A unique allergy to red meat, related to tick bites, has been found in a significant number of children in Virginia.
Red meat allergy  is especially unusual in that it is triggered by a sugar, rather than a protein as is the case with other food allergies. According to a new study published in the medical journal Pediatrics, in some areas of Virginia as many as 15 percent of children were shown to have allergy antibodies to this sugar (called alpha-gal), which can be found in beef, pork, lamb and even cow’s milk.
University of Virginia researchers suggest that saliva from the Lone Star Tick (Amblyomma americanum) is likely triggering the production of the IgE allergy antibodies to alpha-gal. This results in an immune system that is primed to react to the foods in question.
For their study, the researchers tested 51 children between the ages of 4 and 17 who had a history of delayed anaphylaxis (a characteristic of meat allergy), or who had experienced hives, with an unknown cause. They found that 45 of the patients had IgE antibodies to alpha-gal – and a majority had experienced a tick bite within the past year that had itched and persisted.
“We were surprised by how many kids were having reactions when we started looking in pediatric clinics for it,” Dr. Scott Commins, lead study author and an expert on alpha-gal allergy, told ABC News. “Nearly 50 percent of the kids in our study ended up in the emergency department.”
Back in 2009, Commins and Dr. Thomas Platts-Mills first reported on delayed-onset anaphylaxis being caused by alpha-gal. Patients, who had previously been able to eat meat without any issues, were experiencing anaphylaxis and hives three to six hours after eating beef, pork or lamb.
The pair then discovered a relationship to bites from the Lone Star Tick. People with this allergy tended to live in parts of the Southeastern United States where this tick was found, and tended to have a recent history of tick bites. However, Commins notes that this allergy has also been found in areas nowhere near the Lone Star Tick, including Australia, France, Germany and Japan.
It remains unclear why the reaction doesn’t occur immediately, as other food reactions tend to, but the answer may have to do with the fact the allergen in this case is sugar, not a protein, and may be altered during the digestive process. Commins suggests the amount of fat in the food is related to likelihood of reaction, so when it comes to cow’s milk the risk is lower, but still present.
The next step for this research is to explain why these reactions only occur after a delay, and also to determine what in the tick saliva is responsible for causing the allergy, and exactly what the mechanism is behind this phenomenon.
The better news for those who’ve suddenly had to swear off meat is that Commins says the allergy will wane in many individuals if further tick bites are successfully avoided.