In August 2007 Thomas A. Platts-Mills, M.D., director of the University of Virginia School of Medicine’s Department of Asthma, Allergies and Immunology, went on a hike in the mountains of Virginia and was bitten by 200 lone star tick larvae. “By November I’m in London, I eat two lamb chops, and five hours later I’m covered in hives,” he says.
Dr. Platts-Mills had accidentally stumbled onto a personal experiment that confirmed a link he’d already suspected: Lone star tick bites cause meat allergies in some people.
A decade later, a 2018 study by the National Institute of Allergy and Infectious Diseases (NIAID) confirmed immune antibodies to galactose-alpha-1,3-galactose (also known as alpha-gal) — a type of carbohydrate naturally found in all mammals, including beef, pork, lamb, goat and other red meats — in six of 70 people who were treated for recurrent, unexplained severe meat allergy. All of the people lived in areas where lone star ticks were common and had been bitten by ticks. What’s more, say experts, cases of red meat allergies in the United States have been on the rise.
Discovering the Connection Between Red Meat and Tick Bites
Dr. Platts-Mills said he started noticing an increase in meat allergies among his patients in 2006. “Allergists initially didn’t believe patients. I was one of them,” he says.
At the same time, oncologists noticed patients were having allergic reactions to a new cancer drug, cetuximab, in the same southern region, including Virginia, North Carolina, Tennessee, Arkansas, Oklahoma and Missouri. Dr. Platts-Mills and his colleagues noted that the same area is also a hot spot for another tick-borne disease, Rocky Mountain spotted fever — which led them to eventually recognize that the area was the prime habitat for the lone star tick. “We realized there was a highly significant association between lone star tick bites and meat allergies,” he says.
Together with his oncologist colleagues, Dr. Platts-Mills determined that cetuximab and lone star tick saliva both contained alpha-gal. In 2008, they published a study in the New England Journal of Medicine that found that most patients who had an allergic reaction to cetuximab also had the alpha-gal antibody — and cetuximab also contains alpha-gal. He screened more patients with meat allergies and published a 2009 study that more than 80 percent had been bitten by a tick.
What about the tick bites causes a meat allergy? “Ticks’ saliva is the cutting edge for their survival,” says Dr. Platts-Mills. It allows a tick to go unnoticed on mammals for days while they feed and breed. The tick might also pass blood that contains alpha-gal from their last meal to people, setting off an allergic reaction.
A Rise in Meat Allergies
The Centers for Disease Control and Prevention (CDC) recently released a report finding that tick-borne illnesses have tripled in the past 13 years. At the same time, some experts estimate that red meat allergies have risen from 3,500 known cases in 2016 to 5,000 known cases this year.
But red meat allergies may be much more common than we realize. “In some areas around here, 1 or 2 percent of the population [could have a red meat allergy], and it may be more than that,” says Dr. Platts-Mills. He notes that an estimated 20 percent of residents of central Virginia have the antibody to alpha-gal, and of those, maybe 10 percent, possibly more, have reactions after eating red meat.
While most food allergy symptoms happen within five to 30 minutes of eating allergenic foods like peanuts or shellfish, symptoms of a red meat allergy occur three to six hours after eating red meat, according to the American College of Allergy, Asthma and Immunology (ACAAI). That delay makes it less likely for people to connect the dots and can lead doctors to misdiagnose the cause as unexplained. “A lot of attacks might be slight itching and a hive or two, so people may not come forward even though they may be at risk. On the other hand, people who get abdominal pain are being missed altogether,” he says.
What’s causing the increase? “The general consensus is that they are being diagnosed more frequently because of increased awareness in the general public and among primary physicians as well as the spread of the tick population,” explains Dean Metcalfe, M.D., chief of the mast cell biology section in NIAID’s Laboratory of Allergic Diseases.
But Dr. Platts-Mills says an increase in deer population — and thereby lone star ticks — is key. While white-tailed deer were nearly extinct in areas of Virginia and Missouri in the 1950s, “they’ve since gone up to pre-Columbus numbers. The main increase has occurred because we have deer on lawns that are carrying ticks. When hunters shoot them, some have 500 ticks on them,” he says. These deer effectively spread ticks across wider swaths of areas, where they breed on mice.
