Figure 1.

Model structure. (a) Schematic for the treatment model that is used to motivate model (2.1). An individual can be susceptible (S), infected with a sensitive strain (I), infected with a sensitive strain and treated (T) or infected with a resistant strain (R). The dynamics of the treated class have been enclosed in dashed boxes to emphasize the difference between this figure and the equations for model (2.1). All analytic results are derived using model (2.1), which does not include the dynamics of the treated class. (b) Schematic for the detailed model. Using numerical simulations, the analytic results for model (2.1) have been extended to this more detailed model that includes the dynamics of the treated class.