A rare meat allergy has increased in prevalence over the past 10 years in the United States, in correlation with bites from the Lone Star tick. Named for the white dot on the back of the female ticks, the Lone Star tick exists all the way from the Southwestern U.S. to the East Coast, and a bite from this insect can cause people to become allergic to red meat. This condition can remain aloof to many patients, who suddenly develop allergic symptoms to red meat when they have never had an issue in the past. 

Lone Star ticks carry a sugar called alpha-gal, which people do not carry, but is found in red meat. When a Lone Star tick bites a person, it transfers alpha-gal into the bloodstream, causing the body’s immune system to react. The body develops antibodies to the sugar, so the next time the person eats red meat, the immune system reacts and fights the alpha-gal from the meat with antibodies. This can cause allergic symptoms like itching, burning, hives, vomiting, diarrhea, or even throat swelling or anaphylactic shock. Treatment for these allergic reactions includes antihistamines for mild reactions, and epinephrine for severe or life-threatening reactions. Talk to your allergy doctor if you suspect a reaction to red meat, or unusual allergic symptoms for which you cannot identify a source.

Researchers are unsure of why the sudden increase in prevalence of this allergy. Some attribute it to the hygiene hypothesis, while others suspect a new tick-based bacteria or organism, or an issue with the way humans process and handle meat. The best advice for avoiding this allergy is to wear bug spray and layers when enjoying outdoor activities in areas that have ticks, and to check for ticks after being outside.

Tam R. How One Tick Bite Can Lead to a Life-Threatening Meat Allergy. PBS. 2014. http://www.pbs.org/newshour/updates/tick-will-make-lose-appetite-red-meat/.

WebMD. Tick Bites Linked to Red Meat Allergy. WebMD. 2014. http://www.m.webmd.com/allergies/news/20140813/tick-bites-red-meat-allergy.