Ticks, Mosquitoes, and Human Health
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RICK WEISS:Welcome, everyone, to this SciLine media briefing on ticks, mosquitoes and human health, an appropriate topic for this season, as things start warming up across the country. A very brief introduction to SciLine for those of you who have not joined us on one of these briefings before - SciLine is a philanthropically supported, free service for reporters, supported by a handful of philanthropies with one goal in mind, which is to get more scientific information, evidence-based facts, into news stories. And we do that through a variety of ways, including a real-time matching service through which reporters can get in touch with us, and we help you find experts who can be - provide context and information for the stories you're working on. We do it through fact sheets that are posted on our website on a variety of topics related to science that you may be working on stories about. We do it through boot camps, where we train reporters over the course of 2 1/2 days or so on various topics, all expenses paid, to get you up to speed so you can do deeper reporting on these topics. And we do media briefings like these about every four to six weeks - again, on the record, for your use, to meet these experts, to hear what they have to say, to ask questions and to know who they are so you can reach out to them again in the future.
Today, we have a spectacular panel of folks to present information on this topic. And I'm going to only briefly tell you who they are because their full bios are available on the sciline.org website, if you go to sciline.org/briefings. But the order of events here will be first, we're going to hear from Dr. Ben Beard. He's the deputy director of the Division of Vector-Borne Diseases at the Centers for Disease Control and Prevention, or CDC. He's also the former associate director for climate change at CDC's National Center for Emerging and Zoonotic Infectious Diseases, so may be able to handle some questions about how climate change is affecting some of the trends he'll be talking about. He will give an introductory presentation talking about some of what's going on, trend-wise, with vector-borne diseases right now. He's also going to provide a particular focus on ticks and tick-borne diseases and introduce us to the newest tick in town in North America, the Asian longhorned tick, and talk a little bit about CDC strategy for these diseases.
Second, Dr. Lyric Bartholomay, who's a professor in the Department of Pathobiological Sciences at the University of Wisconsin, Madison. She's also the director of the CDC-funded upper Midwestern Center of Excellence for Vector-borne Disease, and is involved in a project where she's teaching mosquito biology to elementary school students. So she will be sticking to two-syllable words for the most part today, which is great for all of us, I think.
Finally, I will introduce here Dr. Maria Elena Bottazzi. She's the associate dean at the National School of Tropical Medicine at Baylor College of Medicine and a professor of pediatrics and co-director of the Texas Children's Hospital Center for Vaccine Development. And she'll be looking, in particular, at the clinical medical aspects of vector-borne diseases, with some emphasis on vaccine development and some of the challenges of developing vaccines for these issues. I didn't mention that Lyric will be especially focusing on mosquitoes, since Ben will be focusing a lot on ticks. With those brief introductions, I'll just turn it over to you, Dr. Beard. And we'll start things off.
BEN BEARD: Thank you, Rick, and thanks Josh as well. And it's a great opportunity for me to be with all of you here today. So I welcome you. And I'd like to begin just by saying a little bit about the state of vector-borne diseases in the United States and particularly about tick-borne diseases. But you may not be aware of this, but between 2004 and 2017, there were more than 700,000 cases of vector-borne diseases that were reported in the United States. This number of reported cases of disease from mosquitoes, ticks and fleas - from their bites - has more than tripled over this period of time. And actually, tick-borne diseases accounted for over 75% of all the recorded, reported vector-borne disease cases that occurred. Mosquito-borne disease epidemics are happening more frequently. And we've certainly seen that, you know, in the last year with Zika and chikungunya. And I think Lyric will talk more about that. And then, finally, I want to emphasize that these are reported cases. The actual number of actual disease cases is somewhere between 10 and 70-fold greater than this. And I just want to mention that because the burden of these diseases is much greater than the actual number of cases that are reported through the public health system here in the United States. Next slide.
This slide really shows what we've seen in 2017. And in 2017, there was a record number of cases of tick-borne diseases that were reported to CDC. And as you can see, if you just look, compare 2016 to 2017, you can see that all of these disease cases were up. Lyme disease cases, now there are over 42,000 cases that were reported. And - and so forth and so on, as you can see with the other diseases, anaplasma and ehrlichiosis, spotted fever, rickettsiosis, babesiosis, tularemia, Powassan virus as well. They were all up in 2017, the highest numbers that we've ever seen. Next slide. This is a graph that really shows what we've seen in terms of the trends from 2001 through 2017. And it basically is just showing the annual increase in reported cases. The turquoise bars are Lyme disease reported cases, and those, of course, account for the largest number of cases of tick-borne diseases. But we've also seen increases in all of the other tick-borne diseases as well. The yellow bars that you see for babesiosis, that only began in 2011, that's because it just became nationally notifiable then. Cases occurred prior to that, but they weren't reported to us at CDC. Next slide.
