1.The efficacy of chloroquine, quinacrine, quinine, and totaquine was tested against 79 induced infections of Plasmodium malariae (USPHS and Trinidad strains).
2.Chloroquine gave the best results. Quinacrine was better than quinine. Totaquine gave the poorest results.
3.P. malariae responded relatively slowly to all the drugs tested. Using similar chloroquine regimens, patients were fully cleared by P. vivax parasites in the peripheral blood much faster than of P. malariae, even though the densities of the P. vivax parasites were several times greater at the beginning of treatment.
4.No evidence was found that increased amounts of acquired immunity would aid anti-malarial drugs in the faster clearing of the blood stream from parasites.