Figure 5

Growth patterns for wild-type and piperaquine-resistant Plasmodium berghei ANKA parasites between D ₄ and D ₇ post-infection (pi) in the absence of drug. The parasitaemias were assessed at days 4 and 7 pi in the course of serial passaging of the respective parasite lines in mice for up to 18 serial passages in the absence of drug. The mean parasitaemias for the two parasite lines were different even at day 4 pi. At day 7 pi, the wild-type parasite had five times higher parasitaemia than the PQ-resistant parasite. It was also observed that untreated mice infected with the PQ-resistant parasite had slightly longer survival (>25 days) which was statistically significant (P < 0.05) relative to the wild-type and the LU-exposed parasite-infected mice with survival of up to 10 days. All the animals succumbed to malaria infection in the absence of treatment, with the mice infected with sensitive parasites (wild-type, PQS) dying by day 10 post-infection and those infected with resistant parasites (PQR) dying by day 28 post-infection.