I wanted to show this slide. It's a little bit complicated. But - but what you'll really see here is that from 1960 through 2000 about, we have about one new tick-borne disease that was discovered per decade during that period of time. But then, when we got to 2000 or a little bit before, you know, since that time, we've seen actually eight or nine different tick-borne diseases that have been discovered or reported for the first time here in the United States. You can see these beginning in 2000 - in the year 2004, I guess, with Rickettsia parkeri, Rickettsia 364D. Some people call it Rickettsia philipii, Ehrlichia muris, Borrelia miyamotoi, Borrelia mayonii, Heartland virus. And there's actually another one that's not on this list called Bourbon virus, and it probably should be on this list. But we still lack a little more data to actually prove that it's carried by ticks. But we're pretty certain of that. And it begs the question, why are we seeing these diseases emerge? Why are we seeing more species of tick-borne disease agents as well? And part of that is because we've seen changing land-use patterns, resurgence of deer populations. We have people who are building suburban areas into these places where there are more and more ticks. And what happens is more people are exposed to more ticks and more bites. And so there's a greater risk for being exposed to a tick-borne pathogen. Next slide.
I also want to mention a new tick as well, as Rick alluded to this. And this tick was actually discovered in New Jersey in 2017. And it's now been reported from 11 states and 64 counties or county equivalents. This number, of course, is growing by the week as this - as it's being found in more areas. This tick has been found on numerous animals, including wildlife, livestock, pets and humans. It's originally from Korea, from northern China, from that area of Asia - Japan. And it's a very important disease vector there of a number of different animal and human pathogens. And it has great potential for spread throughout the U.S. The good news here is even though it's been found and we're working with USDA to track this closely, it's - none of these ticks here in the U.S. have been found effective with any pathogens here to date.
And finally, I want to use the last moment just to talk a little bit about what CDC is doing to address the concerns with tick-borne diseases. We're conducting research to improve diagnostics, to get better surveillance data, to be able to track these trends, to create better prevention and control tools. We're also funding state-based vector-borne disease activities through our epidemiology and laboratory capacity, a cooperative agreement. This is an agreement we have with state health departments largely to support them. We have established five regional vector-borne disease centers of excellence. And I think Dr. Bartholomay will talk about that in a few minutes. We've established a national surveillance system now for reporting and mapping ticks and the pathogens that they carry. And then finally, we've led efforts involving six different federal departments to develop a national strategy to address these concerns with vector-borne diseases. So I'll stop with that, other than just to show this last slide. And it has places you can go for more information. And it's got all of the CDC URLs, where members of the media can get additional information that they need. Thank you.
RICK WEISS: Thanks Dr. Beard. And by the way, for viewers, all these slides will be visible on our website after the briefing, as will, within a day or so, a full video and transcript so you can refer back to it. We'll turn now to Dr. Bartholomay, who I think you'll have to unmute there. And happy to hear what you have to say. Thanks.
LYRIC BARTHOLOMAY: Certainly. Good afternoon. Josh is bringing up my slides here. So as Ben alluded to in his presentation, we continue to struggle with mosquito-borne diseases locally and globally. So let's move to the next slide so we can see some of those key players. Here you can see an array of five different species of mosquito. These are all female mosquitoes. It's the female mosquitoes that take blood and transmit pathogens. And these are some of the - globally, some of the real key players that transmit important pathogens that are listed here and cause diseases that are listed here, like dengue fever and malaria. Locally, we have a mosquito called Aedes triseriatus that transmits a pathogen called La Crosse virus - causes encephalitis. And so there's a real spectrum here and - a spectrum of diseases, spectrum of different kinds of mosquitoes. And these things continue to be a real issue because our world is so interconnected.
Pathogens that are established in other countries and other places can really readily leap over oceans and establish locally. And witness just recently, for example, as Dr. Beard mentioned, the introduction of Zika virus into the United States and, almost 20 years ago now, the introduction of West Nile to the U.S. So the spectrum of mosquito-borne diseases continues to include deadly things like malaria, which takes the lives of some half a million people annually, and also things like elephantiasis, which causes a really debilitating disease but doesn't kill people. It does impact our life potential and impacts the economies of communities. And then we have diseases like dengue and Zika that have been in the news more recently and, I think, that people are perhaps even more aware of. So I've listed some of these things here. And at a glance, this shows you that some of these are better at transmitting pathogens than others, and it may sort of incite some fear because these are really significant illnesses. But, really, these are - for perspective purposes, these are just 5 out of some 3,500 different species of mosquito. And so there are a lot of mosquitoes out there that don't feed on humans and don't transmit any pathogens. And so - so while deadly, I think that that perspective is really important to have. So let's go on to the next slide.
So we've looked at what's still there. And then, thinking about what's new, some of the things that are impacting mosquito-borne disease locally and globally include things like human-induced changes - people moving into - increasingly into urbanized areas, easy exchange of people and animal and goods across oceans. In 24 hours, you can be across the globe - right? - and potentially bring something like Zika virus in and out with you. Of course, we have to think about climate change and its impacts on mosquito-borne diseases. Climate change absolutely impacts habitat availability and makes it possible for mosquitoes to move into places that they weren't before. And we have these increasingly frequent catastrophic weather events - right? - where flooding events, for example, could provide all-new habitat for a mosquito.
