Delayed anaphylactic shock is a new idea in the world of allergies.  Previously, it was assumed that anaphylaxis comes on within minutes of being exposed to an allergen, or not at all.

Research carried out at University of Virginia has uncovered a severe delayed allergic reaction, which they call Delayed anaphylactic shock.

It appears to be specific to a meat allergy: beef, pork or lamb.  Anaphylaxis can occur 3 to 6 hours after eating these foods for those who are allergic to it.

Symptoms can start with itching, progressing to hives on the skin’s outer and deeper layers.  Swelling, intestinal irritation come next, along with airway constriction, chaotic heart beat and a rapid drop in blood pressure.

In mild cases anaphylaxis may include only the less serious symptoms, but it is possible for this to progress to the more sever, life-threatening reactions.

"Our conventional understanding is that anaphylaxis happens within seconds or minutes of exposure. The notion that it can be delayed for several hours is a paradigm altering discovery," says senior study investigator, Thomas Platts-Mills, M.D., Ph.D., Professor of Medicine and Microbiology at UVA and head of the Division of Allergy and Clinical Immunology. 

The surprising thing about this allergy is that it involves a sugar, not a protein as with the allergies that science has so far become familiar with.

The reaction is triggered when IgE antibodies bind to galactose-α-1,3-galactose (alpha-gal), a kind of sugar.

So what causes the IgE antibodies to alpha-gal to be produced in the first place?

Researchers suspect it is connected with the bite of a ‘seed’ tick, the larval form of various species of ticks such as deer ticks, dog ticks etc.

The researcher suspect that seed tick bites can occasionally cause a meat allergy in people with type A or O blood.  Those with B or AB blood appear to be protected from developing IgE antibodies to alpha-gal sugar.

The study also found that the most common allergy testing method used by allergists, the skin prick test, does not detect a red meat allergy.

Many allergists still believe that allergies do not develop after childhood.  This study makes it clear that adults can develop a meat allergy due to larval tick bites.

When hiking in areas that may have ticks, wear clothing that protects you from tick hijacking.  If you discover a tick on your skin, remove it as soon as possible in a way that removes the head of the tick from your skin.

Clothing repellents that contain permethrin (eg Permanone) can greatly reduce, but not necessarily eliminate encounters with ticks.  Do not apply such repellents directly on your skin.

If you experience significant itching and redness around the bit, talk to your doctor about getting screened for an alpha-gal antibody.

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