Stochastic extinction of drug-resistant strains: Modelling the role of socio-economic factors in the pattern of extinction

Stochastic fluctuations in transmission may increase the probability of extinction of pathogens. While overuse of antibiotics leads to the emergence of new resistant strains in population by lowering its fitness cost, other socioeconomic factors may change the selection pressure and increase the probability of extinc- tion of the resistant strain. We develop a stochastic model of drug-resistance integrating socioeconomic growth in population to study the dynamics of extinction of resistant strain in the community, where it competes with the existing sensitive strain. We analytically derive the extinction threshold from the stochastic model using the multi-type branching process theory and obtain conditions for pathogen ex- tinction or persistence in population. Using numerical simulations, we compute the extinction probability, which shows a good estimate of values obtained from the branching process. Sensitivity analysis of the model also identifies parameters that have the most impact on the extinction of the strains. Although the transmission potential of respective strains plays a major role in extinction, our results illustrate that higher income, awareness, lower antibiotic use may increase the chance of extinction significantly by lowering antibiotic misuse. These analyses are beneficial to health policy makers and may quantify some parameters which are important to control the situation.