Figure 5.

Effect of IPT on parasite diversity. Blood concentration of drug during two treatments of IPT is shown. All of the sensitive parasites (white circles) initially present in the host at the start of IPT are killed by the drug, leaving only resistant parasites (black circles). While the drug concentration is high, new infections are prevented and the resistant parasites proliferate without competition. When the drug concentration falls below the threshold for sensitive parasites, an infectious bite can produce an infection with sensitive parasites. A subsequent bloodmeal may take up gametocytes from both sensitive (white crescents) and resistant strains (black crescents), thereby allowing out-crossing between them. At the next treatment, the sensitive parasites are killed and the resistant parasites continue to proliferate and may acquire new genetic material at the next cycle. Black arrows at the top represent continual biting by infectious mosquitoes.