“From Clinical Practice to Research” — A Gateway to Tropical Medicine
Oshiro:
Dr. Kagaya, you pursued a career in tropical medicine after graduating from medical school. Could you tell us about your career path so far?
Kagaya:
I graduated from the Faculty of Medicine at Tokyo Medical and Dental University and went straight to graduate school without undergoing clinical training. Honestly, when I first entered medical school, I didn’t have a clear goal in mind. It wasn’t until my fourth year, when I had the opportunity to join a research lab, that I seriously started thinking about my career path. At that time, I happened to be assigned to a parasitology lab, and that led to an opportunity to go to Ghana.
Since childhood, I had a vague interest in Africa from watching documentaries, so when the chance to go to Africa came up, I thought, ‘If I can go to Africa, I want to go,’ and I joined the project. While there, I met people like medical officers from the Ministry of Foreign Affairs and researchers affiliated with the Japanese Society of Tropical Medicine. That’s when I realized that being a doctor doesn’t necessarily mean working in a hospital — there are various career paths available. That experience made me want to pursue tropical medicine.
Around the same time, the MD-PhD course started, and I thought, ‘If I can get paid while doing research, it could serve as a safety net.’ So, I decided to enroll in the MD-PhD program. In my fifth and sixth years, I continued with the regular medical curriculum, but my focus was primarily on research. I thought, ‘I’ll concentrate on research for now, and if it doesn’t work out, I can still pursue clinical training later.’ I felt that starting with research first would provide better continuity than going into clinical practice and then returning to research later.
Oshiro:
Your experience in Ghana seems to have been a major turning point for your career. Fieldwork experiences like that often provide impactful lessons that can’t be gained in a classroom, right?
Kagaya:
Yes, exactly. After that, I entered the graduate program at Tokyo Medical and Dental University. I was particularly interested in protozoa, and malaria was the most prominent research area, with plenty of opportunities for training. So, I chose malaria. In a way, it was a calculated decision.
At that time, the lab I was in mainly focused on schistosomiasis, not malaria. But my professor, Dr. Nobuo Ohta, was open to me studying elsewhere, so I came to the Institute of Tropical Medicine at Nagasaki University. Under the supervision of Dr. Osamu Kaneko, I received two years of molecular biology training, including genetic modification of protozoa and protein expression analysis.
Meanwhile, as someone with an MD background, I always had the desire to go to places where the diseases were actually occurring and interact with people. That’s why, after gaining foundational research training, I planned to move into fieldwork.
Just as my third year in the MD-PhD program was ending, Dr. Akira Kaneko from Osaka Metropolitan University (then Osaka City University) reached out to me. He was conducting field research in Vanuatu and Kenya and had just applied for a large research grant. He invited me to join the project, and right after completing graduate school, I began my fieldwork. That brings us to where I am now.
Oshiro:
I was a bit curious while listening to your career story. These days, going straight to graduate school after medical school is a rare choice. Was there anything you found particularly beneficial about taking that path?
Kagaya:
Looking back, I think it was the right choice for me at that time. I simply chose what I wanted to do at that moment. But even now, I often hear from other doctors, ‘You should have done clinical training first.’ The main value of medical school, in my opinion, is that it teaches you to see the patient as a whole. It’s hard to develop that perspective in a research lab. You really need to be at the bedside, interacting with patients, to acquire that kind of insight. Although I don’t have bedside experience, I try to keep that perspective in mind as much as possible.
Oshiro:
Indeed, clinical practice provides perspectives that can’t be gained solely through research.
Kagaya:
Yes, but at the same time, graduate school also gave me unique perspectives. For example, in medical school, we mostly deal with ‘humans.’ We rarely study other living organisms. In that sense, parasitology was almost the only chance I had to study other organisms. Gaining that perspective was invaluable to me.
In the doctoral program, I also interacted with many biology researchers. For them, humans are just one of many organisms. While I started my research thinking, ‘I want to eliminate malaria,’ some researchers were studying malaria as a fascinating organism in its own right. That kind of diversity in perspectives is what makes tropical medicine so interesting.
When working in the field, you also meet experts in economics, anthropology, hydrology, and other fields. Each person has a different area of expertise and a different way of thinking. These differences create incredibly stimulating conversations. For me, tropical medicine is a truly fascinating place because of that diversity.
Malaria Research – Exploring Various Fields
Oshiro:
Could you tell us about your current research and work?
Kagaya:
Currently, my work is almost entirely focused on malaria. Most of it is conducted in Kenya, but malaria epidemiology encompasses a wide range of areas. For example, we conduct intervention studies, as well as observational studies where we create cohorts to longitudinally track the same group of people to understand the state of malaria infections and transmission. Additionally, we also work on evaluating new tools, strategies, and diagnostic methods, often collaborating with companies to establish evaluation platforms.
