Mathematical Biology Seminar|
Ohio State University
Wednesday, February 1st, 2012
3:05pm in LCB 323
"Modelling Cholera transmission dynamics using identifiability and parameter estimation"
Waterborne diseases cause over 3.5 million deaths annually, with cholera alone responsible for 3-5 million cases/year and over 100,000 deaths/year.
Many waterborne diseases exhibit multiple characteristic timescales or pathways of infection, which can be modeled as direct or indirect transmission.
A major public health issue for waterborne diseases involves understanding the modes of
transmission in order to improve control and prevention strategies.
One question of interest is: given data for an outbreak, can we
determine the role and relative importance of direct vs. environmental/
waterborne routes of transmission? We examine these issues by
exploring the identifiability and parameter estimation of a
differential equation model of waterborne disease transmission
dynamics. We use a novel differential algebra approach together with
several numerical approaches to examine the theoretical and practical identifiability of a waterborne disease model and establish if it is
possible to determine the transmission rates from outbreak case data
(i.e. whether the transmission rates are identifiable). Our results
show that both direct and environmental transmission routes are
identifiable, though they become practically unidentifiable with fast
water dynamics. Adding measurements of pathogen shedding or water
concentration can improve identifiability and allow more accurate
estimation of waterborne transmission parameters, as well as the basic
reproduction number. Parameter estimation for a recent outbreak in
Angola suggests that both transmission routes are needed to explain
the observed cholera dynamics. I will also discuss some ongoing
applications to the current cholera outbreak in Haiti.