americanum). This tick is so named for the white dot present on the back of adult females; males have smaller white spots or streaks on their backs instead. The species is expanding its range, which means that cases of alpha gal syndrome in the US are likely to increase as more people are bitten.
Alpha Gal Syndrome: Not Your Typical Allergy
Alpha gal is one of the first known food allergies triggered by a carbohydrate and not a protein; it is also unusual in that symptoms are often delayed by several hours after the consumption of meat or other mammalian products. Patients often display symptoms of anaphylaxis, indicating a severe and potentially life-threatening allergic reaction; it can be especially dangerous for patients with asthma. Symptoms include skin reactions such as hives, scaly skin, and severe itching; swelling affecting the airway, tongue, face, lips, and other areas; headaches, shortness of breath, and runny nose; sneezing, and gastrointestinal problems such as abdominal pain, nausea, and diarrhea.
Sensitivity to the allergy is varied; in some patients, lean meat such as venison doesn’t trigger a reaction; in others, merely being in the presence of cooking meat can cause symptoms. While avoiding mammalian meat is important for all patients, some may need to avoid dairy products as well to prevent reactions. In some cases, the allergy appears to wear off over time, with some patients recovering in about five years; however, there are also cases in which another tick bite leads to the reappearance of symptoms. It is still unclear how the tick bite itself causes the reaction to begin.
Issues
Alpha gal syndrome patients face many hurdles common to other rare and poorly known diseases, such as lack of awareness in the medical field and among the general public. Diagnostic delays and misdiagnosis are routine as alpha gal behaves differently than most other food allergies. As doctors are not required to report cases, the number of affected individuals is unknown. Clearly more research and awareness is critical to account for the needs of this patient group.
Click here to learn more about alpha gal syndrome.