On the other hand, they could wash all the mosquitoes away. And so we have to think about how vector populations or mosquito populations would be impacted by those things. We also have invasive species. We have insecticide resistance, so the mosquitoes are resistant to the insecticides we can use against them. We have emerging and reemerging pathogens, a shifting landscape of investment in public health and research innovations and then scientific landscape of discovery and innovation. And I've put in here asterices (ph) to point out some particular points - so climate change, emerging pathogens and the landscape of scientific discovery and innovation - because these are places where there actually really is some new things going on. This list could've been a list that was put up by scientists even 20 years ago, and many of the things would resonate the same way. But now we're dealing with a whole new series of environmental challenges with pathogens we have never seen before and - with the pace of scientific discovery that's revealing all kinds of new things just daily. So we can move to the next line.
So what can we do about it? So I realize that these things are scary indeed, but we have a lot of ways, with knowledge, to empower ourselves, to protect ourselves from mosquito-borne diseases. On a personal basis, we can do things like wear a repellent and see our travel physicians when we go places to make sure we have the right vaccines or drugs to protect ourselves from mosquito-borne disease. We can do things in our own homes, like reduce the amount of breeding mosquitoes that we have by cleaning our gutters. We can put screens on our homes. We can treat our yards, potentially, for mosquitoes. At a community level, we invest, in a big way, in our center of excellence in trying to understand what mosquitoes are out there and how we teach the public about these things. And at a community level, too, some places have a tax-based ability to control mosquitoes, using some of the chemical and biological insecticides that we know work best to control larvae and adult mosquitoes. And again, as I mentioned, I think it's a - it's an exciting time to think about all the discovery and innovation potential that the research community brings, that the - that industry brings in terms of developing new chemicals to control mosquitoes and developing these new and exciting population-based controls to suppress mosquito populations and prevent them from transmitting pathogens. So although the risk is very real and potentially really distressing, we do have a lot of things at hand to intervene.
RICK WEISS: Great. Thank you very much. And we will move last, before the Q&A, to Dr. Maria Elena Bottazzi from Baylor.
MARIA ELENA BOTTAZZI:Thank you very much for the opportunity. So my expertise actually complements very well from the prior two experts. In fact, we've focused our studies and research in evaluating global health technologies, including, of course, vaccines and diagnostics. And I just want to point out that, certainly, as you know, we're really advancing very nicely with very novel technologies, including, for instance, even doing geographic information system mapping technology, having better tools for diagnostics and our group, of course, which is divided between the Baylor National School of Tropical Medicine, who really focuses on doing field work alongside with field epidemiologists to really look at the impact of these diseases, especially in the area of the Third Coast. So I'm going to give you a few examples, certainly, off of Texas - because that's where I am based - while at the same time, understanding, certainly, the problematic of these diseases in our region and how we can better detect them and study them. Then it's utilizing technology, such as vaccines, to see if we could tackle and certainly assist in preventing and sometimes treating, certainly, these diseases.
So just to give you a couple of examples - so at our National School of Tropical Medicine and with faculty members, such as Dr. Kristy Murray and Dr. Job Lopez, we certainly have seen the prevalence of some of the diseases - tick-borne, as well as mosquito-borne that you heard earlier. I just want to raise the fact that there are other vector-borne diseases that are not necessarily mosquito nor ticks. And I give you as an example Chagas disease, which is transmitted by another vector called kissing bugs. And so we clearly learning about, you know, the dynamics of transmission. And certainly, the way that we can detect them has really helped us to really understand better how to then find solutions. So what exactly do we have to do, therefore? So if the intention is to prevent transmission, maybe reduce the burden of the disease by using vaccines - which could be, of course, preventive vaccines or even therapeutic or immunomodulating type of immune therapies - it is crucial that we really focus on not only evaluating current technologies, but also developing what we so call the new vaccines or vaccines for these neglected tropical diseases. So unfortunately, there are major hurdles, right? You know, and here in the United States, we don't really have an efficient ecosystem or a real road map to really support from the beginning of the discovery all the way to the end of, how do you develop complex, scientific, technical, logistical and operational, even financial, hurdles for vaccines in this space of the neglected vector and mosquito-borne diseases?
So for example, we don't really have ways to show, maybe, the business case, which is the profitability or the financial realization - right? - of these vaccines because, clearly, they are going to be targeted to populations in need, most likely living in underserved areas. Most of them are poor populations, even within our country. So we clearly have to find ways where the ecosystem of developing a biologic certainly could be adapted for this group of diseases. And you can see it. It's evidence. Like, even if you look, currently, in the United States, there's only one approved vaccines again the - against a vector-borne disease, which is yellow fever vaccine. Now, why is that, right? First, big pharmaceutical companies certainly are driven by high competitive, high-risk, high-reward market drivers, right? So they clearly are currently divesting from investing into early research and development programs and certainly prefer to wait for technology to be quite advanced, almost to the point where it has almost no risk to be able to jump in. Second, we have, certainly, big players, you know, big foundations, like the Bill and Melinda Gates Foundation, that unfortunately - they don't directly - lately have been focusing on developing these types of vaccines or interventions. We are very honored and privileged that we have federal institutions and U.S. agencies, such as the NIH, as well as Department of Defense. They do an excellent job of funding basic and hypothesis-driven research, some early clinical trials. But clearly, what we call the valleys of death, which are the developing gaps - right? - the cost of manufacturing, the cost of doing quality control, the cost of doing very regulated studies that we - clearly are needed to eventually go into what we call in the last mile towards licensure - there's a huge gap.
