May 28, 2013 -- A tiny tick might be to blame for a rash of red meat allergies across the United States, researchers say. And the latest study suggests grill-loving kids are just as vulnerable as their grown-up counterparts.
"Nearly 50 percent of the kids in our study ended up in the emergency department," said study author Dr. Scott Commins, an assistant professor of medicine at the University of Virginia in Charlottesville. "Age doesn't seem to really matter in terms of the severity of the reaction."
Commins and colleagues studied 51 kids who had reactions, ranging from rashes to anaphylactic shock, to mammalian meat. And like adults with the bizarre meat allergy, they all had a history of bites from Amblyomma americanum, better known as the lone star tick.
"We were surprised by how many kids were having reactions when we started looking in pediatric clinics for it," said Commins, who first linked the tick to meat allergies in 2009. He believes the bug's saliva can seep into the bite wound, somehow triggering an allergy agonizing enough to convert lifelong carnivores into wary vegetarians.
"People will eat beef, and then anywhere from three to six hours later start having a reaction, anything from hives to full-blown anaphylactic shock," he said. "And most people want to avoid having the reaction, so they try to stay away from the food that triggers it."
Most of the kids in the study developed a rash at the site of the tick bite before reacting to red meat, and all but six of them also tested positive for alpha-gal antibodies -- blood proteins that react to a sugar found in meat. But Commins said it's tough to make a definitive link between the tick and the allergy.
"We're still searching for the mechanism," he said, describing plans to test the theory in mice that were genetically altered to lack alpha-gal. "It's hard to prove."
Allergies are immune reactions to foreign substances, such as pet hair and peanuts. As antibodies attack the substance that caused the reaction, they trigger the release of histamine, a chemical that causes hives and, in severe cases, life-threatening anaphylaxis.
"If a child has an exaggerated skin response to a tick bite, I would make an appointment with an allergist to have a blood test done," said Commins, "especially if the child happens to be one who eats meat."
Other common food allergens include nuts, shellfish, milk, eggs, soy and wheat. Most food allergy sufferers are glad to discover the source of their misery, even if it means upheaval for their diets. But Commins said meat allergies can be hard for brawny barbecuers to swallow.
"Some people are totally destroyed," he said. "Others say, 'Maybe I'm better off without it.'"
But don't despair. Commins said the reaction wanes over time, and that most people are able to return to their meat-eating ways within a period of months.
"It's important to have your blood test redone because it appears that this allergic response goes away over time, which is great news for kids," he said. "Additional tick bites, however, seem to push that response back up relatively quickly. So I would really stress tick bite prevention."
The U.S. Centers for Disease Control and Prevention recommends taking the following steps to prevent tick bites:
Avoid wooded and bushy areas;
Walk in the center of trails; Use bug repellents that contain 20 percent or more Deet on the skin;
Use bug repellants that contain permethrin on clothing;
Shower as soon as possible after coming indoors;
Look for ticks on your body, especially under the arms, in and around the ears, inside the belly button, behind the knees, between the legs, around the waist and in the hair;
Check gear and pets for ticks.
Click here for more on tick bite prevention.