Plasmochin simplex has rarely been referred to as a prophylactic against malaria infection in man or in birds, although there are many references in the literature to its effect on gametocytes in the blood stream and its potentialities in the prevention of malaria infection in mosquitoes, and thus indirectly in man. Hegner and Manwell (1927), by administering plasmochin (apparently plasmochin simplex), in daily oral doses of 1.5 mgm., to birds that had been inoculated with blood containing malaria parasites, kept the blood of one bird free from parasites for forty days, “with one possible exception.” Daily oral doses of 1.0 and 0.5 mgm. for five days after a single inoculation of blood containing malaria parasites did not prevent the appearance of parasites in the blood of birds.
Fischer (1927) and Ejercito (1929) have reported using plasmochin together with quinine to prevent malaria infection in man.
The experiments here reported were carried out at the Bureau of Science, Manila, in the Laboratory of Malaria Field Studies, with which the Rockefeller Foundation is coöperating. The author is a regular member of the field staff of the International Health Division of the Rockefeller Foundation.