Tick Populations Are Expected to Surge Across the Country. But Around Charlotte, Ticks Can be Hard to Find. Why?

Davidson College Student researchers in Prof. Kevin Smith's class investigating ticks in North Carolina

Tickborne diseases are quickly becoming a public health problem in the United States. But Professor Kevin Smith and student researchers like Victoria Anyanwu (left) and Emma White will investigate why the North Carolina piedmont isn’t following the nationwide trend.

Thanks to a mild winter—and increased outdoor activity by people looking to get out of their houses during the pandemic—the upcoming summer is expected to bring a surge in the tick population.

And that means more than just close encounters with the blood-sucking bugs. The eight-legged parasites can be vectors for a number of diseases, including Lyme Disease, Rocky Mountain Spotted Fever and many others.

The Charlotte region, however, seems to be exempt from this, um, uptick. Davidson biology professor Kevin Smith and a number of student researchers published research earlier this year that showed a surprisingly small tick population in the North Carolina piedmont. Their paper ran in the Journal of Medical Entomology in January 2021. Smith’s research was partially funded by a $770,000 grant from the National Science Foundation.

With tick season peaking, Smith answered some questions and provided context on the local tick population.

Your study shows that the tick population around our part of the North Carolina piedmont is low— which runs counter to predictions. Why is that?

This is shaping up to be a bit of a mystery; ticks are becoming a pretty big problem (both as a nuisance and a public health threat) in many parts of the east, but for some reason not right around here.

For example, there’s no clear reason why our deer tick numbers are so low; we did not find a single adult deer tick in our sampling. We have plenty of deer and other hosts, and we have lots of apparently suitable habitat. Because they ride on deer (and pets and people) ticks can move around pretty well. So why aren’t they established and abundant here? I think that is a bit of a surprise.

If we can identify why that’s happening here, it might help us understand why ticks are becoming such a problem elsewhere. Is there something different about the environment here that makes it less tick-friendly? Identifying that difference may help us address tick overabundance in other regions.

Are the rates of tickborne diseases (TBD) accordingly low too?

Yes, but again, only in our sub-region. Ticks, and tickborne diseases (TBDs), are spreading and becoming more common in the eastern United States. To the north, including in North Carolina along the Virginia border, Lyme Disease is increasing. To the east, other diseases like Ehrlichiosis are on the rise as well.

Fortunately, this doesn’t mean they are a problem everywhere. In our part of North Carolina and in other parts of the east there are still places where people can go out and enjoy themselves with very little risk of encountering a tick and even less risk of being exposed to a TBD. So, people who enjoy the outdoors should be wary and mindful, but not fearful. Driving to the hiking trails is almost certainly more dangerous than going for a hike.

What are some possible explanations for the small tick population around Charlotte?

It could be so many things. It could be that we have lots of mesopredators (coyotes, foxes, bobcats) that keep rodent densities low. But we’re not unique in that way.

It could be that we have lots of possums which, interestingly, are really good at killing ticks. Despite their reputation, possums are fastidious self-groomers and kill any ticks that get on them.

It could be that our forest structure is just different enough (not enough oak trees, not the right kind of oak trees, something different about the understory communities) such that we don’t have as many small rodents, which are important hosts for the early life stages of ticks.

This is what we hope to start looking into next, answering the “why” question that follows from our study. 

Is this good news? Many of us find ticks repulsive, but it’s not good to see any major species mysteriously absent from the ecosystem.

This is a hard question. It depends on what you value in nature and biodiversity. But you don’t have to worry about ticks; they’re definitely not ebbing and are generally increasing most places.

Some people look at non-human nature and focus on the intrinsic value it holds; every species has that kind of value and has a right to exist. Even ticks and mosquitoes are biological and evolutionary works of art that have value as pieces of a huge and intricate puzzle.

But that’s not the only valid way to value nature. We know that different species have different levels of value from a human perspective, and from that perspective disease vectors such as ticks may have negative value. That is, natural areas will be seen as more valuable by most people if they lack things like ticks. But this is a slippery slope because this [thinking] is what led to mountain lions and wolves being hunted, trapped, and poisoned to extinction around here.

From my perspective we do have some valuable natural systems in this part of North Carolina, and we get to have those without having to worry about ticks and TBDs. I’m comfortable declaring that a good thing and also comfortable saying that we would lose something valuable if we suddenly had to start worrying about Lyme Disease, Ehrlichiosis, and Alpha-gal syndrome every time we went on a hike in the woods.

How can people minimize exposure to ticks and tickborne disease?

I’ll share what I tell summer research students, who spend a lot of time working outside: Vigilance is your best friend. This advice works for avoiding poison ivy, venomous snakes, bee stings, and of course, ticks.

Ticks can’t jump and ticks don’t drop down from trees. This means they can only get on you when you come in contact with whatever they’re on, usually the ground, tall grass, or shrubs. So that means avoiding tall grass. If you do walk through tall grass, check your legs for ticks. A tick’s first instinct is to climb up, so watch for that behavior. When you get back to your car, check again. When you get home, check again. When you take a shower, check again. This kind of vigilance by itself could prevent most exposures to TBDs; you can’t get a TBD unless a tick bites you, and even then, most TBDs require 12-48 hours to be transferred from the tick to you. This gives us a lot of breathing room for prevention.

If you’re worried about ticks and know that you’re likely to encounter them, then I recommend treating shoes, socks, and pants with permethrin, which is generally considered the safest and most effective chemical defense against ticks. Permethrin can actually kill ticks, but ticks will usually drop off of permethrin-treated clothing before it kills them. Even if you think that the only good tick is a dead tick, all that matters is that it’s given up on making a meal out of you.

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