A patient of ours brought this specimen into our clinic a few weeks ago, as illustrated by my crummy photography:

It was found in a yard within the city limits of Viroqua, WI. Despite the blurry lack of focus, the white mark on its back clearly identifies it as a lone start tick.

The first lone star lick I've seen, Viroqua sits just outside of the northern-most edge of their range. Lone star ticks can transmit the disease ehrlichia (anaplasma) to humans, causing symptoms similar to lyme disease. Headache and fever are hallmarks of this disease. Infection with ehrichia can be quite severe. In addition they can also transmit tularemia and Southern tick-associated rash illness (STARI). Some controversy exists as to whether or not lone star ticks can transmit lyme disease. The bacteria causing lyme has been isolated from lone star ticks on occasion in the past. The CDC currently denies that it can transmit lyme disease to humans. Though these tick-transmitted diseases are dreaded, none are as life-threatening as an allergy to alpha gal.

Galactose-alpha-1,3-galactose, also known as “alpha gal,” is a carbohydrate found in mammal meat. The lone star tick's bite has been implicated in the development of allergies to this substance, causing victims to become allergic to meat from mammalian sources: beef, lamb, pork, venison, etc. This allergic reaction can cause anaphylaxis, a very severe, potentially life-threatening reaction where a person's lips, throat, and tongue can swell, blocking his or her airway and dropping blood pressure in addition to developing hives and generalized itching. The unique thing with alpha gal allergies is that the reaction is delayed: rather than occurring immediately with exposure, it occurs 3-6 hours later. Alpha gal is also found in the chemotherapeutic drug cetuximab and in small amounts in dairy.

The good news is that reactivity to alpha gal seems to decrease over time if additional tick bites are avoided. Interestingly, people with an alpha gal allergy seem to tolerate the small amount found in dairy products, or at least do not have severe allergic reactions to them. Also, some only react to beef and not other mammalian meats. There is a non-FDA approved lab test available to check for alpha gal allergy developed by Viracor-IBT Laboratories.

Obviously, my welcome to the lone star tick is facetious, but you can't really blame the tick. I doubt that they're here on a malicious mission to sicken human beings. They're just looking to get fed and propagate their species, same as we are. But be aware of this new disease vector in the neighborhood.

Commins, SP, et al. J Allergy Clin Immunol. 2009 February; 123(2): 426–433.

©2013 by Luc Readinger, MD



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