So the trend right now is to use big coalitions. So I'm going to use the example of the Coalition for Epidemic Preparedness Innovations, which - they buck it. They pull funding from private agencies, government agencies, Gates Foundation, and they focus their funding and their efforts, traditionally, to some of these diseases - mostly for pandemic potential. They, of course, have in their portfolio some vaccines under development for chikungunya and even river - Rift Valley fever. But clearly, most of the investments really exclude this cohort of what we call neglected or diseases of poverty, right? So major challenges, again - you know, just to summarize - is the development cost needs are clearly a huge challenge. It costs a lot of money to develop biologicals, of course, and vaccines are amongst the most costly. The profitability models are broken because we can't really quantify that it's going to be a clear return monetary investment. And certainly, the high risk, the long timeline that you need, clearly reduce the interest of investment. So what's the response, right? You know, we - call to action. So as an example, of course, I'm going to also share that, you know, our Center for Vaccine Development here at Texas Children's are trying to do this by using a model called the product development partnership model, which clearly uses - leverages the expertise of multiple partners - private, public, in the nonprofit, ideally in the for-profit sector, even though we primarily work in the space of nonprofit - to really bring the discoveries from the early stages to the point where we can test them in the clinic.
So in our portfolio, we have, for example, two parasitic worms that are in phase two clinical trials. We have even a prototype source antigen that has already even been produced and then stockpiled in a clinical repository. We're working on prototypes, vaccines. And the optimism here is that at least there are some positive efforts underway. So I'm going to use the examples of the fact that big organizations, such as the World Health Organization, together with the National Institutes of Health and big agencies such as Gates Foundation, they have these big advisory committees that now are really trying to do two things. Look for innovation in the financial sector to see if we could find a better model to support the transition of these activities because they are costly; at the same time, looking for ways of reducing the risk with more intelligent clinical trial designs, for example. But also doing a paradigm shift on how we can quantify better this concept of what are the returns on investment. And the return of investment should not only base itself on monetary returns, per se, but utilize the public health benefit, the non-health benefits, the equity and the fairness, so that we could develop accessible, affordable and certainly reachable to certainly the population in the United States, but at the same time, it also can reach the Western world, you know, the more underserved countries.
And lastly, I'm going to just finish up with, why is it important that we're doing this media with you all today? And it's because we need help. We need help in advocating for these diseases. We need help with the right information to be out there. We need not only health officials to be better trained - and certainly Dr. Bartholomay is doing a great job trying to bring even the school-aged children to really get interested in this topic. But it's with groups like you that could help us really engage with that community, share the science, share and communicate with the appropriate stakeholders. So I hope that this is informative, and I send it back to Rick.
RICK WEISS: Great. Thank you so much, Dr. Bottazzi. We are ready now for a Q&A from journalists on the line. A reminder here that you should go to the Q&A box on your screens, and you can type in your questions there and direct them to a particular panelist if you want to or just leave it open. And we'll start off right away with the question from Nick Gerbis at KJZZ in Arizona. This is for Dr. Beard. Are the increases in reported cases of vector-borne disease that you mentioned, is that an actual increase on a population-based basis, or is it simply an increase in cases in line with the growth of the population, the human population? You're on mute, I think. Right.
BEN BEARD:Sorry about that. Yeah. We report diseases both in terms of reported cases and in the incidence. In the incidence, of course, it's a population-based calculation; it's numbers of cases per 100,000. And we've got it broken down both ways. I usually show my data in terms of numbers of reported cases because incidence is a little bit more difficult for people to understand. But we also see an increase in incidence as well. So I think the answer to that is yes, both as reported cases and disease incidence.
RICK WEISS: Got it. Thank you. A question here from Sara Peach at Yale Climate Connections, again, for Dr. Beard. Do you think that climate change is playing a role in the growth of tick-borne disease cases, or do you think the role of changing land use and burgeoning deer populations, for example, coming in contact with people is really the more important factor? Can you give relative strength to those two trends?
BEN BEARD:Yeah. That's a very good question. And in my mind, I think of the factors that - I use the word drive - the numbers of the types of factors that are driving this increase in tick-borne diseases, you know, it's complicated. And I called out changing land-use patterns, which we've definitely seen. We've definitely seen an increase in deer populations. We've seen this increase in suburban growth. And all of those things are true. How does climate change fit into that? Well, there's some things that we've observed directly and things that we've modeled. But for one thing, we've seen ticks expand their distribution in northern distribute - in a northern pattern. And it's actually distributed - it's actually increased in all directions. But temperature kind of defines the northernmost boundaries of where a species can exist. And so we're seeing ticks now in places where we've never seen them before. And so we have the ticks that Lyme disease and Powassan virus and other pathogens like that expanding all the way up into Canada. We've also seen a huge increase in Lyme disease cases up through Maine, up the - up through New York, all the way across, you know, Wisconsin and - where Lyric is - and in Minnesota.
