It was along the shores of Lake Michigan that Hanna Ehrlich, a postdoctoral fellow affiliated with the Center for Health and Wellbeing’s Global Health Program, found unexpected connections between the urban environment and the natural world. Ehrich was raised in Chicago, a city surrounded by and embedded in nature, which exposed her to these intersecting realms at a young age and eventually led her to the field of disease ecology.
In a recent interview, Ehrlich reflects on her academic journey and research focused on pathogen landscapes and the emergence and transmission of infectious diseases.
Q. What shaped your undergraduate education?
A. Exploring Chicago’s ravines and coastline, volunteering at the Field Museum of Natural History, and spending summers with the park district gave me an appreciation for the outdoors – even within urban and suburban landscapes. It was also very evident to me that not everyone in Chicago had equal access to these kinds of spaces. This made me think more critically about the blurred divisions between our built and natural environments, and how they can look very different to different people. These experiences inspired me to major in biology and environmental studies as an undergraduate [at Tufts University] and laid the groundwork for my interest in disease ecology.
Q. What were you initially planning to do with your degree?
A. I planned on going to veterinary school after college because I wanted to work with animals, and that felt like the obvious next step. But then I took a course on global health and security during my sophomore year, where I learned about zoonotic diseases for the first time. Honestly, it just clicked for me. I started thinking about the complex chains of transmission that bring animal diseases into human populations. I was fascinated by how multi-dimensional this process is, how it speaks to so many scales of our common world, from the cellular to the social and environmental. I also loved that it meant I didn’t have to study only one thing.
Q. Were there any other factors that influenced your decision to pursue a Ph.D. focused on the epidemiology of microbial diseases?
A. I had a few research experiences prior to graduate school that led me to pursue my Ph.D. I took a tropical ecology class that brought me to a biological research station in Costa Rica, where I studied these archaic-looking creatures called tailless whip scorpions. I spent a summer doing neuroscience research at the Korean Institute of Science and Technology. I also got involved in a student-led project called BUILD: India, a sustainable development initiative run in partnership with an NGO in South India. BUILD really exposed me to public health in a new and more nuanced way. All these experiences – combining lab work, field work, and some computational modeling – guided my graduate education [at Yale University].
Q. Why did you choose to do your dissertation on the surveillance and spread of drug-resistant malaria in sub-Saharan Africa?
A. Malaria is one of the oldest human diseases. While it isn’t zoonotic, it is vector-borne, making it climate-sensitive and closely tied to our environment. Unfortunately, we have only one combination drug that is effective in treating malaria, with little else in the pipeline. There’s a large concern that resistant parasites could spread from southeast Asia, where they are already prevalent, into sub-Saharan Africa, where most malaria cases exist. My dissertation project explored the surveillance systems and strategies to monitor the spread of drug resistance. It focused on Burkina Faso, a West African country, where partially resistant parasites have already been reported. The main goals of the dissertation were to analyze existing surveillance systems in place, track the spread of resistance through geospatial mapping, and improve monitoring efforts.
Q. What was most compelling about this research?
A. My research team tested an alternative approach to surveillance called “xenomonitoring.” After mosquitoes feed on humans, they fly around with human blood, or “blood meals,” in their midguts. Our goal was to collect these blood samples from the mosquitoes instead of sampling humans to get a better sense of what is being transmitted in the community. We vacuumed up the insects within community members’ homes and brought them back to our laboratories for analysis and mapping. Our findings demonstrated that this technique could be used as a complementary tool for tracking antimalarial drug resistance. Pairing creative approaches to surveillance with strong infrastructure at the municipal and regional levels could be a way to fill gaps in existing systems.
During my time in graduate school, I also came to note how the systems of research and intervention in global health have the potential to reinforce existing power differentials between the Global North and South. I started to consider the politics of science, like how funding mechanisms can dictate what types of questions get addressed and how. This led me to also get a certificate in the environmental humanities, focusing on the history of epidemiology and critical issues in the field.
Q. Tell me about your postdoctoral fellowship with the One Health Institute within the School of Veterinary Medicine at University of California, Davis (UC Davis). What was the focus of your work there?
