Fig. 1. Parasite multiplication rates in a panel of 24 new Ghanaian P. falciparum clinical isolates over five months of continuous culture.

a Exponential multiplication rates per 48 h at the first assay timepoint (after 25 days) were successfully determined for 18 of the isolates, showing a mean multiplication rate of 4.3-fold, with a wide range among the different isolates. Multiplication rates of the clinical isolates increased over time, with a mean of 5.1-fold after 77 days (assay of 23 isolates) and 6.4-fold after 153 days (19 isolates) (Mann–Whitney test, P = 0.0009 for day 153 versus day 25, and P = 0.015 for day 77 versus day 25, P = 0.042 for day 153 versus day 77). The exponential multiplication plots with experimental replicates for all isolates are shown in Supplementary Fig. S1, all numerical data are given in Supplementary Data File S1, and 95% confidence intervals of the estimated multiplication rates based on logistic regression of the experimental replicates are given in Table 1. b All except one of the 15 isolates that were tested at both the first and last timepoints had an increased multiplication rate at the last timepoint (Wilcoxon rank sum test, P = 0.0002; dashed line of equivalence shown) although wide variation among the isolates remained.