Hey everyone,
Being related to a bunch of ticks can make party planning hard. Take my relative, the Lone Star tick (Amblyomma americanum) for example. I wanted to throw a big, summer BBQ bash and I find out that they can cause “Red Meat Allergy”?!?!?!
Image depicts rising IgE levels in a human patient after exposure to larval tick bites. Click on image for full sized view. (Figure 2 from Commins et al. 2013)
So I did some research for you all and this is what I found out. Red meat allergy is actually a hypersensitivity reaction, aka allergy, to a molecule found in non-primate mammals (i.e. beef and pork). This molecule is called alpha-gal (long name: oligosaccharide epitope galactose-alpha-1,3,-galactose). When a human in the US is bitten by a lone star tick, their body’s immune system can produce a type of immune molecule called IgE that targets alpha-gal (Commin et al. 2013). It is unknown if the tick saliva itself, residual blood from a previous meal, or a different pathogen carried by the lone star tick is the reason for this production of anti-alpha-gal IgE (Steinke et al. 2015)
SIGNS AND SYMPTOMS OF RED MEAT (ALPHA-GAL) ALLERGY
According to Steinke et al. (2015) there have been two different clinical forms of alpha-gal allergy:
- For colorectal cancer patients with alpha-gal hypersensitivity that receive treatment with IV cetuximab, they can have an immediate onset anaphylaxis due to the anti-alpha-gal IgE molecules that their immune system is producing.
- There is a delayed onset allergic reaction that can occur 3-6 hours after consuming beef or pork products if the human’s immune system is producing anti-alpha-gal IgE molecules. This delayed response usually results in hives and swelling.
Flow chart depicting how a bite from a lone star tick can result in alpha-gal hypersensitivity. Click on image for full sized view. (Figure 3 from Steinke et al. 2015)
RED MEAT (ALPHA-GAL) ALLERGY THROUGHOUT THE WORLD???
So it turns out the US is not the only place that has to deal with ticks causing red meat allergy! In the US, we are worried about Amblyomma americanum, the lone star tick. However, over in Europe, they need to look out for Ixodes ricinus and in Australia they are worried about Ixodes holocyclus ruining their BBQs… What is weird though is that in the United States, my ticky relative the blacklegged deer tick, Ixodes scapularis is not associated with red meat allergy even though it is in the Ixodes genus (Steinke et al. 2015)!
So I hope you find this information useful when planning your summer BBQs. I think not inviting any Lone Star ticks to the party is good advice to follow. Well, thanks for reading! Until next time,
Tattle the Tick
