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Aman Chopra: Folks, welcome back to another episode of the "I AM GPH" podcast. Today we have Dr. Yesim Tozan, an assistant professor of global and environmental health here at NYU GPH. Dr. Tozan is a distinguished expert in health decision science, whose research focuses on the economics of infectious disease prevention and control. She leads groundbreaking projects in dengue surveillance, malaria treatment, and the impact of climate change on vector-borne diseases, working across diverse groups of regions, from Sri Lanka, Thailand, to Europe, and even Africa. I can keep going in the intro, but let's just hear from Dr. Tozan. Dr. Tozan, welcome to the "I AM GPH" podcast.
Yesim Tozan: Thank you so much for having me. I'm very happy to be here.
Aman Chopra: We're so excited to have you. I just, before the camera started rolling, I was asking you about what brought you to public health, when did you start your public health? It's been a long journey. So when people ask you that question, what brought you to public health? How do you usually answer it?
Yesim Tozan: I didn't start with public health. So that's the first thing that I'd say, because I'm trained as an engineer.
Aman Chopra: Oh, wow.
Yesim Tozan: Environmental engineering. So it wasn't necessarily a very conscious decision to go into public health sciences, but as you can imagine, environment has a close relationship to public health. But as a young engineering student, at the time, I started getting quite curious about environmental policy. So when I finished the engineering school, I started asking questions about, you know, how to get people comply with the environmental policies, like the private sector, what are the incentives? And then they told me that I'm kind of asking questions related to public policy. So that intrigued my interest. And the transition was a little slow because I was back in Turkey. That's where I am from. And I needed to continue with the, a little bit along the lines of engineering and environment. And I did my master's in environmental technology. That kind of opened up a little bit more into engineering and, you know, health connections. And then after that I realized that, you know, there are schools that are looking into policy and the larger field of public affairs. And I found myself at a school of public policy in the United States for a PhD program in science, technology and environmental policy. So, exactly...
Aman Chopra: Wow.
Yesim Tozan: It's a program that was suited for engineers who would like to get into the world of policy and, you know, public affairs. So that's kind of like the wandering way. But then, when I was at Princeton doing my studies, that was out of the, again, my interactions with my supervisor over there who wanted to kinda look in to this malaria problem in Africa through environmental management, the historical context of successful malaria control programs. And as part of my thesis, I started looking at that, by first spelling out malaria, and that was my introduction to public health and vector-borne diseases and specifically malaria.
Aman Chopra: We're gonna get deep into the whole vector-borne diseases, malaria, the mosquito-oriented stuff that you're working on. A lot of students, when they just heard your intro, or people watching this, have started from different places. We have had people on the podcast in nutrition. We've had chefs. We've had people that have come from completely different areas. But it all comes back to public health. What do you think are the commonalities with these people? You came from an engineering background, and you kept asking questions, "Ah, no, I want this, I want this." And it guided you into this direction. What's that thing in people that you notice in public health that brings them into this area?
Yesim Tozan: Everybody has a journey, I think, but the complexity of the problems and, you know, how people kind of seek solutions to those problems. And I was very much intrigued with the interactions, you know, of humans and the environments, and then, some of the problems, you know, that we encounter because of those interactions. And how to kind of remedy or find solutions to those problems. So my world was limited to environment and health and development, at the very beginning. But then, when I was introduced to a public health problem that is embedded in the environment, and on top of that, resource-constrained settings, I was quite intrigued. So in a way it was the complexity of the problem for me. And, you know, the historical efforts, when I started looking into the published works, and some of them are not necessarily scientific works. I read books about, you know, just written by people who experienced, you know, these health problems in the course of their experiences, for instance, when it comes to malaria on the African continent. And it was quite intriguing to me, and the complexity of the problem. But I think I have also seen in public health field where people were, in the past, professionals were a little bit of everything, to be able to address these public health problems. And, you know, they were epidemiologists, but they also, you know, used the data like a biostatistician, and they were interventionists, and they were at the same time working with the people to be able to get their buy-in into whatever, you know, measures that they were trying to put in. So they had this holistic view around the problem and what kind of gets involved with the solution of the problem. So before it was more like public works people kind of working with the people towards a goal, and that can be malaria control. And I think we have gone through some, you know, period where professions became much more well-defined. And, you know, medicine kicked in for certain health problems. And of course it comes with its own advantages, you know, treatments and to some extent prevention. But I think there was some sort of a divergence. And I feel like, I think people are, again, going back to understanding, you know, how are we gonna solve this problem, which is very much embedded, you know, in a much more complex system from people to economies to environments. And that has been, to me, the most interesting part of all of this, how do we bring all these pieces together?