A. The most exciting part of this opportunity was that I’d finally made it to veterinary school! After earning my Ph.D., I wanted to return to my initial passion of thinking about zoonotic diseases, and UC Davis had been at the forefront of that field for a very long time. UC Davis is a pioneer in the concept of One Health, or the connection between human health, animal health, and environmental health. The idea is that poor health outcomes in one of those dimensions affect the health of the other dimensions. I worked on two projects at Davis: one exploring the impact of deforestation on virus diversity in wildlife. The second project involved a serological analysis, identifying antibodies in human blood. We thought about how human behavior, livelihood, and ecological context could influence exposure to many different zoonotic viruses.
Q. What brought you to Princeton’s Center for Health and Wellbeing (CHW) and the Global Health Program?
A. Princeton’s fellowship opportunity came at an important juncture in my academic training. I have spent the last few years delving into ecosystems of zoonotic diseases on a global scale. I wanted to localize some of that work and add more mixed methods to my research, and Princeton is an amazing place to make that happen. In particular, CHW and the Global Health Program offer a uniquely interdisciplinary approach because the center sits between public policy, social sciences, and the natural sciences. This brings another dimension to my work, including attention to social problems and politics, while also providing access to Princeton’s world-class Ecology and Evolutionary Biology department.
Another essential piece of my decision to come to Princeton is that the university has a long history of working with Mpala Research Centre in Kenya, where I will be spending next summer. Stepping into a longstanding research site that has support, mentorship, and resources will help me advance my work and collaborate with people who already have close connections to local communities.
Q. What kind of field research will you do at Mpala?
A. I will be thinking about pathogen sharing and disease transmission between species, particularly large animals found at Mpala Research Centre and in the surrounding region. I’m especially interested in thinking about the ecological and social contexts where the exchange of pathogens happens.
We know, for example, that distribution of cattle plays an important role in disease transmission between cattle and wildlife. Meanwhile, the distribution of cattle is largely defined by who owns the land and how that land is managed. A better understanding of that landscape could help us develop interventions for keeping animals healthier while also benefiting those communities that are disproportionately impacted by higher disease burdens. That will be the basis of my overall research.
As part of this endeavor, I’m hoping to join a larger study centered around watering holes. The primary goals of this ongoing work are to monitor the animals at watering holes and to test for pathogens within the water, vectors, and the animals themselves. I am also interested in exploring why specific animals (livestock, rhino, and zebra) visit specific watering holes and asking questions related to land management, water insecurity, and potentially social and political dynamics.
Q. What has been most valuable about your visit to Princeton thus far?
A. My academic training has focused on health in global contexts. But people like Heather Howard [a professor at Princeton’s School of Public and International Affairs and co-director of CHW’s Global Health Program] have helped me think more about domestic policy. This has prompted me to reconsider the kind of work that I want to do and the impact it could have – how and whether policy at the local level could be scaled up.
Next semester, I will co-teach a course on principles of epidemiology. I’m excited to interact a lot more with students and, hopefully, to collaborate with them in my research at Mpala. I also will participate in the first cohort of the Future Values Fellowship at Princeton, which is designed to give faculty and postdocs in STEM a space to learn about critical, feminist, and science and technology studies, and to apply insights from these fields into our own work.
Q. Any thoughts regarding your career aspirations and future research?
A. There are a lot of different ways in which I hope to work on zoonotic diseases, whether that’s in academia or in more of a policy role. In either case, I would like to pursue epidemiological inquiries from a broader perspective, looking beyond the most proximal factors when thinking about questions of power, politics, and other upstream drivers of disease emergence and transmission. Whatever my career path, I hope to help make global health research more inclusive and participatory, aiming to design studies that are justice-oriented and built from the ground up. I believe it is important, within our research ecosystem, to consider who is collecting data, what is happening with that data, and how to ensure that the knowledge produced can benefit all impacted communities.
Q. What do you enjoy outside of global health? Any fun facts or interesting pastimes?
A. I enjoy traveling with my family, exploring the many cuisines of New Jersey and New York, political organizing, and helping with wildlife rehabilitation. I especially like working with injured birds. I also just signed up for a half marathon! While I’m not a great runner, it’s been a life goal of mine. I’m hoping that if we put it in this interview, I’m more likely to follow through.