The ticks were so bad last summer that Dr. Fred Robinson, a retired cardiologist, could hardly go for a walk in his yard in Midlothian without coming in to find a tick somewhere on his body.
They were a nuisance, but he now suspects they also are to blame for an unusual allergic reaction he has developed to beef.
It sounds improbable, but allergy doctors say patients such as Robinson are cropping up more and more, and research is pinning down a plausible explanation for what may be happening.
Much of that research is being done at the University of Virginia, where studies are also trying to help patients whose only remedy so far is to give up beef or other red meats.
Cases such as his seem to be becoming more common, said Dr. Scott P. Commins, an assistant professor of medicine and an expert on allergies and immunology. Commins is part of a team overseeing several tick-bite meat-allergy studies at U.Va.
Commins and his mentor, Dr. Thomas Platts-Mills, have co-authored several published papers on the topic since 2009. The latest paper, published in the May issue of The Journal of Allergy and Clinical Immunology, suggests that tick bites are a cause — and possibly the only cause — of the allergic reactions to red meat.
“We think there is something in the saliva (of ticks) that triggers some people’s immune systems to make an antibody,” Commins said.
Antibodies are substances the body makes to defend itself against potentially harmful bacteria, toxins and other harmful invaders. Allergic reactions occur when the allergic class of antibody binds to the substance it recognizes (i.e. the allergen), a process that results in the release of histamine, Commins explained. It is histamine that can cause swelling, hives and breathing problems.
Researchers believe the tick bite causes production of an antibody to a carbohydrate called alpha-gal, which also happens to be present on red meat.
“The unique thing is these people react four to six hours after they eat the food, so they don’t associate the food ingestion with the allergic reaction,” said Dr. Michael Blumberg, a Richmond allergist at Virginia Adult & Pediatric Allergy & Asthma. “I am sure we missed a lot of people … in the last 10 years. We didn’t realize this as a probable cause.”
For some people, any red meat is a trigger.
“It doesn’t really matter for patients whether its beef, or pork or lamb or buffalo or venison. And it’s hard to think of something that would cross all those different kinds of animals,” Commins said. “So it seems that it’s really just the fact that these sources of meat all come from mammals.”