And so I like to think of it in terms of attribution, which is what amount of the increase can - is attributed to climate change, and what amount is attributed to all these other factors that are going on at the same time? And that's a very difficult answer for us to ascertain because the other factors are driving it in all directions, and climate change is probably permitting it to be driven northward and in higher latitudes as well. We do know that ticks survive - you know, as the winter temperatures are increasing, ticks are able to survive at higher latitudes. We also notice that at warmer temperatures ticks produce more offspring, and they increase more quickly. And so we've seen an impact on seasonality of Lyme disease cases. We're seeing cases earlier in the year now than we used to see them. So all of those things are going on, and it's difficult to quantitate or quantify what you can attribute to climate change versus what you can attribute to all these other factors that are going on at the same time. Does that make - I'm sorry; that's a very long answer, but I hope that sort of unpacks that a little bit.
RICK WEISS: Not a number but certainly a contributor, it sounds like. Dr. Bartholomay, is there anything you want to add there with regard to mosquitoes and how they are responding to some of the same shifts that are climate-related, at least?
LYRIC BARTHOLOMAY:Right. So as Dr. Beard mentioned, it's really the temperature at the northern range of a vector that dictates how far it can go. And some examples of the kind of work we're doing right now may sort of speak to your question, Rick, and this also relates to invasive species. So right now we're all really keenly interested in what's going to happen with this invasive species called Aedes albopictus, the Asian tiger mosquito. This mosquito is an extreme invader. It's got this capacity to go into all kinds of places. It moves with tires and other containers and lucky bamboo and other things and, once established, is really quite a miserable species to be around. It's a daytime feeder, and the bite is really obnoxiously painful. And they're just really pestiferous but also have this potential to transmit pathogens, a number of different kinds of pathogens. And so the centers of excellence across the United States that the CDC has established are looking at where this mosquito can go. And we've seen it actually all the way into Wisconsin now. But we're looking at the impacts of things like our extremely cold winter then on the possibility for that mosquito to actually stay established. And so although there may be this range expansion, there's also potentially contraction with warm temperatures and then cold temperatures. And so it's a complicated system. But without a doubt, as temperatures increase and, like, the USDA growing zones, for example, shift further and further, that's one of those indicators that tells you kind of where there's available habitat for some of the species that we're keeping a close eye on.
RICK WEISS: Great. Question for Dr. Bottazzi. You mentioned the arrival of Chagas disease in the United States. That's a disease I think a lot of people in this country haven't heard of until recently, if at all. Can you say something more about whether that poses an imminent threat of a whole new disease for us to think about up here? And might the possibility that a developed country like the United States would suddenly become prone to that disease help, in a way, to draw attention to the need for a vaccine or drug development for a disease that might otherwise have continued to be relatively ignored in the developing world?
MARIA ELENA BOTTAZZI: Yes. Thank you. So - very good question. So first of all, I have to maybe clarify that we actually have in - especially in Texas and even in some other states, we actually have the kissing bugs. So the vectors are here and have been here for quite a while. And in fact, we have done some studies in Texas, especially in the counties very close to the Mexican border, and we do find that these kissing bugs, around 50% of them, especially those collected in the very domestic areas around the residences that are infected. So we do have a local transmission. In fact, you know, we have some studies that have shown that 8% of the canines are positive. We also have a lot of reservoir animals - sylvatic animals like raccoons, opossums, wood rats that clearly have served as mammalian reservoir. Indeed, you could certainly find that modes of transmission are not only directly - only by the kissing bug itself; you know, you can also transmit it by blood transfusion or even congenital transmission, and we have seen some cases already there. So I think it is - it's already a - it's a problem that we already have it here. So we really have to raise the awareness.
And we are doing both things. We are actually trying to train better the health professionals to certainly learn to identify and potentially diagnose earlier, cardiologists and physicians to know how to improve the clinical management. I think even very recently the U.S. FDA have registered the benznidazole here in the United States. It's for limited use. It's for the pediatric use, I think, at this point. But at least we now know we have access to treatment, especially for the pediatric population. And we already have a prototype vaccine development program that we currently are already in the stages of technology, transferring the prototype technology to manufacturing. We're actually working with the Walter Reed Institute for Research (ph) in the D.C. area. It's - we're very aligned with also diseases that are of military importance, for example, because we know that certainly our troops when - also are deployed or even working in their bases, you know, can be exposed. So we're already working on it. And I think that we really need to change that perspective that we don't - it is already a problem that we have, certainly here in Texas.
RICK WEISS: Thank you. Question next from Jennifer Lu at the La Crosse Tribune there in Wisconsin. And this is for you, in your home state, Dr. Bartholomay. We've had major flooding in Wisconsin, she notes, in the fall and in the spring across a large swath of the Midwest. How does flooding by season affect tick populations and tick-borne disease? I think mosquitoes would be affected as well. And what is the outlook for this year coming off of this extremely wet spring?
LYRIC BARTHOLOMAY:Yeah, it has been extreme (laughter) in Wisconsin and across the Midwest, really, for the last couple of years. Last fall in the Madison area, really late in the season, we had some serious flooding events. And those flooding events precipitated a really extreme outbreak of pest mosquitoes. So it was late in August, and we were all dealing with just intolerable numbers of mosquitoes when we were trying to be outdoors recreating. We ran some surveillance in the city during August and all through the summer, actually. And in the beginning of the month, we were seeing maybe 10 or 20 mosquitoes in our traps. By two weeks post-flood, we were getting 10,000-plus in our traps. So the traps were almost heavy, they were so full of mosquitoes.