Oshiro:
There really is a wide range of work even within malaria research. Speaking of intervention studies, how do you go about gaining the cooperation of local communities for your research?
Kagaya:
That’s a crucial point. Entering a new area requires understanding a certain “protocol” or framework. There is a specific order of whom to talk to, and it varies by region. It’s essential to grasp that structure, and honestly, it can be quite challenging.
For instance, in Kenya, the first step is to speak with the Ministry of Health and the Ministry of Education. And within these ministries, there are both national and regional levels that must be addressed. After that, we proceed to the local administrative officials and then to the village leaders. While such a structure exists, it’s not explicitly documented anywhere. It’s a kind of “unwritten rule.”
Therefore, each time we enter a new area, we rely on introductions from someone connected to that region to build relationships step-by-step. For example, when we recently started a new study on mycetoma in Senegal, a professor from Sudan introduced us to a contact in Senegal. That person then told us, “If you want to conduct research in this area, you first need to speak with this person.” And then that person connected us to someone else. It’s a continuous process of building connections and explaining our research objectives to ensure a conducive environment for the study.
Oshiro:
It sounds like quite a multilayered structure. That alone seems like a significant task.
Kagaya:
Yes, it is. Furthermore, when it comes to explaining the study to local communities, the content of the research is often quite complex. Communicating it in a way that is easy to understand is another significant challenge. Interestingly, we sometimes get unexpected questions from local residents. For instance, we are conducting a study using a ceiling-mounted mosquito net intervention, and we were asked, “How would you set it up in a house with this particular structure?” We had assumed a certain type of house structure, but in reality, there are considerable variations. Feedback like that helps us reassess the installation methods and improve our explanations.
Oshiro:
It really emphasizes the importance of being on the ground. Thank you for sharing such valuable insights. What do you find most rewarding or fascinating about your work?
Kagaya:
One of the most interesting aspects is the cycle of forming hypotheses and testing them while moving between the “field” and the “lab.” My background is in molecular biology, so I also work on molecular epidemiology, analyzing DNA and RNA from samples collected in the field. However, unlike a controlled lab environment, the field doesn’t have control groups, so we can’t directly establish causality. Statistical methods like causal inference are emerging, but essentially, the field is more about “hypothesis generation.”
For instance, we might identify a region with a high incidence of malaria and observe a correlation, but that alone is not enough to establish causality. That’s where lab work comes in — we can bring back samples and analyze gene functions, then return to the field to test those hypotheses. This cycle of hypothesis formation and testing is what makes the research so compelling and rewarding.
Another fascinating aspect is the interdisciplinary nature of the work. Recently, I’ve been collaborating with researchers in the humanities — particularly cultural anthropologists — on projects exploring the “anthropology of infectious diseases.” Since COVID-19, infectious diseases have increasingly been recognized as social issues, and we’re now looking into questions like, “How have people historically perceived infectious diseases?” and “What do infectious diseases mean to humanity?” We’re incorporating perspectives from history and philosophy to deepen these discussions.
Lastly, the opportunity to travel abroad is another significant draw. Meeting people from different countries, especially in Africa, and interacting with researchers from various backgrounds offer valuable opportunities to reconsider what a “country” or “nation” really means. I wasn’t particularly interested in international travel initially, but through research, I’ve come to appreciate the exposure to diverse perspectives. In fact, many researchers in tropical medicine entered the field because they love to travel.
Oshiro:
Traveling to various countries and meeting different people certainly sounds intriguing. Among the countries you’ve visited for field research, is there any place that left a particularly strong impression on you?
Kagaya:
Vanuatu definitely stands out. When people think of field research, they might imagine being in a rugged environment, but in Kenya, it’s actually quite comfortable — almost too comfortable. But Vanuatu was entirely different. It was genuinely tough; we had to walk for two hours straight, cross the sea instead of a lake, and the boat — well, it was more like a small, fragile dinghy — felt like it could sink at any moment. The waves were intense, and everyone was seasick.
Oshiro:
Were you okay?
Kagaya:
Well, I’m here now, so I survived! (Laughs) But honestly, there were moments when I wondered, “Why am I even doing this?” Experiences like that are rare these days. In the past, I imagine research and academia involved more of those “muddy boot” moments. Nowadays, the world is becoming more standardized, and such raw, adventurous experiences are becoming less common.
Expanding Connections with the World Through Research Activities
Oshiro:
Could you tell us about your dreams and goals for the future?
