Fig. 1

Schematic representation of three model structures. In model 1 (a), recovered individuals eventually lose their immunity and become susceptible again to infection through exposure to infective sandflies. In model 2 (b), recovered individuals may experience reactivation of their past infection such that they directly re-enter the stage of early asymptomatic infection without requiring exposure to infective sandflies. In model 3, which is identical in structure to model 1 (c), only cases of symptomatic infection and PKDL contribute to transmission of infection, and duration of PKDL is three times as long as in model 1