Mammalian Meat Allergy

What is Mammalian Meat Allergy?

Mammalian Meat Allergy (MMA) is a relatively newly recognised allergy, believed to be caused by being bitten by a paralysis tick. Being bitten by a paralysis tick doesn’t always mean you will develop MMA, but the allergy doesn’t

appear to develop in people who haven’t been bitten by a tick. The connection between tick bites and developing MMA was discovered by Sydney allergy/clinical immunology specialist, Associate Professor Sheryl van Nunen. A person with MMA can experience a mild reaction through to a severe and life-threatening anaphylaxis after eating mammalian meat (some people with MMA will also react to products derived from mammals such as milks, dairy products and gelatine). MMA can develop months after a tick bite, and the initial tick bite does not need to cause an allergic reaction for MMA to develop. Some people are allergic to ticks and then develop MMA, but others who are not allergic to ticks may be bitten by a tick and then still go on to develop MMA. The severity of the tick bite reaction does not indicate who will or will not develop MMA after a tick bite.

What are mammalian meats?

Mammalian meats include beef, pork, lamb, rabbit, kangaroo, goat, and venison. Poultry, such as chicken, turkey, duck, and quail, is not mammalian meat as these meats come from birds. Seafood that includes fish, prawns and oysters is also not mammalian meat. Crocodile is another meat that is not from a mammal, but a reptile.

Why is MMA different to other food allergy?

Unlike other food allergy, which is caused by the protein in the food, the MMA allergen is a carbohydrate called alpha-galactose (alpha-gal), which is found in meat from all mammals (except humans, great apes and old world monkeys).

Most food allergic reactions happen within a few minutes to 2 hours of ingesting the allergen. A reaction due to MMA generally occurs several hours after eating the meat (often 2–10 hours later). Many people with MMA will wake up in the night with symptoms of an allergic reaction after having eaten dinner containing mammalian meat many hours earlier.

How can you prevent MMA developing?

If you live in an area that has ticks, which is the whole of the east coast of Australia (including about 20–30 km inland from the coast) and parts of Western Australia (specifically Denmark, WA) it is important to try to avoid getting bitten. This can be easier said than done of course. There are a number of ways to prevent tick bites from occurring, including wearing long-sleeved tops/shirts, long pants tucked into long socks, and a wide-brimmed hat. Using a DEET or Picaridin-based insect repellent can also be helpful (look for these words on your insect repellent).

If you have a tick bite, the best way to prevent MMA developing is to remove the tick according to the instructions from TiARA (Tick induced Allergies Research and Awareness). This includes using permethrin cream to kill small ticks, or freezing larger ticks with an ether-based spray, such as Tic Off®, and then letting the tick drop off—remember, freeze, don’t squeeze! Removing a tick is best left to an expert and should be done with fine-tipped forceps—remember, household tweezers are tick squeezers! Watch this video for instructions on how to remove a tick

What should I include in my first aid kit if I live in an area with ticks?

If you live in or visit an area that has ticks, it is a good idea to include in your first aid kit an ether-based spray, such as Tic Off®, and a permethrin cream, such as Lyclear®. As described above, by using the ether spray to kill adult ticks and the permethrin cream to kill the nymph or larval ticks, this allows the ticks to be killed while still attached to the skin. If you are not confident about safely killing and removing the dead tick (if it doesn’t fall off by itself), consult a medical specialist or hospital emergency department.

Getting diagnosed with MMA

It is important to see a clinical immunology/allergy specialist if you feel you may have MMA (or any other moderate to severe allergy). The allergy specialist will take a history and ask whether you have had a tick bite and other allergic reactions, and check what you ate and when you ate before you had your allergic reaction. A blood test may also be done to help confirm the diagnosis.

How can you manage MMA once you have been diagnosed?

Like any food allergy, the only way to avoid an allergic reaction is to avoid the trigger. It is also important to be prepared for a reaction by having your adrenaline (epinephrine) injector (such as EpiPen®, Anapen®) and ASCIA Action Plan for Anaphylaxis with you at all times. The trigger in this case is any form of mammalian meat. It is therefore also important to make sure that any food products, medicines or vaccines you take do not contain gelatine. Some people with MMA also need to avoid mammalian milk such as cow’s, goat, and camel milk. A&AA worked with TiARA to develop a MMA allergen card that outlines the most common sources of alpha-gal that people with MMA need to avoid.

MMA is the only food allergy where we know why it has developed (i.e. a tick bite has occurred in a susceptible individual). If you develop MMA and are bitten again by a tick at any of its life stages, you can increase your allergy level. If you develop MMA and don’t get bitten again, your allergy level can drop significantly over 18 months to 2 years and some people can return to eating mammalian meat after 3–4 years without any tick bites. Tick bite prevention is key, so treat your backyard, dress for the occasion and kill the tick where it is!

Eating out with Mammalian Meat Allergy

A&AA also worked with TiARA to develop a chef card specifically for people who have MMA. You can present this card to the wait staff when you order your meal so that they understand what is required to prepare you a safe meal. As always, be prepared for an allergic reaction by carrying your adrenaline injector (if prescribed) and having your ASCIA Action Plan with you. For more information about tick allergies go to:

www.tiara.org.au

www.allergyfacts.org.au/allergy-anaphylaxis/food-allergens/mammalian-meat-allergy

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