Part A: summary of parameter values describing gametocytaemia in untreated infections, as fitted to 76 malaria therapy patients. Best-fit values were obtained for each patient, as described in the Methods section. The distributions stated here describe the large variation observed within the group of patients studied. In each case, four distributions were assessed for goodness of fit (normal, log-normal, gamma and Weibull distributions). We sample from these distributions to generate dynamics in our within-host model. The median value of
α
is 0.011, while the mean gametocyte maturation time is 7.6 days. Part B: best-fit parameters and units for the PD model, describing the rate at which AL kills gametocytes, as defined in Eq. (1). Parameter
is the maximum (max.) killing rate for drug
j
against gametocyte stage
. Eq. (1) shows how killing rates depend on drug concentration, with killing rates halved at the
concentration of each drug. For both drugs we retain the
concentrations fitted in a previous publication.14
A. Parameters governing the gametocyte dynamics | ||
Parameter | Distribution | Description |
α | Log-normal distribution ![]() ![]() | Commitment rate of asexual parasites |
![]() | Normal distribution, ![]() ![]() | Mean time spent in each immature gametocyte stage (in days) |
![]() | Normal distribution, ![]() ![]() | Mean circulation time of mature gametocytes (in days) |
B. Pharmacodynamic parameters for AL against gametocytes | ||||
Value for AM (95% credible intervals in brackets) | Value for LMF | Fixed or Fitted | ||
![]() | 0.18 | 0.13 | Fixed | Max. killing rate of stage 1 and 2 gametocytes (1/hour) |
![]() | 0.11 (0.09–0.12) | 0.04 | Fitted for AM, fixed for LMF | Max. killing rate of stage 3 and 4 gametocytes (1/hour) |
![]() | 0.08 (0.07–0.10) | 0 | Fitted for AM, fixed for LMF | Max. killing rate of stage 5 (mature) gametocytes (1/hour) |
![]() | 3.3 | 125 | Fitted previously for asexual parasites14 | Drug concentration (ng/ml) at which killing rate is half of its maximum |
AL, artemether-lumefantrine; AM, artemether; LMF, lumefantrine.