Aman Chopra: I love hearing about this, how everyone, it comes to the same thing. Roles are getting defined now, but everyone has to start with a unique multifaceted path to get over there. I wanna talk about infectious diseases. You mentioned malaria a lot. When infectious disease comes up in most people's minds in the world, it might be Covid as the most recent example. What is malaria, what is dengue? What are these mosquito-borne diseases that you talk about, since your time goes deep into it?
Yesim Tozan: Those are vector-borne diseases, meaning that they are transmitted by a vector, in this case, for malaria and dengue, they're specific species of mosquitoes. And mosquitoes are as old as, you know, humanity. And they've been around and they persist and they survive. And they're the vectors for these diseases. And these diseases are quite prevalent in lower and middle income countries that are mainly in the tropical and subtropical parts of the world. And they were, at some point, malaria was also affecting more temperate regions, but it was possible to break the transmission in these regions through certain, you know, vector control methods. And because of the, you know, patterns, weather patterns, and continuous development, it was possible to get rid of malaria, specifically in temperate parts of the world. But a large proportion of the population is still suffering from these diseases. As I said, it's mainly confined to the subtropical and tropical areas of the world. And these diseases are very climate-sensitive because of the mosquito component. Temperature and rainfall patterns are very, very important in terms of determining the transmission intensity of these diseases in different parts of the world. And with climate change, dengue and malaria are becoming more of public health importance, because in certain parts of the world the transmission season is gonna extend because of, you know, increases in temperature, which favors, you know, mosquitoes' lifespan, and also speeds up its lifecycle, and also for the parasites that these mosquitoes carry, or pathogens within the mosquito, they also go through a much faster development period. So, all in all, I think we're gonna see quite a bit of an impact on mosquito-borne disease transmission in different parts of the world. You know, temperature rising in high altitude areas, that means that the disease is gonna climb up. In urban areas, certain species of mosquitoes can move in because of favorable situations, heat island effects in urban areas. And mosquitoes can be also quite invasive. We have seen an example of this. A mosquito species, mostly on the Indian subcontinent, moved in to Horn of Africa where, you know, it's causing outbreaks in urban areas, you know, malaria outbreaks, which is kind of like a new thing because, you know, we always thought of malaria as a rural disease, but the mosquito lives in the urban areas, this, you know, very highly adopted mosquito. And it's causing problems now in urban parts of Africa, in terms of malaria outbreaks. So it's fascinating, in a way, these interactions.
Aman Chopra: I'm fascinated by the climate change thing impacting the prevalence of mosquitoes in certain areas. For those people that don't know, not to get morbid, but what do malaria and dengue diseases like this do to people, so people know?
Yesim Tozan: Malaria is a disease that can be quite life-threatening in a short period of time if the person is not immune to it. And it's natural immunity, with exposure over time, that people get less and less sick when they're exposed to malaria. But it's a disease that affects children under five years of age. Those, you know, young years, where the child would be exposed to malaria and slowly develop immunity. But it is a very, very fragile span for a child. But once the immunity develops to malaria, then, you know, you see less sickness and less death. But it's a major public health problem for kids and also for women who are pregnant, and so, immunologically suppressed during pregnancy. So those are the two key target populations. And then, you know, you can also have outbreaks in different parts, you know, in different parts where overall the population is not exposed to malaria. And then you can have all age groups basically get affected by the disease. So that's malaria. And it's part of life in many places. It's a preventable and treatable disease. And yet we lose, you know, many children and many people to it every year. So it's certainly on the top of the list. Dengue is a different type of disease that is caused by dengue viruses. There are four different types. And it's a hemorrhagic disease. So it means that, you know, people affected by it would bleed, you know, internally. And it's also a disease with serious complications. For dengue, we actually don't have treatment. And the rapid diagnostic tests, or different types of tests, do work during certain stages of the disease. So it's mostly management of the case that makes sure that a dengue-infected person would survive. And over time, with multiple infections, also you can develop severe malaria. So it gets worse with the exposure. So the two diseases are quite different in terms of their long-term, you know, exposure to it. But anyways, you know, I'm more of a social scientist. This is the best that I could speak to the two diseases and their kind of clinical presentation in people. But dengue also affects young children. But I think its impact is broader on the population, as I said, over time. Multiple dengue infections can actually lead to more severe dengue in the person. So again, it's a disease that is quite prevalent in more urban settings of the tropical and subtropical areas. It has a quite strong connection to the environment and climate and human mobility, you know, as people move around. Because, you know, mosquitoes are all over, and people carry the, you know, whatever the pathogen, around with them, and the mosquitoes pick that up to transmit. So you can see dengue outbreaks, for instance, through the people who are traveling from dengue-endemic areas, to let's say some temperate parts of the world, and then we see outbreaks. Like we have seen outbreaks in Miami and, you know, in Florida in the past, and also in certain parts of Europe. So these diseases are also quite, you know, they go around, especially dengue, because of the vector's presence in different parts of the world.
