Figure 6

Modelling the effects of different infection rates on time-to-infection. Using the same model as in Figure 5, and assuming detection of infection by microscopy, we investigated the effects of raising or lowering the infection rate. The centre column (Highlighted, B, E, H,) shows the same infection rate as in Figure 5 (average time between bites = 10 days). Panel A shows the effects of a quadrupling of the infection rate. Similarly, Panel C shows the effects of a quartering of the infection rate. For each infection rate, the predicted time-to-infection curves for adults (red) and children (blue) are shown. Solid boxes in Panels A–C and solid lines in Panels D–I indicate an ‘early infection’ group, and dashed boxes and dashed lines indicate a ‘late infection’ group. The second row (D–F) shows the predicted difference in growth rates for children infected early versus late, at the different infection rates. Although at high infection rates (D) some difference in average growth rate is predicted, this is lost at lower infection rates. For adults, there is a large difference in growth rate between early- and late-infected groups at high infection rates (G). However, this difference is lost at very low infection rates (Panel I).