Indeed, a 2016 paper in the journal Genome Biology and Evolution found that while in the past, the lone star tick was found almost exclusively in the Southern U.S., it has “recently experienced a remarkably rapid expansion” into the Northeastern and Midwestern states, including New York and Maine, with other newly established populations in Oklahoma, Missouri and Nebraska. Today, the lone star tick’s current range is from the Southeast through the Eastern United States.
How to Prevent and Treat Tick Bites
The best way to prevent tick bites is to avoid going off the path in heavily forested and grassy areas, according to the CDC. If you do plan on taking a nature walk where ticks might be present, a few tips to prevent tick bites:
Cover up. Wear long sleeves and tuck pants into socks to minimize exposed skin. Light-colored clothing makes it easier to spot ticks.
Use permethrin. Spray your clothes with 0.5 percent permethrin, which has been shown to be the most effective at warding off ticks; it’s good for several washes.
Spray on insect repellent. On any remaining exposed skin, use a bug spray containing DEET, picaridin, IR3535, oil of lemon eucalyptus (OLE), para-menthane-diol (PMD), or 2-undecanone (skip on babies younger than 2 months old).
Check for ticks. As soon as you get inside, check your clothing for ticks. Also check your body for ticks, especially common bite areas (armpits, ears, belly button, backs of your knees, in your hair, between your legs and around your waist).
Dry your clothes. Toss the clothes you were wearing in the drier on high heat to kill any ticks that you might have missed.
Shower. Hop in the shower and rinse off within two hours of coming inside, which has been shown to reduce the risk of tick-borne diseases.
Find a tick attached to your skin? Remove it by placing tweezers as close to your skin as possible and then pull up gently and steadily until it lets go. Avoid twisting or jerky motions, which can detach the body but leave the disease-spreading head attached to your skin. Wash the area with warm water and soap and wipe with rubbing alcohol.
Symptoms and Treatment for Tick-Borne Disease
If you have been in an area where ticks live or think you’ve bitten by a tick, watch for symptoms of tick-borne illness, including fever, chills, aches and rash within the next few weeks. Lone star tick bites also itch for more than two weeks (bites from the deer ticks that cause Lyme disease don’t itch).
Lone star ticks also carry the bacterial illnesses ehrlichiosis and southern tick-associated rash illness (STARI), which is similar to Lyme disease (although note that lone star ticks do not carry Lyme disease). If you are diagnosed with one of these tick-borne bacterial diseases, they can usually be easily treated with a round of antibiotics if caught early enough.
Meat allergy symptoms, however, may not show up until much later on — as was the case for Dr. Platts-Mills. “Patients get very upset because it isn’t consistent,” he says: Sometimes they’ll eat meat and won’t have a allergic reaction, and sometimes they will. Some people also seem more prone to developing an allergy than others, though experts say they aren’t sure why — although genetics is certainly part of it. One of the men who was there with Dr. Platts-Mills on the mountain, for example, was also bitten by hundreds of ticks but never developed a meat allergy. And two other people that were there that day didn’t get bitten at all. “The ticks are smelling something” that makes some people more tempting to feed on than others, he says.
Often, the meat allergies are mild — fast heartbeat, stomach cramps, nausea, diarrhea, hives, swelling, headaches, sneezing, a stuffy or runny nose and asthma. A few people, however, experience anaphylaxis, a life-threatening condition in which they have trouble breathing and their blood pressure drops dangerously low, according to the NIAID. If you think you have a meat allergy, check in with an allergist. For meat allergies, “skin testing is not too helpful. After taking a careful history, allergists do a blood test,” says allergist Janna M. Tuck, M.D., a spokesperson for the American College of Allergy, Asthma and Immunology (ACAAI).
Unfortunately, if you do become allergic to red meat, the only treatment is to avoid eating it. “There are treatment possibilities for other food allergies, so stay tuned regarding red meat allergy,” says Dr. Tuck.