Aman Chopra: What I'm curious about now, everyone is trying to solve climate change. Here, even at this school, people talk about it all the time. But this seems to be a more short-term solution that we need right now. So what are some ways that you are combating the mosquito challenge in your own research? I know you're working on something along those lines.
Yesim Tozan: One line of defense is, of course, mosquito control. And also it makes us, it puts us in a position that we can be prepared to respond to abnormal disease events, including outbreaks. So, in that regard, mosquito surveillance becomes an important component of any preparedness and response strategy. And understanding also the vector's connection with the climate so that we can get one step ahead of the mosquito and anticipate when its proliferation, let's say, is at its peak, and is causing, you know, risk. So for that, in my work, and this is very, very transdisciplinary work, or, you know, it's with the participation of quite a few who are in the public health field, from epidemiologists to entomologists to malariologists or, you know, people who are working on dengue, and, you know, infectious disease modelers, and then people like me who are interested in more on the policy aspects of disease control, we kind of come together to understand how to develop early warning systems and how to, you know, one step before then, how to understand these climate and disease associations. So some of the work that we have done over the past decade in these multidisciplinary groups is to use data available in different contexts to understand, you know, dengue climate associations, you know, malaria climate associations, and sometimes, whenever the data is there, we also kind of looked at the mosquito and climate associations to understand, you know, some of those relationships that would give us time to kind of get ahead of the mosquito, a couple of months or a couple of weeks, depending on the context, and inform preparedness strategies on the ground.
Aman Chopra: How would these strategies be implemented, then? So, those experts would handle it, once they have the information, how to combat the incoming mosquitoes?
Yesim Tozan: I am sure you have heard from many other people that you hosted in your podcast it's, you know, it's one of the hardest parts of doing public health related work. In this modeling work that we do, like any kind of, you know, work that is related to data, because we don't have all the data in the world, that there is uncertainty, you know, in the results. So it's very important to be able to communicate this uncertainty in your findings to a decision-maker who needs to act upon your findings, or whatever, let's say the early warning system might be telling you. So that's where the close work with the decision-makers and policy-makers, and this engagement with various types of stakeholders become important. The strong, long-lasting relationships in different contexts also become important, which kind of is a highlight of my work, that I try to develop those links through research projects, to stakeholders on the ground, with their participation. And it's always an opportunity for bidirectional learning because they really guide the research questions that we work on.
Aman Chopra: I want to take a step back with regards to finding the data, and preparedness, you know, preparedness of that these mosquitoes are coming in. What is it? I am thinking of 5,000 computers in front of you with a bunch of data. What does it actually look like to figure out that this is gonna happen, prediction, and things like that?
