Host population structure impedes reversion to drug sensitivity after discontinuation of treatment
Fig 4
Description of infected population at the end of treatment.
a. Pairwise contacts at the end of treatment for all possible combinations of pairs involving at least one infected individual. For each infected individual its abundance in a host structures with σ2 = 24 and zero variance is reported both as observed at the end of treatment (obs.) and after randomisation of the infecteds (rand.). The abundance is given relative to the total number of pairs with at least one infected individual. b-e. Average degree of all infected (black), wild-type infected (red), and resistant strain infected (purple) individuals at the end of the treatment phase. Panel b shows the mean degree as a function of the degree variance in the network. Increasing variance in the degree distribution of the host network leads to a higher mean degree in the infected individuals. Individuals infected with the resistant strain show an even higher mean degree. Panel c illustrates the dependence of the mean degree on the treatment coverage. Panel d shows the mean degree as a function of the critical fraction of resistant infected individuals, fr. The advantage of a higher mean degree of the resistant strain vanishes with increasing critical fraction. In panel e we show the mean degree as a function of the rate of de novo emergence during the treatment phase. The trend of a higher mean degree of infected individuals with an even stronger signal for resistant infecteds is robust throughout a large range of de novo emergence rates, breaking down only for unrealistically high rates. If not specified otherwise, all simulations assume a degree variance of σ2 = 24 of the host network, full treatment coverage, c = 1, a drug efficacy of e = 0.5, and a de novo emergence rate r = 0.0001.