RICK WEISS: (Laughter) It takes a lot of mosquitoes to get heavy.
LYRIC BARTHOLOMAY:Lot of biomass, absolutely. And so what that tells you is that the floodwaters were getting into places where there had been sort of a repository of mosquito eggs out in the environment. So mosquito eggs, depending on the species, can live for years and years before a flooding event occurs. So those mosquitoes had been out. They laid their eggs. And then these floods came along and hydrated those eggs and submerged the eggs. And the larvae hatched, and the mosquitoes grew, and we had this massive population of mosquitoes. Then all of those mosquitoes fed on all of us. We heard a lot of testimonials (laughter) to that extent. And then they were out laying eggs again, right? And so it's certainly possible that that has set us up this year for a large number of mosquito eggs out in the environment that, again, are being submerged by these flooding events that we're experiencing. The other side of that, as I sort of alluded to in my slide set, is that flooding can have very different potential outcomes on a - mosquitoes that are in the environment. So one possibility is that the mosquitoes get submerged as eggs, and then you get an increase in the overall population. Another possibility is that mosquitoes get submerged as eggs, the water keeps flowing really strongly and heavily, and all the larvae are washed away. And so, in fact, you don't see a huge increase.
The other possibility is that the floodwaters then recede and leave these puddles of water that stagnate, and then you have another additional sort of habitat for mosquitoes to lay eggs. And so then layered on top of all of that, Jennifer, is the additional complication that, in Wisconsin in particular, we're still sort of waiting for summer. So it's not been particularly warm. So the mosquitoes, as cold-blooded animals, are up against all of those different environmental possibilities and challenges. And so it does make it difficult to predict. I know that there are people who are locally saying the mosquitoes are awful. So up north in Wisconsin, we're seeing a lot of those spring mosquitoes that come out when the snow melts. And so there's just intolerable numbers of those mosquitoes out. But some of our typical summer species will just start to come out now as it's getting warmer and warmer. And then I would invite - if you're up for it - Dr. Beard (laughter) to talk about the impact of flooding on ticks.
BEN BEARD:I was afraid that you might do that. The - to be honest with you, I have never actually - I don't recall any articles I've read on the impact of flooding on ticks. And maybe that's because the tick-borne disease problems have been more in the Northeast and Upper Midwest, the - where the bulk of reported cases are. And then the flooding that we get involved with really, or - from an emergency point of view, has - is typically hurricanes and things like that in the coastal - Gulf coastal region. So I - but in terms of where you are, I've just never read anything - or no one's ever brought that to our attention - such as, it's been a really rainy year, and we're seeing a lot of ticks. Or, it's been a really dry year, and we're seeing a lot of ticks. It just seems to me that the problems where ticks occur are pretty constant from year to year. If you live in an area where Lyme disease is common, every year is a bad year. And the weather models that have been done, the severe storms that have occurred just haven't had a big impact that we've noticed on - at least on reported numbers of cases. So I think that's pretty much all I can say about that.
RICK WEISS: Well, maybe as a...
LYRIC BARTHOLOMAY:That's where I was at too (laughter). I guess the other thing to keep in mind when we're thinking about Lyme and the ticks that are associated with Lyme disease is that they're really dependent on all these other forest animals. And so to the extent that flooding disrupts mice and deer, then there could be an impact on Lyme potentially. But, you know, a lot of times, the places where we're - where we see Lyme disease are places that are these beautiful, pristine deciduous forests. And there's plenty of forest land where all those animals and ticks can exist that are far enough away from watersheds that the ticks - I like to bet on the ticks. I think they're going to be just fine (laughter).
RICK WEISS: (Laughter) So we actually have a related question to this from Mary Landers at the Savannah Morning News who's wondering - you know, she says she mostly thinks of Lyme disease as a disease of the Northeast. And is there a southern spread of concern to her readers in Georgia of tick-borne disease? And is that margin moving southward, while some of these other diseases are moving up? Is the range of tick-borne disease extending in the South, or is it already there? Maybe Dr. Beard.
BEN BEARD:Yeah, thanks for that question. We - tick-borne diseases have been reported in all states in the United States. So people can get them as travel-related illnesses. So it is certainly - they can bring them back on their pets. Pets can have Lyme disease. Pets travel as well. So, I mean, for that reason, it's really important for health care providers all over the country and for the people who live there to know about the risk for tick-borne diseases. And I would also say, to more directly answer the question, that tick-borne diseases are also a problem throughout the South. Lyme disease historically has been in the Northeast and Upper Midwest. We also see it on the West Coast. We don't see as many cases out there, but certainly tick-borne diseases are acquired there. They're acquired everywhere. And we have seen Lyme disease cases expand southward. And so that's clearly not - probably not driven by climate change in the way that we typically think about it. But we have seen Lyme disease, the numbers of cases, expand southward.
