What we are doing:  We are using mathematical modeling to explore and predict the spread of HIV and syphilis in Ontario. To do this, we use the best available data to build ‘virtual’ epidemics to test our ideas about the factors that make the situation better or worse. We are also conducting virtual clinical trials and evaluations of public health interventions for HIV and syphilis, such as pre-exposure prophylaxis for HIV and enhanced testing for syphilis.

Why are we doing this? HIV cases are not falling, and syphilis cases are on the rise in Ontario. New interventions, and better ways of delivering new and old interventions, are underway or under study in the real world. But it can be hard to measure the effect of the interventions on everybody. Mathematical – or simulation – models can help us explore entire ‘systems’ such as neighbouroods, cities or even the province.

For example, we explore the potential for pre-exposure prophylaxis to reduce HIV infections among those who are taking prophylaxis, and also among those who are not (a type of ‘herd immunity’). The models we are developing will be used to help inform decisions about what to do next to prevent HIV and syphilis infections in way that is sustainable, affordable, and most importantly – achieves the goal of improving one’s health and the health of our entire community.

Learn more in this ‘Raw Talk Podcast’ interview with Dr. Sharmistha Mishra about “what mathematical modelling can teach us about how and why HIV and sexually transmitted infections spread in various geographical areas.”

Our partners: At the Centre for Urban Health Solutions, we work alongside the Clinical HIV Prevention Unit led by Dr. Darrell Tan and Enhanced Syphilis Screening Among HIV Positive Men led by Dr. Ann Burchell. Our other partners include Ontario HIV Epidemiology and Surveillance Initiative, Ontario Ministry of Health and Long-Term Care (AIDS Bureau), REACH 2.0, Toronto Public Health, and Public Health Ontario. Our research is funded by the Canadian Institutes of Health Research and the Ontario HIV Treatment Network.


Mishra S, Fisman DN & Boily M.  The ABC of terms used in mathematical models of infectious diseases. J Epidemiol Community Health. 2011;65:87-94. Full text.

Pollock K. Nature. 531: S64–S66 (17 March 2016). Abstract.

For more information, please contact: Sharmistha Mishra at mishras@smh.ca