“We were curious to know whether the prevalence of the allergy actually overlaid with the tick or if it was different,” says Altrich, who discussed the findings at the American College of Allergy, Asthma and Immunology’s annual scientific meeting in Anaheim, Calif. “We saw a trend in positive results to the southeastern U.S. with the tick, but interestingly we also found positive rates varying from 4 percent to 23 percent [of samples submitted for testing] outside of the tick area. We’ve actually had positives as far west as Hawaii.”
Why that is isn’t clear, says Altrich. One possibility is that those diagnosed with the allergy in places like Hawaii were actually bitten while traveling in a high-tick area like Tennessee, she says.
Another possibility is that the ticks are growing in number and their territory is spreading to adjacent states. The distribution, range and abundance of Lone Star Tick has increased steadily in the past 20 to 30 years, according to the CDC — likely concurrent with an explosion of populations of deer, the tick’s primary host.
Allergy researcher Thomas Platts-Mills of the University of Virginia has been studying alpha-gal since 2002 and was among the first to describe it in in the scientific literature. He also consults for Viracore. He says the increasing number of cases may also be explained in part by the sheer number of bites inflicted by this particular species. “This tick is very aggressive. Its larval forms will bite humans, whereas none of the other American tick larvae will do that,” he says.
Platts-Mills and his colleagues now believe that there is something in the tick saliva that causes humans to develop the alpha-gal antibodies, but he says so far no one is sure exactly what that substance is.
“Tick saliva is brilliant stuff – it has loads of substances – but if you ask me which substances are critical, I don’t know. It’s something we are working on,” Platts-Mills says.
In the meantime, ACAII President Stanley Fineman wants to spread the word so that people can avoid triggering the allergy. Fineman says too few people are aware of the allergy, or don’t make the connection between a case of hives and the meal they had much earlier in the day, and so they never get tested. “It takes four to six hours to see a reaction, so many people don’t correlate that to their meat, or hamburger or something – it’s easy to miss,” Fineman says.