Mammalian Meat Allergy

Mammalian Meat Allergy is a delayed allergic reaction triggered by eating the meat of some mammals.   The condition was discovered by researchers at the University of Virginia only a few years ago.  Their findings of this new allergy were published in 2009.  The allergy initially was confined to the southeastern part of the U.S. with a majority of the cases in Virginia.  Subsequently, the condition has become more widespread.
Mammalian Meat Allergy is initiated by a bite from a Lone Star Tick (Amblyomma americanum), named because of its distinctive small white mark on its back.  Many people deny a tick bite and instead say there were bitten by chiggers (a type of mite), even though chiggers do not cause the allergy.  For this reason, it is prudent that an allergist ask the patient if they have ever been bitten by a tick or a chigger.   In susceptible individuals, the bite sets off a chain reaction which results in the formation of an IgE antibody (the “allergy” antibody) that attaches to a carbohydrate (sugar) present in the meat of only mammals called galactose-alpha-1,3-galactose (also known as “alpha-gal”).  This is present in mammalian meat such as beef (cow), pork (pig), lamb (sheep), venison (deer), rabbit, goat, bison, whale, etc.  It is also important to point out that for people who travel to exotic locations, one must be aware that there are other mammals that are eaten which contain alpha-gal.  Some of these mammals include horse, dog, cat, squirrel, guinea pig, kangaroo, and whale, to name a few.  Since fish, shellfish, and poultry (i.e., chicken, turkey, duck, quail) are not mammals; they do not have alpha-gal.

In this condition, unlike a typical food allergy, the symptoms usually do not start for several hours (typically 3-6 hours) after the consumption of the offending meat from a mammal.  In more common food allergies like peanut, tree nut, fish, and shellfish allergies, symptoms usually begin in less than one hour after exposure to the food.  When a person who harbors this antibody eats the meat from mammals, it causes release of histamine and other chemicals which are responsible for allergic reactions.  The symptoms can include itching, rashes, hives, swellings of lips, tongue and other soft tissues, abdominal pain, nausea, vomiting, and diarrhea.  In severe instances, it can also lead to life threatening anaphylactic reactions resulting in difficulty in breathing, drop in blood pressure, dizziness, and loss of consciousness.  In summary, the person will develop delayed anaphylaxisangioedema (swelling), and/or urticaria (hives).

If you have experienced any of the above symptoms, please call Black & Kletz Allergy and request to see one of our board certified allergists at any one of our 3 locations in Northern Virginia and Washington, DC.  We can confirm or rule out the condition by taking a complete history, performing an examination, and obtaining a blood sample.  Avoiding meat from mammals and in severe cases limiting the intake of dairy products can prevent serious and dangerous adverse reactions.