Figure 3.

Upper and lower bounds for each strain of the virus. In the absence of drugs (p=0), the wild-type virus dominates. As the fraction of adherence increases, the mutant may dominate. For a sufficiently high fraction, both strains have a basic reproductive ratio of less than 1 and hence the virus is controlled. However, there are regions where the upper and lower bounds of one strain interfere with the bounds of the other strain. In these cases, it is not possible to predict which strain will dominate and the outcome will depend on the patient's entire history of drug-taking.