Tiny creatures spread disease as they find their way onto humans

[00:00:00] Host Amber Smith: Upstate Medical University and Syracuse, New York invites you to be "The Informed Patient" with the podcast that features experts from Central New York's only academic medical center. I'm your host, Amber Smith. Over the past four years, Dr. Saravanan Thangamani's lab has tested more than 26,000 ticks from Central and Upstate New York. A third of them carried at least one pathogen, most often the bacteria that causes Lyme disease. We'll hear more about tick research from Dr. Saravanan Thangamani. He's a professor of microbiology and immunology at Upstate, and the director of the SUNY Center for Vector-borne Diseases. Welcome back to "The Informed Patient," Dr. Thangamani.

[00:00:43] Saravanan Thangamani, PhD: Thank you for having me again.

[00:00:45] Host Amber Smith: Before we delve into your research, I'd like to get your prediction for what this year's tick season is liable to be like, since Central New York had a really kind of mild winter. Do ticks like mild winters?

[00:00:57] Saravanan Thangamani, PhD: Yes, a mild winter is directly proportional to the number of ticks that humans will encounter in spring and summer and the fall. As we all know that when the winter is mild, we get early spring. That means that we get out early as well, you know, and also ticks, it's the right time for the ticks to be out as well, to seek a mammalian host. And humans, or dogs, or our pets kind of venture into the wooded areas. They get bitten by a tick and they bring it home, and in turn they crawl on us and bite us as well. So it's a confluence of events that is all triggered by warm winter.

[00:01:39] Host Amber Smith: So can you remind us where ticks like to live.

[00:01:43] Saravanan Thangamani, PhD: In general, ticks tend to be found in wooded areas, tall grass or brush, edges where woods and lawn meet, in the leaf litter, under the ground cover of the plants, and around stone walls and wood piles, where small mammals like mice and squirrels tend to live in.

[00:02:01] Host Amber Smith: I know there's a lot of different species of ticks. Do they coexist with one another? Do they get along?

[00:02:08] Saravanan Thangamani, PhD: Well I wouldn't say they coexist, but actually they might be sharing the same habitat. In some of our field tick collection sites, we collect three or four different tick species, not necessarily from the same pile of wooded area, but in the whole neighborhood. We tend to see that. So they can tend to live in the same property, not necessarily coexist.

[00:02:32] Host Amber Smith: Now, which ticks are the most prevalent in Central and Upstate New York?

[00:02:36] Saravanan Thangamani, PhD: Deer ticks, of course. They are the most prevalent tick species, followed by dog tick and Lone Star tick. But I must warn that although we are more focused on the Lyme disease agent tick, which is the deer tick, two other tick species that I mentioned is also making its way to Central New York and to the Northern New York and Western New York. Ticks like Lone Star ticks, and Gulf Coast ticks are also on the emergence. Right now, they tend to cluster at the lower Hudson Valley or tri-state area. But what I'm seeing from our own data is that slowly we are starting to see these ticks in Central New York, which means that in the next few years we can see those ticks establishing population, proudly encountering humans and causing human health illness as well.

[00:03:25] Host Amber Smith: Your data showed that most of the ticks that were submitted through the Citizen Science Tick Testing program have been female. Why is that?

[00:03:34] Saravanan Thangamani, PhD: I think it is the biology of the ticks. You know, for the ticks to perpetrate in nature, they need more females because female slice thousands of eggs. The only purpose of male is to mate with the female, and females are the one that is responsible for the reproduction and to have thousands of larval ticks. So it is probably an evolutionary processes over millions of years that females are necessary to maintain the species level in this ecology. Males only serve to mate with the females, and that's it.

[00:04:05] Host Amber Smith: Well, you published a paper in Nature.Com's Scientific Reports Journal not long ago about where ticks attach to humans. Which areas do the deer ticks favor?

[00:04:17] Saravanan Thangamani, PhD: So deer ticks, generally they are found throughout the body. However, I would say they tend to prefer head, mid-section and groin areas. So those are the places where we tend to see the majority of the ticks. But our data show that deer ticks can actually, attach to human all over the body.

[00:04:36] Host Amber Smith: So how fast do they move? If I'm thinking, if you're walking through leaves, and they climb onboard your ankle, how long until they make it to your groin or to your chest?

[00:04:47] Saravanan Thangamani, PhD: They are persistent animals. They will actually crawl over you, your clothing material or under the skin all the way until it finds its perfect spot to attach and feed for longest period of time. And they are very clever. They have adapted this behavior over millions of years that they need to go and attach in a location that is safe for them, so humans don't actually easily locate and pull it off. You know, if that happens, it defeats the purpose of its life cycle, right? So they're very clever to adapt themselves for that kind of activity.

And also, people, they spray their body with the chemicals, right? Repellants or mosquito repellent that repels them. But we don't put all over our body, right? We only put our forearms or legs, whatever we expose our skin to, or around the neck. So that's why they like to kind of escape from those area because they are being repelled from that area. They're forced to move out of that area. And then they find areas where we don't actually put repellants.

