Establishment of the initial parasitaemia after magnetic column purification. Plasmodium falciparum iRBCs isolated with magnetic columns were adjusted to 0.2% haematocrit and different parasitaemias (1, 5, 10, 15, and 20%). Plasmodium falciparum cultures were harvested after 18 hours to determine the parasitaemia levels. A. Giemsa-staining smears from cultures purified by magnetic purification and allowed to reinvade new uRBCs. B. Parasitaemia achieved at 0.2% haematocrit with the different initial parasitaemias tested was estimated from blood-smears (n = 3). C. Invasion rate calculated accounting for the parasitaemia obtained after 18 hours (final parasitaemia) and the initial parasitaemia of the P. falciparum culture (final parasitaemia/initial parasitaemia). This rate indicates the capability of the parasites to invade new RBCs.