Yesim Tozan: The quality of that kind of work really depends on voluminous data, like longitudinal data, and also access to real-time data, so that you can continuously improve, you know, the models that are running under, like underlying these early warning systems. We started working on this, with the teams that I'm involved with, kind of, you know, going into one context and using the data and understanding these relationships and then, over time, you know, replicating the work in different settings and getting comfortable with the methods, and also capitalizing on the, you know, advancements in the field around these modeling techniques. And then, you know, you kind of arrive at something that you are more comfortable with, in terms of framework, and then, you know, using that framework in different areas. But it's really based on longitudinal, good quality data to give you the basis to understand these interactions. And one difficult part of this is that these interactions are so context-dependent. Is that you can, of course, see these general relationships between temperature and malaria or dengue. It is really, really important to kind of, you know, make those studies context-specific as well, to be able to respond to, you know, to different local settings. So I'm also very much interested in and committed to developing capacity in the methods that are used, you know, in the settings that we work. And one common thing, again, you asked the very early on question, what kind of is common across, I think, public health people who are working in public health is that this commitment to capacity development, that you just, you know, make sure that the tree keeps giving, you know? So we are also very much committed to developing this capacity because, as I said, these interactions are very locality-specific, and it's important to have that kind of capacity on the ground to, you know, continue with the work. And these, you know, changes at the local level, they're continuous, and it's important to take these changes into consideration and improve, you know, the models and improve the predictions moving forward.
Aman Chopra: I remember seeing something about, a long time ago, how Singapore was trying to get rid of mosquitoes completely.
Yesim Tozan: Yeah.
Aman Chopra: And then I saw this thing when I was looking you up about this mosquito drone project, bringing drones in the way of mosquitoes. It seems like these things are there to target mosquitoes. It's a war against mosquitoes, in a way. Can you tell me more about the mosquito drone project?
Yesim Tozan: That was not a project that I worked on, but I was part of a WHO, a TDR and an International Atomic Energy Agency, it was a technical advisory board that I was part of. And we were working towards developing a technical guidance manual for the evaluation of a specific mosquito control new technology. And during that time, in Mexico, I think the footage that you have seen, the drones were releasing mosquitoes into the environment, and those mosquitoes were sterile male mosquitoes that would then go on and mate with female mosquitoes. And then the offsprings, you know, would not be able to transmit, you know, the virus. So it was, again, an intervention that was envisioned. And then they were trying to see in that study site whether they would, these mosquitoes would be able to replace the wild, you know, male mosquitoes. And through that way it was a mosquito suppression method in the sense that, you know, the offsprings would die faster and without transmitting, but they would sustain the cycle without necessarily completely removing also mosquitoes from the system, in which, of course, they have a role to play in the overall food chain. So yeah, it was interesting because when I came back home from that trip, when I explained to my 4-year-old at the time, she completely understood this feedback system, and the role of mosquitoes and how important it is that they don't necessarily harm the humans, but we also do not take them out of the ecosystem because they're food for, you know, some other species. And it's important to keep them alive, but not necessarily, you know, that they're harmful to people. So when I described this to my daughter at the time, she completely understood the project. You know, instead of mass destruction, it's more like trying to find a way to exist.
Aman Chopra: Yeah.
Yesim Tozan: With the mosquitoes without necessarily having the harmful, you know, public health issues that originate from them.
Aman Chopra: Sounds like mass creation.
Yesim Tozan: Oh, well, yeah, it's preserving, preserving them, you know, in their capacity without necessarily being harmful, yeah.
Aman Chopra: A lot of students might have been listening to the longitudinal data stuff, how you're gathering data with mosquitoes. Can you tell me about your lab and what's prompted you to start this lab for students that might wanna work with you or might want to get into this field?
Yesim Tozan: The several projects that I was involved with, provided an opportunity to be able to have our students participate in the research projects. So then I needed like a roof, you know, for everyone to gather under as they participated. And I think that we came up with the name of the lab as we were flying to Sri Lanka for a dengue project. And it was interesting. And then, you know, Health Economics Learning Lab came to the mind, and then I liked the acronym H-E-L-L, Hell, so that was the main attraction as well. But it was really out of necessity to, you know, kind of formalize the relationships that I have with the students and with other researchers from other academic or non-academic institutions to kind of, you know, have a house at GPH. And it's a very, very research-heavy lab, in the sense that it attracts students who would like to involve with research projects. And it has a very broad scope, not only vector-borne diseases, but whatever research project I pick up on with teams, then, you know, and then if there is a need, you know, in the project, and that need can be met with a master's or doctoral student at GPH, then, you know, the doors are wide open.
Aman Chopra: I'm curious to know some projects that students have done that excited you or impressed you in the past?
