The growing threat of antimicrobial drug resistance presents a significant challenge not only to the medical community, but the wider general population. Alarmingly, resistant strains of infectious diseases are already endemic in many communities – particularly in developing countries and lower socio-economic settings – with new strains, which enjoy even more extensive resistance, continually emerging.
To examine this imminent threat to public health worldwide we implement a class of coupled, multi-strain epidemic models designed to simulate the emergence and dissemination of mutant (e.g. drug-resistant) pathogen strains. In particular, we investigate the ecological and evolutionary properties of a general class of multi-strain systems to determine e.g. the necessary and sufficient conditions for strain replacement/invasion, the relative contributions from amplification and primary transmission to the overall disease burden and the timescales involved. We also consider the evolutionary processes of various pathogens and investigate the rates at which both virulence and resistance evolve. This final point in particular predicates concerns about the ongoing arms race between the evolution of resistance and the development of novel treatments to treat new exotic strains – which many fear is being won by the former.