Ticked Off: How a Single Tick Bite Can Give You Severe Food Allergies

The 2017 summer forecast is in: Ticks galore.

The Northeast is set to have more ticks this summer than it has seen in years. Some are even calling the oncoming population explosion the “tick apocalypse.” That’s a bit of an exaggeration, but the upcoming increase in tick numbers is no joke.

We have a variety of factors to blame for this impending tick season. One of them is something I discussed in one of the first articles I wrote for this blog, the masting of oak trees. Sometimes oak trees enter what is known as a mast year and produce a bumper crop of acorns. Many animals eat the acorns, including mice. With so much food, mouse populations surge following a mast year. Just like mice feed off the acorns, ticks feed off mice, so rising mouse populations set the stage for future increases in tick numbers too. We had an oak mast year in the autumn of 2015. 

As if the mouse menace wasn’t enough, we also had a very mild winter this year, making conditions even more favorable for ticks. More ticks mean more tick bites upon humans, and unfortunately, more incidents of tick-borne diseases.

The most widely publicized disease you can get from a tick bite tends to be Lyme disease (May is in fact Lyme Disease Awareness Month), and for a good reason. Lyme disease can be very uncomfortable in the short term, and in the rare cases where Lyme becomes chronic, it can lead to a lifetime of discomfort, or even disability. Ticks can carry a number of other diseases as well, so it is incredibly important this year to protect yourself (click here for recommendations) if you are going anywhere that ticks might live, like wooded areas or places with long grass. 

Do you, like me, hate bug spray but love hiking? If the possibility of Lyme disease isn’t enough to convince you to take precaution against ticks, there is one more factor you should consider…


An Ominous Mystery

This particular tick-induced ailment is very uncommon, but can change lives dramatically when it strikes. The people who encounter this issue usually don’t notice right away. Maybe they know they’ve been bitten by a tick recently, maybe they don’t. Maybe they go on a course of antibiotics to prevent Lyme disease, but antibiotics do nothing to help you avoid this particular phenomenon.

It may take as long as six months for symptoms to appear. The first sign that something is amiss might be stomach cramping, or maybe a breakout of hives.  Some people have even more severe responses, like anaphylaxis. These symptoms can emerge during the day, but sometimes they attack in the middle of the night, seemingly detached from any possible trigger.

The combination of ambiguous symptoms and time delay of onset can mean that a long time elapses before people suffering from this ailment go to a doctor, and receiving a proper diagnosis often takes another few years. When they do finally realize how their body has changed, it can be shocking, even devastating.

What has happened is that they’ve developed an allergy to the alpha-gal carbohydrate. Simply put, they’ve become allergic to red meat.


The Red Meat Allergy

They can eat the fries, but not the burger. Image by the Home Chef India.

They can eat the fries, but not the burger. Image by the Home Chef India.

When a person has an alpha-gal allergy, their immune system becomes hypersensitive to a carbohydrate called galactose-alpha-1,3-galactose, or alpha-gal. This is a molecule found in the meat of almost all mammals. The only ones that don’t produce it appear to be apes and a subset of monkeys. Humans, being apes, are among those that don’t naturally have alpha-gal in their bodies. Birds, fish, and other non-mammals are alpha-gal-free as well.

When someone with an alpha-gal allergy eats a hamburger, or a nice slab of steak, it sets an allergic reaction in motion. However, what makes this allergy baffling and tough to pin down is that symptoms often don’t appear for 3-8 hours after meat is consumed. This gives the allergic reaction a seemingly random nature, and people often don’t realize that the reason they can’t breathe now is that they ate some bacon half a day ago. 

There is no single symptom that everyone with an alpha-gal allergy experiences and the allergic reactions can range from mild to life-threatening. Up to 70% of suffers experience respiratory symptoms during an episode. Skin reactions like hives or itching can also occur. Others may just have gut cramps, sometimes severe, or other gastrointestinal issues like vomiting or diarrhea. Many of us, if we had to rush to a toilet after eating a plate of barbecue, would assume it was food poisoning rather than some new bizarre allergy causing us pain. 

So why do people develop these red meat allergies after a tick bite, and what options are available for those who do?



Why?

The exact mechanism of developing a red meat allergy remains unclear, besides that it occurs after being bitten by a tick. However, researchers have developed some hypotheses about what might be going on.

When a tick bites an animal, it burrows its barbed mouthpiece under the skin so it can draw up blood. If an animal is already infected with Lyme disease or any other pathogen, it can pass that infection on to the tick, which then acts as a carrier and can spread the disease to other animals it bites, like humans. Just like a tick can transfer bacteria, it’s highly likely that it’s transferring other particles from host to host, including alpha-gal.

Removing a tick within 24 hours minimizes odds of infection. Grip the tick with tweezers as close to the skin as possible.  Pull the tick out without twisting or crushing, and carefully check the bite site to make sure you removed the head. 

Removing a tick within 24 hours minimizes odds of infection. Grip the tick with tweezers as close to the skin as possible.  Pull the tick out without twisting or crushing, and carefully check the bite site to make sure you removed the head. 

Most people don’t have long-term bad reactions to tick bites, even if the bite deposits alpha-gal into their bloodstream. The immune system usually does a great job at combating invaders, like when it springs into action after a tick bite in attempt to halt the spread of disease. The mechanism for the development of an alpha-gal allergy may be a misfire of that immune response.

Scientists suspect that if alpha-gal is mixed in with bacteria and other pathogens in a tick bite, that the immune system might react to alpha-gal like a threat too. The immune system has ways of tracking what threats it has responded to previously, so if it responds poorly to alpha-gal once, it has encoded within itself the knowledge that alpha-gal is an invader and should be stopped in the future, thus setting itself up for allergic reactions upon further exposure to the alpha-gal in red meat. However, this explanation is currently purely theoretical, and future experiments may uncover a different mechanism.

Many people cut meat out of their diets by choice, but the transition can be very difficult for those who are unwillingly denied red meat by this allergy. Some people’s red meat allergies fade over time, allowing them to eat beef and pork once more. However, given that certain patients have recorded over 20 years of alpha-gal allergy symptoms, it appears that some people are afflicted for life. Products like milk and gelatin also contain amounts of alpha-gal, and those severely affected often have to cut those out of their diet as well. There is no known cure for alpha-gal allergies, leaving many cut off from favorite foods for the rest of their lives. 

Developing an alpha-gal allergy is a notably rare reaction, but it is something to be aware of nonetheless. If you are planning on doing some yardwork or going for a walk in the park and are on the fence about whether to use bug spray, you would do well to err on the side of caution. If you don’t, you could be looking at a lifetime of not being able to eat ham, bacon, and steaks ever again.

Found a tick biting you? Don't panic! See: What to do after a tick bite.

- Kate Dzikiewicz, Paul Grisworld Howes Fellow