Haley Morris is writing her thesis, titled “Developing Mathematical Models for Host-Macroparasite Dynamics under Anthropogenic Global Change,” under the supervision of Péter Molnár in the Deparment of Ecology & Evolutionary Biology. She recently ranked among the 18 outstanding PhD candidates to receive a doctoral award from the Emerging & Pandemic Infections Consortium (EPIC), an integrated and interdisciplinary network of researchers and partners working to confront infectious disease challenges. 

We spoke to her about her research and what keeps her going.

Please briefly describe your thesis research.

My research focuses on trying to understand climate change impacts on host-helminth systems. Helminths are parasitic worms (e.g., tapeworms, roundworms or flatworms) that feed on a living host to gain nourishment and protection, while causing weakness and disease in the host. As the climate warms, habitats previously too cold for helminths become mild enough for them to survive, reproduce, and establish, which can lead to range shifts as helminths expand into these newly suitable habitats, and disappear from ones that have become too warm. Predicting these impacts before they occur proves challenging, because helminths remain relatively understudied. This means that there isn’t a lot of species-specific data that we can use to understand how climate change may impact the various traits and characteristics of these parasites, such as their spatial distributions or transmission dynamics. In the absence of data, theory can be a useful tool to understand climate impacts. So, for my thesis, I develop theoretical mathematical models (reaction-diffusion equations) to predict how climate change may influence host-helminth systems. With these models, I look at how rising temperatures impact key characteristics of the host-helminth system, such as mortality and reproduction, and the subsequent impacts on population and spatial dynamics, such as range shifts.

What do you hope to discover with your work, and what impact do you hope it will have? Why is this research important at the current moment?

There could be negative consequences as helminths shift their ranges. For example, range shifts could introduce diseases into new areas, exposing humans, wildlife, and the environment to diseases not previously present. So, by developing mathematical models that can predict climate change impacts before they occur, I hope they can serve as a predictive tool for identifying potential helminths of concern. We might, for example, be able to say which types of helminths may be more or less likely to shift their ranges in response to climate change. These predictions could then be used to develop proactive plans to monitor various regions at risk of helminth range expansion, or to assess risks to human, wildlife, and environmental health from helminths.

How did you become interested in your dissertation topic?

I did my undergraduate degree in EEB, and I’ve always been interested in how climate change impacts the environment, but my interest in parasites didn’t really start until I did an undergraduate thesis with Nicole Mideo to study how parasite evolution is influenced by host-population sex ratios. Once I completed my thesis, I took more coursework to learn about parasites and diseases and became really eager to find a way to combine my interests in climate change and disease; this led to me reaching out to my current supervisor, Péter Molnár, and the lab I’m in now.

How does having an EPIC doctoral award make a difference to your work?

The Emerging & Pandemic Infections Consortium (EPIC) is an interdisciplinary association of researchers from many departments and hospitals at the University of Toronto who study infectious disease. This means that as a part of the EPIC community, I get to network with and learn from experts and peers studying infectious disease from very different perspectives. Being exposed to expertise from a variety of fields provides me with unique opportunities to develop my skills as a researcher. The award also offers professional development support. As part of that, I’m going to attend a mathematical biology and parasitology conference in the summer, which will offer another great opportunity to meet others in the field and learn from distinct perspectives.

What do you do outside of research?

When I’m not thinking about climate change impacts on parasites, I’m often reading a book or hiking around the GTA. I really love checking out all the different conservation areas we have in the area, especially in the spring and fall.