Nancy, a 45 year old park ranger, developed generalized hives, dizziness, and difficulty to breathing four hours after she ate beef.  She recalled being bit by ticks frequently since she works at a national park.

90% of food allergies are from peanuts, tree nuts, fish, shellfish, wheat, soy, milk, and eggs.  An allergy to meat is extremely rare.  Food allergies occur when people with genetic predisposition develop antibodies (IgE) to specific proteins (allergens) in the food.  In general, food allergy occurs within minutes to several hours after eating the offending food.  However, the onset of severe anaphylactic reaction is always immediate.

Since 2008, more than 1500 cases of meat allergies linked to ticks have been reported.   The link between a meat allergy and a tick bite is really unexpected and fascinating.   Tick-triggered meat allergies may very well have occurred, unnoticed, for years due to unusual presentation of delayed reaction.  Tick triggered meat allergy is a food allergy, not a disease like Lyme disease or Rocky Mountain spotted fever.

An allergy to meat occurs in some people with genetic predisposition through the development of anti-alpha-gal antibodies in their body after a tick bite, especially the lone star tick.  Four to six hours after consuming the meat, the anti-alpha-gal IgE antibodies in the victim’s  blood reacts to alpha-gal in the meat (beef, lamb, pork), and then triggers the chemical mediator release and causes an unusual delayed allergic reaction.  This delayed allergic reaction, different from the conventional immediate allergic reaction, occurs because alpha-gal is most concentrated in animal fat, which takes several hours to digest.   Alpha-gal reactions vary case-by-case, sometimes with a patient experiencing a severe reaction, and other times nothing at all.

In the majority of cases so far, the tick bites have become a concern for meat-loving hikers, farmers, and pretty much anyone spending regular time outdoors in southeastern states like Virginia, Kentucky and Tennessee, where the lone star tick is commonly found.

The distribution, range, and abundance of the lone star tic have increased steadily in the past 20-30 years, probably due to concurrently increasing populations of its natural hosts, white-tailed deer and wild turkey.   Moreover, there is a trend to find new cases outside of the lone star tick area.  Therefore, lone star ticks may not be the only tick carrier.  Another type of tick, ixodes holocyclus, has been reported in other countries such as Australia, Spain, France and Sweden.

Presently, there are only a few laboratories that are capable of measuring anti-alpha-gal IgE.  In the meantime, people with a history of meat allergy and tick bite should avoid eating the meat.  Keep an Epi-pen available for patients with a history of tick-triggered meat allergy.  The good news is that the allergic reaction seems to fade after a few years in some sufferers, if they avoid additional tick bites.