WITHIN the past few years classic concepts of malaria have been modified by the addition of new knowledge. The details on different strains of Plasmodium vivax (benign tertian), discovery of tissue stages of P. vivax and P. falciparum, and discovery of new therapeutic agents have all added to our understanding of malaria and made rational treatment possible. The majority of these changes have come about through controlled tests in human volunteers, following careful preliminary work in animals.
The data on various strains of P. vivax have done much to aid our understanding of the relapse pattern of this type of malaria. Coatney and co-workers* have worked out the life pattern of the St. Elizabeth strain, a temperate zone malaria, and of the Chesson strain, a tropical strain originating in the South Pacific.
The Figure shows the relapse pattern of these two strains of P. vivax malaria in experimentally induced infections.