[00:05:44] Host Amber Smith: So that's why they like the groin or the chest or the midsection?

[00:05:48] Saravanan Thangamani, PhD: That is one possibility, but also it is nice warm and humid environment there as well. You know, that favors attachment. And, again, is one of the least places we will try to apply tick repellants.

[00:05:59] Host Amber Smith: So does that apply to dog ticks and Lone Star ticks, too? Do they like the same areas?

[00:06:04] Saravanan Thangamani, PhD: Not necessarily. Dog ticks preferably, they like to go to the head, head and neck area. And, Lone Star ticks, they prefer thigh, groin and abdominal as well, similar to deer ticks. We are still trying to understand why dog ticks prefer the head, but that's something that we are hoping that -- you know, we have large sets of data now we are currently analyzing to see, are we still seeing the same pattern or not?

The data set that we published was from the year 2020, but now we have three years worth of data instead of one year. So we are actually reanalyzing the whole thing, three years worth of data, and then trying to see that, OK, are we still seeing the same correlation? Are we still seeing the same pattern? And we are hoping to publish this in the next year or so.

[00:06:50] Host Amber Smith: What did you find about infected versus non-infected ticks?

[00:06:54] Saravanan Thangamani, PhD: So interestingly in the deer ticks, because our dataset had enough infected ticks for us to analyze, we saw that there was a change in the bite location, if it was a Borrelia infected tick or Borrelia uninfected tick. Primarily, the infected ticks prefer to feed on the groin and midsection area of the body, over the rest of the body section. So that is something that we saw.

Again, this was from a dataset from a single year. Now we have three years worth of data. We are going to compare it. Our dataset is now more robust, and we are currently analyzing it. But the trend is there, and we are hoping to apply statistical analysis to make sure that whatever we find are indeed statistically significant.

[00:07:36] Host Amber Smith: Have you looked at where ticks prefer to attach on dogs?

[00:07:41] Saravanan Thangamani, PhD: That is a great question. I think that's something that one of our lab researchers is looking into that. We are currently teasing apart this data. We do have the data. We are now teasing apart the data.

[00:07:50] Host Amber Smith: So if you take your dog for a walk in the woods, and you come back and the dog has ticks that you may or may not see are the ticks likely to get into the carpet back at your house or get wherever they can find a spot and then hang out, waiting for a human? Or once you comb it off the dog or they fall off the dog, they're just going to die?

[00:08:10] Saravanan Thangamani, PhD: So what happens, ticks will try to first crawl on your body first before they go around the ear of the dog to kind of attach because that's where dogs can't groom easily. The rest of the body, they will groom nicely. Or under the tail. Those are the difficult parts for them to reach out, so that's where they go. Or right below, right behind the neck, actually, that's where I see ticks in our dog. That's consistently, that's where I see, because dogs can't reach there, right?

But ticks, they will first try to crawl to the legs and then slowly make its way, right, before it reaches this nice spot, if it comes back to the home and it started playing with your kid, and then somehow the kid rubs off the tick, it goes into the carpet, right? Accidentally. And then it waits for the next human to come to you, or they will start to crawl to the corner of the house and wait. Or if the dog shares the bed with you, for at least for a playful time, the ticks will drop off in the bed and then waiting for us to go and lie down and sleep the whole night. So that whole night is available for the tick to find us and eat. And that's why I tell the pets are the worst factor in this equation of diseases. Sorry, the dogs. Dogs and cats, I would say equally are the major factor in actually bringing ticks into the home and exposing humans because they have thick coat, they try to comb as much as possible. And, when we walk in the woods, dogs are the ones that they want to wander. We like to throw the stick and try to make them grab, or ball, to grab.

The moment they move away from the walking path, I think they are exposed to ticks, particularly in Central New York. I would, anytime the dogs go into the woods and come back, even if it is for like, let's say 10, 20 seconds, I would do a thorough check on the dog for the tick.

So dogs play a major role. That's why I'm telling that I kind of attribute that to human behavior as well because it's humans who actually encourage the pets to wander off and come back, and it's humans who allow the dog to sleep with us. So I attribute that anthropogenic behavior is actually a factor in putting us in risks of exposing to tick bites.

[00:10:18] Host Amber Smith: This is Upstate's "The Informed Patient" podcast. I'm your host, Amber Smith. I'm talking with Professor Saravanan Thangamani about the tick situation in Central and Upstate New York.

I'd like to ask you about the impact of climate change on the geographic expansion of tick-borne diseases in Upstate New York. We've had a series of mild winters. What is that doing overall, like long-term, to the prevalence of ticks?

[00:10:45] Saravanan Thangamani, PhD: I think three things will happen. One, the number of ticks will increase. The geographic expansion of ticks into new geographical areas where ticks have never been reported will also expand. Three, the number of infected ticks will also increase. I would attribute that to the change in climate, change in human behavior, and change in wildlife behavior that are directly as a result of climate change.