And one of the difference, though, is that the ticks that carry Lyme disease in the South are different behaviorally from the ones in the Northeast and Upper Midwest. And there've been some really nice studies that have looked at tick feeding behavior and shown that even though you can find Lyme disease in the South, the risk is a lot lower than it is in the Northeast and Upper Midwest - lower, but not zero. And so you can get Lyme disease anywhere, almost. And you certainly can get other tick-borne diseases besides Lyme disease in these places. And so people in Georgia need to be very aware of the risk of being bitten by a tick, protecting them, using repellents, light-colored clothing, doing tick checks and showering and all those things that we tell people in other parts of the country because there are a lot of important tick-borne diseases in the South. Lyme disease is not as big a problem, but it's there as well.
RICK WEISS: Interesting. A question I think maybe for Dr. Bottazzi - this is from Catherine Roberts, health reporter at Consumer Reports. Is there any evidence that shows whether conventional insect repellents and personal protective measures are effective against kissing bugs? Does DEET, for example, repel them?
MARIA ELENA BOTTAZZI: Good question. Well, I don't believe so, mostly because they're not like, of course, the mosquitoes or certainly some of the ticks. These are quite big, cockroach-like bugs. So they're quite big. The other thing is that they tend to approach the host and that transmission is really not through even the biting of the vector. It's actually the physical - unfortunately, I have to say that while they're feeding, they're actually defecating. And the parasite actually comes together with the - you know, with the feces. So it's really not something that certainly a repellent or, you know, one of those insecticides could possibly prevent. Now, that said, you know, certainly, we are actually working on understanding a little bit better of how can we also destroy the stages of the parasite that actually survive within these vectors - maybe even, for instance, looking at their intestinal, their salivas.
Like, we also have seen that there are studies in mosquitoes and even in ticks to look at, you know, the inherent pathogenesis of how they survive within these vectors to see if we could develop, for instance, even new drugs or even new vaccines that actually can act as transmission-blocking type of interventions. So one interesting project that we have is developing a leishmania vaccine, which is really a molecule which is a salivary gland molecule within the sand fly that, ideally, is that when it bites the host, it would certainly get the blood meal. But within the blood meal there is already an immune cell that can actually - or an immune profile that can prevent there - for the survival of the leishmania within the sand fly, for example. So we're also looking at those kinds of interventions; that we have to be innovative and tackle them both inside the house but also looking at how we can maybe disrupt the cycle of maintaining these parasites within these vectors.
RICK WEISS: Here's a question that I think any of you might want to tackle. It's a general question that actually a number of reporters have submitted in one version or another. But this is from Pat St. Claire at WABE Radio in Atlanta. Just what are the best things that people can do? What are the things they should know to avoid exposure to these diseases? Maybe each of you can just mention a few super practical tips so people know how to lower the odds of ending up with one of these diseases. Dr. Beard, do you want to start?
BEN BEARD:Yeah, I can start, and then the others can certainly add to that. I would say, you know, first and foremost, well, with mosquitoes, to wear repellent and wear them according to the EPA label. If you go to the label on the repellent, it'll tell you, you know, exactly what it's labeled for use. And so repellents are great for avoiding mosquito bites. For ticks, I kind of already mentioned that a little bit. But what we encourage people is, when you're outdoors - in outdoors in areas where you can be exposed to ticks, which can be anything from backyard to the green spaces around you neighborhood, playgrounds to wooded areas, first and foremost, to wear repellents. It's helpful to wear light-colored clothing because it's more easy to see the ticks and remove them.
Thirdly, to do tick checks when you're back indoors, to quickly remove any ticks that may be on you. Also, showering is very helpful with this. If the tick's not bitten, the showering often will remove ticks that are not embedded. And then there are repellents and actually insecticides that can be applied to your clothing, like permethrin. This can be very helpful. You can wear - you can spray it on your shoes, your boots, your socks, your pants. You can buy clothes that already have this - these compounds, permethrin, in them. So all those things are really great ideas just to protect yourself from the bite of ticks and mosquitoes. In your yard, you can tick-proof your property. You can do things like plant vegetation that are - that's not as attractive to deer. There's a lot of landscaping that you can do. We have all this information on our website. So I would just encourage you to go to our website, the sites that I provided. It'll give you a lot of pointers that you can use. But I'm sure the other speakers have a lot they can say about this as well.
RICK WEISS: Dr. Bartholomay, anything to add to that?
LYRIC BARTHOLOMAY:Sure. Well, I would just tag off of what Dr. Beard said and recommend that you look at the label of the repellent. But a step back, too, is that the EPA has a really nice decision-making site for the types of repellents you might want to use. And so you can use that resource from the EPA to choose a repellent based on the amount of time you anticipate being outdoors and whether you expect to be up against ticks and-or mosquitoes and what to do once you've put that on and getting it off. And so all kinds of really great tips available through the through the EPA on your choice of repellents. I think the other thing that we hear a lot is that, you know, this is - these are distressing things and people are concerned about their health and well-being. And some people will say to us, I'm just not going to go outside. And we certainly don't want to encourage that.
