A Tick Bite Can Make You Allergic to Red Meat
The culprit is a sugar in the blood of mammals, and one researcher blames leash laws that left tick-covered deer in suburban yards.
Freakonomics Radio Network · Are You Really Allergic to Penicillin? (Update) | Freakonomics RadioA bite from the lone star tick can leave someone unable to eat red meat, but most people bitten do not develop the allergy.
Allergy researcher Thomas Platts-Mills and his team found the bite can trigger an allergy to alpha-gal, a sugar molecule present in mammalian blood. People who develop what he calls alpha-gal syndrome then react to mammal meat such as beef, pork, or lamb.
Platts-Mills counts it as one of three forms of food allergy, alongside immediate reactions like peanut allergy and a condition called eosinophilic esophagitis, an inflammation of the food pipe triggered by certain foods. In his view, each has a different cause and mechanism.
His explanation starts in suburban yards, where he argues that leash laws in the early 1980s kept dogs from chasing deer away, leaving neighborhoods with herds of deer covered in ticks. He says hunters often kill deer carrying more ticks than they can count.
Questions people ask
How quickly does the reaction happen after eating meat?
Usually it is delayed, often three to six hours after eating meat. That delay is unusual, because most food allergies react within minutes, and it can make the link to a hamburger eaten hours earlier hard to spot.
Are chicken and fish still safe to eat?
Chicken, turkey, and fish do not contain alpha-gal, so they are generally still safe. People with the syndrome are usually told to avoid mammalian meat, but anyone with symptoms should work out a safe diet with an allergist.
Does the allergy ever go away?
It can fade, especially if further tick bites are avoided, but it can also persist for years. Doctors usually track it with symptoms and blood tests, so patients are advised to keep preventing bites and to recheck with an allergist rather than simply testing meat at home.