Fig. 2.

Existence of the disease-free and endemic solutions, and change in stability. (a) Two long term integrations of the ODE system (1) with initial conditions set to the disease-free equilibrium plus low amplitude random noise. Simulating aggressive testing and treatment rates of σ = 0.7, τ = 0.7 the disease-free equilibrium (dotted line) is stable throughout the simulation. Decreasing the parameters to the low coverage baseline scenario (σ = 0.008, τ = 0.14), the disease-free equilibrium loses stability and a stable endemic solution (solid line) appears. (b) We repeated the experiment starting with the endemic solution as initial conditions, again testing both sets of parameters. The endemic solution remains stable with the baseline parameters, and loses its stability and transitions to the disease-free solution in the aggressive testing and treatment scenario.