OVC Prof Combines Animal Health and Mathematics

Understanding disease dynamics key to infection control

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Prof. Amy Greer

Prof. Amy Greer

When equestrians take their steeds to a horse show, they may be focused on trying to win a red ribbon or two, or looking forward to seeing their friends and fellow competitors. From Prof. Amy Greer’s point of view, though, a horse show could be a high-risk situation.

“You have horses from many different places congregating at the horse show, and often they are housed together and have opportunities to be in contact,” she says. “Horses can be asymptomatic – appearing perfectly healthy – and yet have a contagious disease. So there are risks.”

Even worse, when the show is over and the horses go home, that prize-winning show jumper may carry the infection back to the other horses sharing his stable. It may be difficult to trace back to determine which horse brought the disease to the show premises.

Greer hopes her work can better inform our understanding of disease dynamics in animals and help us improve disease control and prevention strategies.

The Cobourg, Ont., native has found her way around North America, completing her undergraduate studies at Mount Allison University in New Brunswick, her master’s degree at Trent University in Ontario and her PhD in biology at Arizona State University, where she worked on infectious diseases of animals. From there, she did a post doc at the Hospital for Sick Children research institute in Toronto and was then hired by the Public Health Agency of Canada (PHAC). In January, she started in the Department of Population Medicine at Guelph’s Ontario Veterinary College.

At PHAC, her title was senior mathematician, something she found rather amusing since her degree was in biology. “I do, though, use math as a tool to think about and explore biological questions,” she says. While working at PHAC, Greer also had a cross-appointment, teaching grad students at the Dalla Lana School of Public Health at the University of Toronto.

“I develop mathematical models of disease transmission,” she says. “The model represents a potential explanation for a biological phenomenon. We can use the models to better understand how diseases spread as well as to test the potential impact of different disease control strategies.”

For example, she might create a model of influenza transmission and then see what happens if she added information to describe the implementation of a vaccination program, or information to capture the fact that some of those infected were given anti-viral treatments. Running those changes through the computer simulations suggests how those interventions might impact the health of the population.

“During my time at PHAC, there were a lot of public health questions about pandemic influenza: who should get priority for vaccination and how much anti-viral medication we might require in different circumstances.”

Each disease, of course, may be transmitted differently. For some diseases, just being in the same barn as a sick animal means another animal is highly likely to pick up the illness. In other cases, the animals need to be in close contact. In still others, contact with the infected animal’s bodily fluids is the key factor. Greer says all these differences need to be factored into the computer model.

Understanding how animals are kept, how they are moved from one place to another, and what infection control strategies might already be in place at a particular location are all essential bits of information that need to be added as well.

“Our limiting step is often data availability,” she says. “Our models can only be as good as our data, so we need to identify gaps and do additional research to create the best models.” The models will then be tested against real world situations to determine if the observations match.

While adding new research on animal populations, Greer is continuing some human public health studies as well. “We are looking at novel plant-produced vaccines,” she says. “Right now, influenza vaccines are grown in eggs, which takes a long time. A new technique has been developed to grow virus-like particles in plants inside a greenhouse. The data suggest this technology can produce more vaccine in a much shorter time. So my research is looking at what the potential benefits would be if we could have a pandemic influenza vaccine available sooner than the usual five to six months.”

Another potential benefit of these plant-based vaccines is that they may be more effective in seniors than the egg-based version. “The people most at risk from influenza tend to be older,” explains Greer, “but some seniors don’t mount a strong immune response after they receive the vaccine. Some early data on the plant-produced vaccines suggest they may have greater effectiveness among this group.”

Greer is enthusiastic about working at the University of Guelph; she sees many opportunities to collaborate on work with her colleagues. “I’m focused on meeting people and finding out about what they are working on to start identifying new areas for collaboration.”

At home she’s the mother of a busy two-year-old daughter. Greer says she is also a workout junky who has recently taken up running. And she and her husband, Mark, are busy working on a long list of DIY projects around their new home in Guelph.