The hidden danger of stepping outside
I spend significant time outdoors in the pursuit of hobbies like bushwalking, through-hiking, rock climbing, and even for work. Wilderness areas are, naturally, dangerous. Far from humanity's attempts to build a perfectly safe and comfortable environment, you'll likely encounter wildlife that — under the wrong circumstances — may threaten you with a bite, envenomation, or other physical trauma. The earth itself also offers several dangers. One might find themselves spraining an ankle, risking dehydration, or plummeting to their death from a high cliff. Having said that, I wouldn't give up the great outdoors for anything. As with any activity, risks can be managed effectively reducing the chances of injury or death to vanishing odds. One risk I never expected to encounter was losing the ability to eat the meat of mammals.
The lone star tick (Amblyomma americanum). Source: Center for Disease Control and Prevention
I knew it existed, I even came to know a few people afflicted with the condition all of whom work or study in a similar field to myself. Known commonly as red meat allergy or mammalian meat allergy (MMA), the condition is more specifically an allergic reaction to galactose-alpha-1,3-galactose (alpha-gal). Alpha-gal is a sugar found in the muscle tissue of all mammals except old-world monkeys and apes, that includes us and our closest living relatives – the chimpanzee. Oddly enough I developed this condition after I had suffered many tick bites over about a year. Yes, that's right, tick bites are the culprit1. I do not know if it was one unlucky bite or the result of cumulative bites as at the time I was spending a significant amount of time laying in the dirt digging up dung beetles, in addition to hiking as often as I could. That year I got as many as six tick bites, possibly more that I didn’t catch.
An engorged female paralysis tick (Ixodes holocyclus). Source: Australian Museum
It is not just field biologists that need to be concerned, the paralysis tick (Ixodes holocyclus), according to the Australian Department of Health, accounts for 95% of tick bites in eastern Australia. Joining the paralysis tick’s ranks is Ixodes (Endopalpiger) australiensis, recently having been implicated in a case of MMA2. It is not just a risk in Australia either, in America the lone star tick (Amblyomma americanum), in Europe Ixodes ricinus, and in Panama Ixodes cajennense are known to cause MMA. In fact, cases have now been recorded in 17 countries2. Ticks already get a bad rap for being creepy little bloodsuckers who can cause numerous illnesses such as Lyme disease; as if they needed this on top of it all.
In addition to being spread and contracted, MMA is a unique allergy due to the delayed onset of symptoms after exposure. For most food allergies symptoms have an onset of seconds to minutes – think the stereotype of peanut allergy sufferer ballooning up for comedic effect — however for MMA symptoms typically manifest four or more hours after ingestion of mammal meat. Despite the delayed onset, symptoms of MMA are similar to those of other food allergies ranging from gastrointestinal discomfort, rash and hives, to full-blown anaphylactic shock.
The results of self experimentation. Source: me and my body
Because of the delay between exposer and the manifestation of symptoms, it can be rather difficult for those afflicted to make the association between their medium-rare steak and an uncomfortable night on the toilet or worse in the hospital. In my case, I had prior knowledge of the condition so I suspected that the intestinal pain I experienced after eating meat may be due to an allergy. Still, I went ahead and performed an experiment as follows. Several hours after enjoying beef meatballs for dinner I noticed my usual symptoms creeping up, hives where I had previously been bitten by ticks and intestinal pain, so I went ahead and ate the leftovers. Luckily I didn't suffer anaphylaxis, just a painful and sleepless night. Despite this evidence, I still opted to visit an allergy specialist to get blood work confirming my self-diagnosis. Now it should go without saying, I absolutely do not recommend anyone tries the approach I described above. Self-experimentation, especially related to life-threatening medical conditions, should never be attempted – for obvious reasons. Always go see a doctor if you suspect you might have MMA and if you're experiencing symptoms of anaphylaxis get emergency help immediately.
While MMA sounds like a scary consequence of stepping into the bush I do not wish to discourage people from getting outdoors. Many people experience dozens of tick bites and never develop the condition and tick bites can be prevented effectively with the use of repellents and protective clothing. Furthermore, those who do develop MMA can easily manage the risk of exposure by avoiding red meat in their diet. So excuse the overly dramatic title and go out and explore!
Van Nunen SA, O’Connor KS, Clarke LR, Boyle RX, Fernando SL. An association between tick bite reactions and red meat allergy in humans. Med J Aust. 2009.
Kwak M, Somerville C, van Nunen S. A novel Australian tick Ixodes ( Endopalpiger ) australiensis inducing mammalian meat allergy after tick bite . Asia Pac Allergy. 2018. doi:10.5415/apallergy.2018.8.e31