Tick-Borne Alpha-Gal Syndrome Poses Risks During Blood Transfusions

A new multi-institutional study suggests that alpha-gal syndrome (AGS), a tick-borne allergy linked to meat and animal products, may also increase the risk of allergic reactions during certain blood transfusions.

Researchers from Dartmouth Health and the Geisel School of Medicine at Dartmouth found that patients with AGS may face particular risks when receiving plasma or platelet transfusions. The condition is caused by an allergy to alpha-gal, a sugar molecule associated with mammalian products and transmitted through the bite of certain ticks, including the Lone Star tick.

Alpha-gal syndrome can cause delayed allergic reactions after exposure to mammalian meat and products such as beef, pork, lamb, dairy and gelatin. Symptoms can range from hives and stomach pain to potentially life-threatening anaphylaxis.

The researchers investigated the issue after Dartmouth Hitchcock Medical Center observed severe allergic reactions in some type O blood patients receiving platelets or plasma from type B or AB donors. They hypothesized that pre-existing antibodies to alpha-gal could contribute to these transfusion reactions.

Published on August 24 in JAMA Internal Medicine, the study analysed more than 550,000 platelet and plasma transfusions across 40 sites in five countries. At nine US sites located in areas with high rates of alpha-gal syndrome, type O patients who received B or AB units experienced significantly more allergic transfusion reactions than those who received type O units.

The researchers describe the condition as transfusion-related alpha-gal syndrome (TRAGS) and say it should be considered in hospital transfusion safety practices, particularly in regions where alpha-gal syndrome is more common.

Dartmouth Hitchcock Medical Center has already stopped giving B or AB platelets to type O patients as a precaution. Researchers hope other hospitals in areas with high tick populations will consider similar measures to reduce the risk of potentially serious transfusion-related allergic reactions.