Math Biology Seminar: Branching Processes in Evolutionary Epidemiology

  • Date: 11/17/2009
Helen Alexander (Queen's University)

University of British Columbia


The emergence of novel infectious diseases has become a major public
health concern, with zoonotic diseases such as avian and swine flu
providing prominent examples. Although initially poorly adapted to
their new host, such pathogens have the potential to adapt over the
course of a chain of transmissions and thus may cause a major epidemic.
In this talk, I will present a branching process model of the
between-host spread of an evolving pathogen. This stochastic model
allows us to address the probability of events such as evolutionary
steps and major epidemics, and identify risk factors influencing these


I will begin by reviewing single-type branching processes as applied to
disease spread, and then introduce a multi-type process that can
capture several strains of pathogen which may arise. Through a fairly
general framework, we can investigate the impact of contact
distribution in the host population and of the mutational pathway(s)
among pathogen strains on the probability of pathogen emergence
(adaptation and non-extinction). Time permitting, I will also present
preliminary results on the probability of specific strains arising and
the distribution of time to extinction or evolution.


2:00pm-3:00pm, WMAX 110

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