Kagaya:
I love writing papers, and I want to write as many good papers as possible. Papers serve as a record of one’s work and remain even after one has passed away. In other words, they become proof that says, ‘This is what I did.’ Through research activities and writing papers, I want to expand my sphere of influence and increase my connections with various people, things, and the world. That’s something I look forward to.
Oshiro:
In terms of research content, do you plan to continue with epidemiology, such as intervention studies? Or do you also want to conduct more basic research?
Kagaya:
In terms of research style, I’m more drawn to epidemiology and fieldwork than lab-based studies. In a lab, you try to set up all the conditions meticulously before proceeding. On the other hand, in the field, you start with imperfect conditions and uncertainties, and then figure out how to overcome them through analysis. That aspect feels more suited to me. Also, what I find fascinating about epidemiology is that the same data can yield completely different results depending on the analytical method used. Recently, approaches like Bayesian statistics and causal inference are becoming more common, and I enjoy thinking about how to apply these methods.
However, field research has its own challenges. Unlike in the lab, where you can redo experiments, fieldwork doesn’t allow for do-overs, so you have to be very meticulous in the design and preparation phases. Additionally, I want to continue doing what I genuinely want to do. While there is often a focus on social demands and practical applications, I increasingly feel that research is fundamentally a free activity without strict directives like ‘You must do this.’ Because of that, I want to cherish that sense of freedom and avoid setting too many boundaries for myself.
For example, the cluster randomized controlled trial (CRCT) I conducted in Kenya was a very fulfilling experience. I immersed myself in the field, experiencing intervention research firsthand, doing exactly what I wanted to do at that moment. Since it was a project based on my own interests, it naturally led to new research questions and subsequent studies. Before starting my own research, I had this image that research was something done ‘for someone else.’ But as I worked alongside various researchers in different settings—labs, fields—I started to realize the value and importance of enjoying my work.
Oshiro:
You mentioned that you primarily focus on malaria, but you also brought up mycetoma earlier. Are you looking to expand your research beyond malaria?
Kagaya:
Yes, I would like to. While malaria remains my core focus, I’ve recently started working on mycetoma, a fungal infection. It differs from malaria in terms of pathology and timeline, and the research methods and data interpretation also vary. Observing such differences is very interesting to me. Fungal research is still a relatively unexplored area, with plenty of research opportunities. I do try not to spread myself too thin, but having different areas of focus can also provide new perspectives. Moving forward, I want to gradually engage with other diseases as well.
Oshiro:
What do you think is the significance of Japan contributing to tropical medicine?
Kagaya:
There are several aspects, but one perspective that I heard from Professor Kido, whom I worked with at Osaka Metropolitan University, is the concept of ‘science and technology diplomacy.’ The idea is that conducting scientific research in other regions can also serve as a diplomatic tool to foster relationships and peace with other countries. I believe this is something Japan itself needs. Currently, many aspects within Japan are reaching saturation, and we may not be able to sustain ourselves solely within the domestic sphere. Thus, building international networks will become increasingly important.
In that sense, tropical medicine can be a powerful tool for engaging with Africa and other tropical regions. Ultimately, I think it’s about individual connections, and using science as a medium to form those connections is a very compelling idea. When we talk about Japan ‘contributing,’ it can sound as though we are only giving what we have to others, but in reality, the process is often more of a reciprocal exchange.
Oshiro:
Lastly, do you have any advice for members of the student section?
Kagaya:
I think it’s important to expose yourself to a variety of experiences. There’s so much out there that we don’t know. While discovering new things is fun, at some point, you also need to hone in on your specialty. Balancing those two aspects can be challenging, but if you keep exploring during your student years, you’ll eventually find that balance. So, instead of narrowing your focus too soon, keep an open mind and embrace as much as you can.
From left, Aika Kitamura, Yuma Yasunaka, Dr. Wataru Kagaya, Yukiko Aso, Kento Oshiro
Profile of Interview Participants
Wataru Kagaya
Assistant Professor, Department of Eco-Epidemiology, Institute of Tropical Medicine, Nagasaki University.
After graduating from the Faculty of Medicine at Tokyo Medical and Dental University, he pursued a direct path into research and obtained his PhD from the same university. He has been involved in epidemiological research on malaria, including intervention studies using ceiling-mounted mosquito nets. A father of one, he spends his weekends devoted to parenting.
Kento Oshiro
Fifth-year medical student, Faculty of Medicine, Kumamoto University.
President of J-Trops (Japanese Society of Tropical Medicine Students’ Branch).
Experiencing the COVID-19 pandemic sparked his interest in infectious diseases and global health. His hobbies include running, traveling, and reading, and his favorite book is Max Weber’s Politics as a Vocation.