Being outdoors contributes tremendously to our well-being. So there's a lot of evidence base for that. Being outside is important. If you're concerned about mosquitoes and being outdoors, having a barbecue or eating with your family, one of the things that I recommend is that you consider just maybe even putting out those box fans. So this is one of the things that I like to do is just keep the air moving around the space where my family is when we're outdoors. I like the - I like mosquito coils, too. Some people like certain types of candles and things. Mosquitoes don't like a flame, so the fire could contribute to keeping the mosquitoes away to some extent. But I guess my bottom line is, be empowered by knowing that there are a lot of really great repellents out there that can protect you, and get outdoors.
RICK WEISS: Great. And Dr. Bottazzi, something besides improving the economic potential for someone to invent something great?
MARIA ELENA BOTTAZZI: Well, I think that this is where we have to ensure that we raise awareness where - especially using the example of the kissing bug for Chagas, right? These are big vectors, so learning how to recognize them, you know, making sure that you have access, you know, certainly through the website of the CDC or even the WHO, you know, that you can recognize these vectors. They have a very specific area where they live. Like, for instance, if you're out camping, you know, they usually hide in, like, shrubs. So you make sure you're - you know, you're camping in a cleaner area. You know, if it's - of course, in very highly endemic regions, it also is very depending on the fact that they live in very poor dwellings, right? So maybe here in the U.S., in some regions, we may have people who unfortunately still have very poor dwellings, so they hide in the cracks of your house. So there clearly are vector control activities that happen, certainly spraying for bugs in the infrastructure. So it's just, I think, raising the awareness to be mindful of being able to distinguish - right? - you know, what are these bugs and at least be alert and maybe know how to contact your local health officials and office to maybe even bring some of these bugs in that are able to then be able to be tested, evaluated and see whether there is a likelihood of that there is transmission.
RICK WEISS: Thank you. We are just about out of time here. I want to try to squeeze in one quick question, ask each of you if you have a five-second answer to this question. What do you think is the next big vector that's going to show up in this country that isn't here right now? Dr. Beard, do you want to vote for one?
BEN BEARD: Well, I don't know. I'm not sure. I mean, we - we're - it's a global village that we're in, and we're always concerned about people bringing ticks and mosquitoes and things back and the diseases that they carry. I don't have a crystal ball. I would just say we just need to be prepared and improve surveillance and diagnostic capabilities. But I don't have a crystal ball to say what might be on the horizon next. Sorry.
RICK WEISS: Smart guy not to guess. Anyone else want to throw out an idea of what we might see in the next few years that's not here now?
MARIA ELENA BOTTAZZI: Well, maybe I can just comment on not necessarily what we're going to see in a few years or not. I think we just should be very open-minded that we certainly - like Dr. Beard said, we live in a global world. We should not necessarily only focus of what we see now here. But there's a lot of changes, certainly in the Western Hemisphere, using the example, unfortunately, of high destabilization in Venezuela, for example. Clearly we're going to see more and more things probably moving up north as well as moving down south and moving east and west. So my message is really let's try to be more proactive and not reactive and try to find ways that we can develop potential global health solutions locally as well as globally, not waiting until a crisis happens before we start saying OK, let's now invest in, you know - right? Last, we have, unfortunately, a few examples, right? You know, the Ebola, when did we start really putting serious commitment? When we had Ebola here in the U.S., right? So I think it's raising the awareness that even if the problems are there today, they definitely most likely will come here. And we should start supporting - finding solutions now and not when this crisis occurs.
RICK WEISS: Great advice. Thank you. We are out of time. We still have some questions left. I'm sorry we couldn't get quite to all of them. I want to encourage everyone who's tuned in to look to our website over the next day or two, when you'll be able to see a complete transcript of everything that went down in today's session. I also want to remind you that we have an excellent fact sheet on our website on vector-borne diseases with a special section that's dedicated to what the science says with regard to the impact of climate change on the spread of vector-borne diseases in this country and a very good section that spells out what science has confirmed at this point and what is still unknown with regard to the relationship between climate change and the spread of vector-borne diseases.
One last point I want to make, besides the fact that you should all be following us on Twitter at @realsciline, is when you shut down from this media briefing, you will get a prompt to please take our survey. It's a really short survey. It's three questions. It's very helpful to us if you take that half a minute or minute to answer those three questions so that we can keep making these media briefings better and better to serve you. And finally, of course, if you're working on stories in this area, and you need to reach these or other experts in this field, we're the place to come to. We'll help you out and connect you to great experts to provide more details and context on this topic and others. So thank you very much for joining us. That marks the conclusion of this media briefing. And thanks to all three of our panelists for a great and really informative job today. Thank you very much.
In the United States, reported cases of human diseases caused by infected ticks, mosquitoes, and fleas tripled from 2004 to 2016. This increase is fueled by many factors, including climate-change related increases in rainfall, temperature, and extreme weather events that have enhanced the abundance disease-spreading vectors. Other shifts—in human land use and activity patterns—have also increased contact between people and infected organisms. The result is a growing U.S. public-health challenge. SciLine’s media briefing covered the status of vector-borne disease in the United States, projected future trends, associated health risks, and emerging research on methods for prevention and control.
Dr. Lyric Bartholomay, University of Wisconsin-Madison
Dr. Ben Beard, Centers for Disease Control and Prevention
Dr. Maria Elena Bottazzi, Baylor College of Medicine