Figure 3.

Plasmodium life cycle. The inner circle highlights key stages of the parasite life cycle targeted by malaria vaccines under development. Stages in italics represent biological bottlenecks where relatively few parasites (< 100) must be targeted to break the life cycle. (For comparison, the total number of merozoites/schizonts in the human host can exceed 10¹²). The outer circle shows the major classes of malaria vaccines under development Reprinted with permission from Elsevier: Ballou and Vekemans (20).