Yesim Tozan: Well, with different partners, academic partners, we've evolved into different projects. For instance, in Uganda, through, again, one of the trainees that I have from the NIH-funded training program, who was on the ground in Uganda and also originally from Uganda, had this relationship with the hospital that he worked at. And the hospital was very good at their record-keeping. And they had this longitudinal data on their patients, and they really wanted to improve their case management. And at the same time, some of the doctors were also trained, they were clinician-researchers, but they didn't have all that much time to be able to work with the data that they were painstakingly gathering on their patients and storing at the hospital database. So they came to us with questions. For instance, colorectal cancer that they were seeing in their patients, but then they were seeing it in younger patients in Africa as opposed to other parts of the world. And they had legitimate questions. And, you know, some students kind of looked into that and used the data that was provided by the hospital. And, you know, we had our weekly meetings where we refreshed or shaped the research question and did the analysis and presented at different, you know, findings at different conferences. And the students were really at the forefront of that as this was a project that just, you know, sprung up because of the need, and also because of, you know, doctors on the ground really realizing that there's something going on there that they wanted to look at more carefully with the data.
Aman Chopra: I wanna close on this question, because your work is fascinating, and it seems like it requires a lot of people, a lotta, lotta people. You said once that you were the maestro of the orchestra. Can you tell me what that means?
Yesim Tozan: Because I kind of hopped around a little bit, you know, into different fields. I really like listening and thinking alongside people and hearing their perspectives around a question, and in working with them to shape the research question. And also kind of record-keeping, almost, what I hear from people who are engaged with one aspect of the problem, and then how that comes together. In a way, I find it as my own personal challenge. Like around a complex problem, how the solution would look like, the multifaceted, and trying to get people around, you know, understanding the problem better, and then, you know, kind of formulating a research question, and then still not losing the entire team and having them contribute as we try to answer that research question. So that's where I find it most rewarding to me, the process, sometimes regardless whether, you know, we go in a successful direction. So most of the time we seek funding, you know, for the research projects that we develop. But that's not really where, I just really like this learning with everyone, and then formulating a research question all together. And then, you know, laying the steps towards how to. And then building a team, you know? Usually you need more, you know, it's like you also need to make the connections where the research project would take place, and reaching out to those folks that would provide, you know, the setting, the technology. All those parts are really very exciting to me in a research project. So I don't know whether it makes sense...
Aman Chopra: No, it absolutely does. It seems like you bring people and what they're best at and you make sure everyone's collaborating in the best way possible for themselves and the bigger picture, and that's what makes you the maestro of the orchestra.
Yesim Tozan: Yeah, or that's what I aspire to be. Whether I would get to the level of a maestro, but this is where I would like to, kinda as the years pass, focus my energies on. And providing a platform through this, you know, to new generations, right? It's like the new early career researchers, so that they can take it and, you know, take it away, in a way. Pick it up and take it away. So that's why the reward happens for me.
Aman Chopra: So, Dr. Yesim, I want you to leave everyone with this. What's next for you in your public health journey? You've been in this industry for decades at this point. What's happening next for you? What are your next steps when you think of public health?
Yesim Tozan: Well, as I said, I am very much energized by the people. And when I meet groups on the ground and talk to them, what is, you know, troubling, what is the next, you know, big challenge, hearing, and then from the people and working with the people, to be able to get at those important problems. But, of course, climate change is hovering all of us, and, you know, we are feeling the impacts in different ways and from our lives, you know, wherever we are too, and also its impact on some of the public health questions, persistent public health questions. So I think that's pretty much on my radar to continue the work that we have accomplished, or on the heels of the work that we have done. And non-communicable diseases and mental health issues are also getting very close to my heart. They also have quite a bit of interactions with infectious diseases as well. And also, you know, on the lookout always for efficiencies and synergies and, you know, where all these diseases kind of converge in terms of service delivery. Those are, again, tough questions to get at. How to tackle a variety of public health problems under the impact of climate change. So, you know, those kind of integration questions, service integration, in resource-constrained settings. So I'm kind of headed over there, over that direction. And climate change is quite a big focus as well in my research.
Aman Chopra: Well, thanks for being on the episode, Dr. Yesim Tozan. I'm excited to see how your multifaceted approaches impact the public health world, from mosquitoes to human beings. Thank you for sharing all your insights.
Yesim Tozan: You're very welcome, thank you for having me.
Aman Chopra: Our pleasure. That was Dr. Yesim Tozan, everybody. You have any thoughts, put it in the comments down below. We'll link all the work that Dr. Tozan has done. And thanks for tuning into this episode. We'll see you in the next one.