[00:11:12] Host Amber Smith: So are we seeing ticks here in Central New York that used to only be found in warmer areas?

[00:11:19] Saravanan Thangamani, PhD: I wouldn't say warmer areas because we only collect data for the state of the New York. But I can tell that ticks that are used to be presented in the tri-state area -- which is really, you know, New York City and Long Island area -- we are now starting to see them in Central New York and Upstate. And that is a trend that when we started this program in 2019, we never saw those things.

And then in 2020 we started to see those ticks appearing. And then over the years, we are getting more and more ticks from Central New York, and let's say Oswego counties, like closer to the Canadian border, and Western New York. And if you look into our nyticks.org tick map dashboard, we are seeing more ticks in Western New York compared to, I would say, 2019. So that is definitely an indication that ticks are actually emerging in new geographical areas. Ticks are increasing in greater numbers. And infected ticks are also increasing in greater numbers.

[00:12:11] Host Amber Smith: And so, logically, would we likely see more people who become ill with a tick-borne disease, Lyme disease, and there's others too, right?

[00:12:20] Saravanan Thangamani, PhD: Unfortunately, humans will encounter the ticks. But if they actually follow proper precautions, proper procedures to remove the tick as soon as they come back from an outdoor activity, they don't need to have tick-borne illnesses. So basically, they will encounter. We cannot stop that because we can't eliminate the tick population. The humans will definitely encounter more ticks in the future. However, will they succumb to the disease or not? It depends on the human behavior. It depends on do they do the tick checking? Do they apply the natural chemicals or the tick repellant products, or do they treat their outerwears with permethrin that repels the tick and kills the tick? So it depends on a combination of human behavior as well.

[00:13:02] Host Amber Smith: Where do things stand with your work on an anti-tick vaccine or a transmission blocking vaccine?

[00:13:08] Saravanan Thangamani, PhD: We kind of put that work on a pause for a while because my entire lab focused on the Citizen Science Tick Testing program. It kind of swallowed our lab, for a good reason. I think we did get a really good set of data. We help the public. We are helping the clinicians. We are helping the public policy makers as well.

But that kind of took all of our resources, I would say, into the Citizen Science program. But now we are taking a step back from the Citizen Science program and then trying to refocus on our basic science, our translational research to develop an anti-tick vaccine.

So, I'm hoping that -- you know, we have identified potential candidates. We are evaluating that in a preclinical model system, and if that is successful in a preclinical model system, we can then take it to the next level. So it is, we have switched gears on the project now.

[00:13:56] Host Amber Smith: The way you envision it though, would a tick vaccine protect humans from infection but not harm the tick?

[00:14:05] Saravanan Thangamani, PhD: No, actually. So it will prevent the ticks from feeding on us. So they will try to attach, but they will not feed on us, and they will drop off even before they have the ability to transmit a disease causing agent. And eventually the tick will die because ticks try to feed on humans only once. So when they lose the chance, they will die.

[00:14:27] Host Amber Smith: So they don't go looking for another human if things don't work out with the first one?

[00:14:31] Saravanan Thangamani, PhD: I think the biology is that they try because they have already wasted the resources in attaching, because when they actually try to get into our skin, they secrete certain salivary proteins including cement proteins. They're mostly glues. And actually that damages some of their biological properties to reattach. So it's very rarely they will go on reattach. They might probe on you. But once they stay attached for a good amount of time, let's say, half a day, they, when they drop off, they will never go and find it.

So the good thing is that ticks will drop off. The second thing is that, the ticks will drop off before it has the ability to transmit, like, Borrelia burgdorferi, the Lyme disease causing agent.

[00:15:12] Host Amber Smith: Is there a benefit to ticks? Do they have a role in nature?

[00:15:18] Saravanan Thangamani, PhD: I think they do have a role in nature. Every single organism plays a role in the ecology. And as far as the ticks are concerned, I think that they are used as food for birds. Chickens eat them. And ants also forage on ticks, as well. Fire ants, at least in Texas, I know that if you see more fire ants on your property, you will not see ticks.

In ecology, every single speeches plays a role in such a way that it helps other species to perpetuate. And definitely, ticks are a good nutritious meal for birds and ants and chicken and possums.

[00:15:54] Host Amber Smith: Well, Dr. Thangamani, thank you for making time for this interview.

[00:15:58] Saravanan Thangamani, PhD: Thank you very much. I really appreciate talking to you about this program.

[00:16:02] Host Amber Smith: My guest has been Dr. Saravanan Thangamani. He's a professor of microbiology and immunology at Upstate. "The Informed Patient" is a podcast covering health, science and medicine, brought to you by Upstate Medical University in Syracuse, New York, and produced by Jim Howe. Find our archive of previous episodes at Upstate.edu/Informed. This is your host, Amber Smith, thanking you for listening.