A mathematical model with nonlinear relapse: conditions for a forward-backward bifurcation

ABSTRACT

We constructed a Susceptible-Addicted-Reformed model and explored the dynamics of nonlinear relapse in the Reformed population. The transition from susceptible considered at-risk is modeled using a strictly decreasing general function, mimicking an influential factor that reduces the flow into the addicted class. The basic reproductive number is computed, which determines the local asymptotically stability of the addicted-free equilibrium. Conditions for a forward-backward bifurcation were established using the basic reproductive number and other threshold quantities. A stochastic version of the model is presented, and some numerical examples are shown. Results showed that the influence of the temporarily reformed individuals is highly sensitive to the initial addicted population.

KEYWORDS:

• Nonlinear relapse
• backward bifurcation
• epidemic models
• social determinants
• addiction

Acknowledgments

The authors would like to thank the support from the Research Center in Pure and Applied Mathematics and the Department of Mathematics at Universidad de Costa Rica.

Disclosure statement

No potential conflict of interest was reported by the author(s).