Galactose-alpha-1,3-galactose or alpha-gal is a carbohydrate molecule present in all mammals except Old World monkeys, a class of mammals including humans. This sugar is present in animals like cows, sheep, pigs, rabbits, and deer. It is not present in birds, reptiles, fish, and humans.
Normally, it is not a threat to people that regularly consume meat. However, the number of people with an alpha-gal allergy has risen from 12 in 2009 to 34,000 in 2019. This number is expected to rise in the future following the climate change pattern.
The first alpha-gal allergy was reported in 2002 in the USA. Alpha-gal allergy syndrome (AGS) is not congenital or autoimmune. It is an acquired allergy that usually develops in adulthood primarily due to a Lone Star tick bite.
Lone Star ticks feed on animals like rodents, pigs, and dogs. When the lone star tick bites you, it transmits alpha-gal molecules to the blood through its saliva. An immune reaction is initiated against the elements of tick saliva, and sometimes, the body produces IgE antibodies against alpha-gal. Now the next time you eat red meat that contains alpha-gal, you will experience a delayed allergic reaction. Read on to know how to treat an alpha-gal allergy.
The road to the detection of AGS is a very interesting story and critical for some AGS sufferers.
In 2002, a group of scientists in America observed that some cancer patients would react adversely to a cancer drug known as cetuximab. Blood tests were conducted, showing the presence of antibodies against the alpha-galactose epitope that was also present in cetuximab. This was puzzling information because humans do not typically produce this antibody since alpha-gal is a common element in our diet (from red meat).
During the same time, many cases of red meat allergy were popping up in people who had been spending significant amounts of time outdoors, mostly in southern states. Their serum tests also revealed IgE antibodies against alpha-gal. Upon inspection, it appeared that the groups of people with red meat allergy and cetuximab allergy were geographically overlapping.
In the following years, additional research and data concluded that people that spent more time outdoors, especially in the southeastern states were contracting tick bites, leading to the production of alpha-gal antibodies. This would manifest as red meat allergy in some people and cetuximab allergy in cancer patients.
If you have cancer and have developed AGS, let your doctor know so that your medication can be adjusted accordingly.
Until recently, Lone Star ticks were mostly found in the southeastern states. With climate change, ticks have been progressing northward, too. Most commonly in Texas, they can also be found from the midwest to the east coast. They can be identified by a white (star-shaped) spot on the dorsal shield of the female tick.
Mammals with red meat contain alpha-gal. It is found in their meat, organs, fluids, and by-products. The list of meat/animals that can trigger AGS includes:
Additionally, animal products may also contain traces of alpha-gal. Not all AGS sufferers may not respond to these products but some can have fatal reactions. This includes products like:
Cetuximab, the cancer drug, can also trigger a delayed allergic reaction in people with AGS.
Usually, food allergies occur on exposure; a person may break out with typical signs of allergy within minutes of consuming common allergens like peanuts, shellfish, etc. However, symptoms of AGS appear more than three hours after alpha-gal intake (from any of the sources mentioned above). This is why it is called delayed red-meat allergy.
One of the reasons why AGS was overlooked until recently is the delay between allergic symptoms and red meat consumption. A sudden bout of hives and sneezing is not usually attributed to a meal consumed four hours ago.
AGS is diagnosed by an allergist or healthcare specialist by conducting blood tests to identify the presence of alpha-gal IgE antibodies in the blood. An allergy skin test may also be done in which a small amount of alpha-gal is placed under the skin. A rise in histamine level within a few hours shows a positive AGS test.
A differential diagnosis for alpha-gal allergy can be pork-cat syndrome. The symptoms are very similar, however, the onset of the reaction is immediate. In true alpha-gal syndrome, the allergic reaction occurs more than three hours after eating red meat.
Ticks can be a nuisance – they’re tiny and can hide in human skin and hair. You should try your best to prevent tick bites.
You can avoid AGS symptoms by maintaining a diet with minimum consumption of:
In 2020, the FDA approved the genetic modification of pigs so that alpha-gal is absent from their products. If you suffer from AGS and enjoy pork, you may safely consume pork that is developed under the GalSafe trademark.
Since allergic reactions usually trigger the release of histamine locally or generally in the body, an antihistamine is the most effective alpha-gal allergy treatment. Antihistamine medication is readily available over the counter, such as Benadryl (diphenhydramine). An intense reaction like anaphylaxis must be treated with epinephrine. Your allergist will most likely prescribe an EpiPen for this purpose.
A small study in 2020 suggested that Omalizumab may help AGS symptoms. According to the findings, 86% of patients in the study reported an improvement in symptoms after being exposed to mammalian food products by accident or on purpose. You may discuss the use of Omalizumab with your doctor if you have AGS.
The biggest complication in having any allergy, food or otherwise, is the risk of anaphylaxis. It is a swelling of the airways causing restriction and narrowing which prevents free breathing. It can lead to losing consciousness and if not treated immediately, can result in death.
AGS is an acquired allergy from a tick bite that causes adverse bodily reactions when eating red meat. A delayed response occurs after three to six hours of eating mammalian products. You should document any symptoms you have to explain to your doctor so they can provide the best diagnosis and alpha-gal allergy treatment. With your doctor, you can discuss the lifestyle changes and medication you will need to prevent a dangerous and possibly fatal reaction.
If you think you have AGS, book an appointment with Family Medicine Austin for your diagnosis today! We have practitioners that perform skin tests and prescribe an alpha-gal treatment plan to improve your quality of life.