The Impact of Healthcare Delays on Infectious Disease Spread: A Simple Model

Nathaniel Osgood
Department of Computer Science
University of Saskatchewan

Abstract

Dynamic mathematical models of infectious disease characterize the spread of infection in the population over time. Such models have significantly improved understanding of epidemiological patterns, and assisted in the planning of health care policies in areas such as contact tracing, vaccination, and targeted interventions. While such models have offered great value, with a few exceptions they have ignored an important consideration in the context of many modern health care systems (including Canada's): The impact of limited human resources on the provision of health services. For some pathogens, the primary avenue to infection clearance is via treatment. The timing of such treatment can be significantly affected by shortages of human resources - due, for example, to slower contact tracing, or longer waits for treatment once a case is identified. Within this talk, we discuss the formulation and analysis of a simple mathematical model that characterizes the interactions between infection spread and waiting times. We begin with a brief demonstration of emergent model behaviour, which illustrates path dependence and lock-in. We then continue on to examine the mathematical structure that gives rise to such behaviour, examining the basic and effective reproductive rates R0 and R*, the location and stability of equilibria, and shifts in the severity of the epidemic and endemic prevalence due to staffing decisions. Analysis suggests that human resource staffing constraints can trigger "vicious cycles" in infection spread, that staffing levels can heavily impact epidemic prevalence levels, and that there are critical "tipping points" in staffing that can make the difference between elimination and persistence of a pathogen in the population.

April 28, 2008

Park Town Hotel

Cocktails 5:30, Dinner 6:00, Presentation 7:00

Tickets $20

For more information contact:

Kent Kostuk 244-3295 k.kostuk@fcl.ca

Winfried Grassmann 966-4898 grassman@cs.usask.ca