University of Toronto Magazine University of Toronto Magazine
Illustration of a magnifying glass magnifying a mosquito, with mosquitoes on the left of the glass transforming into airplanes on the right.
Illustration by Sébastien Thibault

Predicting Where Infectious Diseases Will Strike Next

Climate change adds a new wrinkle in the quest to get out in front of epidemics

Spring arrives each year in Ontario with fresh concerns over diseases such as West Nile and Lyme, which flare up during warmer weather. If we could predict where and when an outbreak might occur, it would almost certainly make it easier to manage or prevent it. This is the Holy Grail of epidemiology, a cornerstone of public health that traces its roots to the Greek physician Hippocrates and now concerns people such as Isaac Bogoch, a U of T professor in the Faculty of Medicine and a tropical disease specialist at Toronto General Hospital.

A big challenge for epidemiologists is to identify the conditions under which a disease might spread. For certain viral diseases transmitted by tropical mosquitoes, Bogoch and his research group have developed a novel approach that combines the effects of climate change with data on airline travel and the distribution of mosquitoes that carry the disease. Using this model, his team has correctly predicted the extent of two recent, high-profile outbreaks.

In 2014, they identified the likely origin and potential spread in the Caribbean of Chikungunya, a mild African viral disease carried by mosquitoes. Using arrival and departure information from Caribbean airports, the model correctly predicted how the subsequent epidemic would affect 25 Caribbean islands, northern South America and Florida – all adopted homes of the mosquitoes that transmit the virus. Within six months, more than 16,000 confirmed and 900,000 suspected cases were logged, many of which might have been prevented if regional public health officials had been provided with the resources to act on the scientists’ predictions.

As the Chikungunya epidemic waned in the spring of 2015, Bogoch and his group began modelling the potential outbreak of another African virus spread by mosquitoes: Zika. Their study, published early the following year, showed the virus’s likely transmission patterns. Again, the study predicted the epidemic accurately: Zika raged through 50 countries in the Americas, infecting millions and prompting the World Health Organization to declare a global emergency.

As the international health community responded to the outbreak, Bogoch’s group developed a model for African and Asia-Pacific countries susceptible to Zika’s spread. They identified regions and times where the health, economic and social effects from Zika would be greatest so that public health authorities in resource-limited areas could be ready to respond should the disease appear.

The utility of such modelling is clear – as is the takeaway. “The reasons for these large-scale outbreaks are increased globalization, greater individual mobility and changing weather patterns – none of which are going away,” says Bogoch. “Increasingly, it isn’t about a new virus outbreak, but trying to figure out how those we already know about will expand into new territories.”

Recent Posts

Photo of front campus field and Convocation Hall with flower emoji illustrations floating above

Clearing the Air

U of T wants to drastically cut carbon emissions by 2050. It’s enlisting on-campus ingenuity for help

Abstract illustration showing a red-coloured body and face, with small black and white pieces flowing from inside body out of the mouth, and the U.S. Capitol Building dangling on puppet strings from one hand

The Extremism Machine

Online disinformation poses a danger to society. Researchers at U of T’s Citizen Lab are tracking it – and trying to figure out how to stop it

Prof. Mark V. Campbell with a beige background and red lighting

Charting Hip Hop’s Course

Professor Mark V. Campbell grew up during the early years of rap music. Now, he is helping preserve Canadian hip-hop culture for future generations

Leave a Reply

Your email address will not be published. Required fields are marked *

  1. One Response to “ Predicting Where Infectious Diseases Will Strike Next ”

  2. MARIANA GRINBLAT, M. Sc., M. Eng. says:

    This is a great article, and I think we should be aware of similar things that viruses can do! It's important to talk about climate change. It is a very imminent problem in Canada, as in the rest of the world. We need to take action as U of T grads, as scientists, as engineers, etc. I take public transit all the time, as I want to do my bit for the environment, the earth, my kids, grandkids and other Canadians. I hope they will do the same.