Special Session 11: 

Effectiveness of control and preventive measures influenced by pathogen trait evolution: Example of Escherichia coli O157:H7

Xueying Wang
Washington State University
USA
Co-Author(s):    Majid Bani-Yaghoub, Patrick Pithua, and Sharif S Aly
Abstract:
This work is the first step towards assessment of control and preventive measures with respect to pathogen trait evolution.Our goal is to reassess the effectiveness of environmental decontamination (ED) and antimicrobial drug administration (ADA) by taking into account pathogen trait evolution within and between the hosts. To achieve this goal, we construct a multi-strain disease transmission model with cross immunity and intermittent shedding, where transmission occurs via environmental and host reservoirs. The ecology of infection is investigated by establishing conditions for stability and existence of equilibria.Using the stability results, it is demonstrated that pathogen trait evolution neutralizes or diminishes the effectiveness of ADA and ED. Specifically, first the model is fitted to the prevalence data of Escherichia coli O157:H7 in a dairy farm. Then the effectiveness of ADA and ED is explored under four hypothesized cases of pathogen trait evolution. It is shown that excessive implementation of ADA or ED can result in pathogen traits capable of destabilizing the disease free equilibrium and establishing stable multi-strain or single-strain endemic equilibria.