Summertime is for backyard cookouts, hiking along wooded trails, camping and exploring the outdoors. But it's also when ticks are most active and ready to bite.
One tick-borne disease in particular, alpha-gal syndrome, is gaining attention for its ability to cause an allergy to red meat and dairy. It's especially prevalent in a belt of states from North Carolina and Virginia all the way to Oklahoma, where the lone star tick, a primary carrier of alpha-gal, is dominant.
We caught up with Michael Reiskind, a professor of entomology at NC State University who specializes in the ecology of disease vectors such as mosquitoes and ticks, to talk about the rise in cases of alpha-gal syndrome, what causes it, how to treat it, and most importantly, how to avoid it.
How does a tick bite cause an allergy to red meat?
Alpha-gal comes from when a tick bites a person, and that tick injects its saliva while feeding. Certain ticks have saliva that includes a sugar molecule called alpha-gal that's also in non-primate mammals. That sugar molecule elicits an immune response in your body, essentially causing you to make antibodies to that sugar molecule. That's all well and good, except that the next time you eat red meat or sometimes dairy products, that sugar molecule can be in the meat or dairy. Your body then reacts to that, triggering an allergic reaction. Sometimes that allergic reaction can be quite severe. It can even cause anaphylaxis and send people to the hospital.
What is driving the rise in alpha-gal cases?
The reason we see this red meat allergy rising is that ticks are becoming more and more abundant, and so are deer, a common host animal and food source for ticks. And when people enter that tick-deer-cycle, particularly when our neighborhoods are kind of being infiltrated by deer, you get exposed to ticks that are more likely to carry alpha-gal, and we then have more and more cases. We've seen a rise in this over the last decade.
What happens in your immune system when you get bitten by a tick carrying alpha-gal?
When you get bitten by a tick carrying this alpha gal molecule, your body makes antibodies to it, and it produces a particular type of antibody called IgE. This IgE antibody is the one that tells your body to mount an allergic response. It's essentially the same antibody that is responsible for things like hay fever or if you react to a bee sting in an allergic way. And what that antibody does is signal cells in your body to release lots of histamines. These histamines call other cells to release more histamines, and they call other cells to infiltrate the area and that causes symptoms like swelling or itching.
What specifically do you become allergic to, and how do you have to change your lifestyle when this happens?
It's generally an allergic response to eating mammal meat, specifically sugar molecules in the meat. Poultry is okay: You can still eat chicken, but pork and beef and almost certainly deer are going to elicit an allergic response. In some cases, dairy products as well, although that doesn't seem as common. The change in lifestyle primarily involves avoiding those foods. There's not really any treatment one can take. With any allergic response, antihistamines like Benadryl are always a good first response. And if there are signs of a more severe response like not being able to breathe, hives all over the body or itching all over the body, I'd go to the emergency room. In worst-case scenarios, some people may need to carry an EpiPen.
What are the best ways to avoid getting alpha-gal?
The best way to avoid alpha-gal is by not getting bitten by a tick. You can avoid getting bitten by not going to places where there are ticks, but sometimes we want to go recreate in the outdoors, go for a run in a state park, camp out or go hunting. In those cases, personal protection is really the key. You should wear protective clothing. You can do things like tuck your pant legs into your socks to keep ticks from getting in. You can also wear repellents that keep ticks off. Permethrin-treated clothing can be effective, as is good old-fashioned DEET.
The final piece is to check for ticks, because once they crawl on you, they'll look for a nice place to feed and tuck in. If you can get them off of you before they bite you, then you've avoided the problem. And even if you can get them off of you relatively soon after they have tucked in to feed, that can still help avoid a lot of disease transmission. Have a close friend help you check your body for ticks when you get back from being outdoors. Areas that you want to be particularly concerned with are places that are a little bit hard for you to see, like your back, under your hairline and along the back of your head, your groin region and armpits.
How prevalent is the lone star tick in North Carolina, and are there other ticks that can transmit alpha-gal?
The lone star tick is found throughout the state, and in the Piedmont region often makes up about 90% or more of the ticks we capture in field sampling, and around 65% of the ticks that people find on themselves or their pets. That being said, we do suspect other ticks may be able to elicit the alpha-gal allergy, including the vector of Lyme disease (Ixodes scapularis). However, the timing and distribution of the allergy is strongly suggestive of the lone star tick being very important.
How common is it for alpha-gal to be found in lone star ticks?
We don't really know the carriage rate for lone star ticks, but of people who have been tested for this response, and they test it by looking for the antibodies in the blood to the alpha-gal sugar molecule, it's about 30%, which is incredibly high. But remember, these are people who have symptoms already and then doctors are sending their blood out for testing. So, 30% of those people are positive. That still suggests there are a lot of cases of alpha-gal out there and that it is a significant problem.
What kind of research are you doing to help reduce the spread of tick-borne diseases like alpha-gal?
At NC State, we have research looking at the distribution of the lone star tick, which we think is most responsible for the alpha-gal allergy, including where it is in association with trails. It's better to stay on the trail than get off the trail. We're also looking at the fine-scale association with it, including where you see larvae, nymphs and adult ticks. We have a project right now looking at the connection between deer abundance and tick abundance. All of these things can help inform people how to avoid these ticks and reduce the risk of getting a tick-borne disease like alpha-gal.
This post was originally published in College of Agriculture and Life Sciences News.
