Alpha-Gal Syndrome
Our Lone Star Tick and Alpha-Gal presentation from April 14th 2023 at the Ag Hall is now available by demand on MVTV: Video Link
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Background
Galactose-alpha-1,3-galactose, commonly known as “alpha-gal”, is a carbohydrate that is found in most mammals but not humans. Alpha-gal syndrome (AGS) is the result of a tick moving from one mammalian host, where it picks up the Galactose-alpha-1,3-galactose, to a human. When it bites the human, it transfers the alpha gal into the blood, where the immune system sees it as an antigen and begins producing antibodies. When an individual subsequently consumes mammalian meat (or sometimes even dairy products), these antibodies react to the alpha gal in the digestive system as an intruder and the individual experiences an allergic reaction, ranging from an upset stomach to hives and inflammation, and in some cases even an anaphylactic reaction. The allergic reaction generally occurs 3 to 6 hours after consumption, so AGS can be difficult to identify due to its rarity and delayed response. Lone star ticks are believed to be the major vector for AGS, however there is some evidence that other tick species, including the deer tick, may also be capable of transferring alpha gal to humans.
CDC - Products that may contain alpha-gal
Infection Development Process
The tick attaches onto a mammalian host and feeds on its blood.
The carrier tick transfers to a second host, a human, to feed on their blood.
When the carrier tick introduces alpha gal to the human body, a novel IgE antibody response activates to combat this apparently foreign invader.
This response triggers the typical allergic reactions of mucus secretion, sneezing, itching, coughing, anaphylactic shock, tear production, inflammation, vomiting and diarrhea, which are all mechanisms that expel allergenic substances from the body.
Diagnosis
It is difficult to diagnose AGS due to its relative newness in our area and the lack of reliable data for the efficacy of available testing methods. For example, skin prick tests that used extracts of mammalian meat are not dependable, and other invasive intradermal skin tests are rarely used for food allergies. Today, most doctors depend on blood tests specifically for alpha-gal IgE antibodies. One issue with current testing methods is that there is no standardized cut-off for diagnosis, so clinical authorities tend to use the cut-off of greater than 0.1 IU/mL to indicate a positive test result for AGS.
Sensitivity
The probability of alpha-gal transmission depends on the recent activity of the feeding tick since their previous host must have been a mammal whose flesh contained alpha-gal. The incidence and severity of reactions varies significantly depending on a few factors. Alcohol consumption and exercise habits may contribute to some individuals experiencing more extreme reactions than others. An individual’s sensitivity to allergies in general also appears to be related to the frequency and severity of symptoms. Additionally, higher levels of alpha-gal and fat in the consumed food can also increase the frequency and severity of symptoms.
Treatment
As of now, there is no cure for alpha-gal other than abstaining from mammalian products. Although some people have recovered from the condition, usually after being allergic for years, many individuals do not. AGS can be managed by avoiding future tick bites and refraining from consuming mammalian products. Naturally a major goal for present-day researchers is to determine reliable and efficient treatment options.
Prevalence
In 2019, over 34,000 Americans were diagnosed with AGS, up from about 12 in 2009. Doctors suggest that there may be millions of citizens who are suffering from the condition but have not yet been diagnosed. Originating in southeastern states, the presence of the lone star tick and AGS has moved up the east coast and into New England. However, it is a widespread problem and Alpha-gal syndrome has been reported on every continent other than Antarctica. The increasing frequency of alpha-gal syndrome among Americans is believed to be due to the increase of mammal products in processed foods and the growth of the lone star tick population within the country.
AGS on Martha’s Vineyard
The Vineyard is one of the latest hotspots where alpha-gal has emerged along the east coast. AGS presents itself in both children and adults. Most of those who have been diagnosed with AGS were unaware of the allergy before they began experiencing symptoms. Among the affected, reactions ranged from skin irritation, such as hives, and nausea to fainting and confusion. We are aware of one local incidences of anaphylactic shock and it is likely there have been others we are unaware of. The frequency of alpha gal is almost certain to increase as lone star ticks continue to spread and increase in numbers across the Island. It is important for individuals and healthcare professionals to recognize cases of AGS before severe reactions occur. A common theme among interviewees is that most of them performed their own investigations of AGS individually; much of the information was gained through online support groups and research articles. Some medical professionals knew to test for alpha-gal immediately, while other sufferers had to visit multiple doctors or educate their provider on the topic. Overall, more effort is needed to educate the community on this tick-borne problem and assess the prevalence of alpha-gal on the island.
This report was written by Grace Newfield and edited by Richard Johnson and Patrick Roden-Reynolds.
Grace is a Candidate for a Masters in Public Health, Health Policy and Management Program in the School of Public Health and Health Sciences, Umass Amherst.
Patrick Roden-Reynolds is the Director of the Tick-Borne Illness Prevention Program sponsored by the Boards of Health of the six island towns. Richard Johnson is Director emeritus.
REFERENCES
Please consult the references below for more detailed information. We provide the information above as a public health advisory but we are not medical professionals.
Flaherty, M. G., Kaplan, S. J., & Jerath, M. R. (2017). Diagnosis of Life-Threatening Alpha-Gal Food Allergy Appears to Be Patient Driven. Journal of primary care & community health, 8(4), 345–348. https://doi.org/10.1177/2150131917705714
New Pediatrics Study Findings Have Been Reported from University of North Carolina ('doc, Will I Ever Eat Steak Again?': Diagnosis and Management of Alpha-gal Syndrome)." Health & Medicine Week, 5 Feb. 2021, p. 469. Gale OneFile: Health and Medicine, link.gale.com/apps/doc/A650281580/HRCA?u=mlin_w_umassamh&sid=ebsco&xid=8c907d89.
Mayo Clinic - Alpha-gal syndrome
Department of Health & Human Services - Alpha-gal Syndrome Report