THE ANTIMALARIAL ACTION IN DUCKS OF CERTAIN SULFANILAMIDE DERIVATIVES

1. Sulfanilamide derivatives such as sulfadiazine possess high activity compared to quinine in lophurae malaria in ducks when the comparison is based on minimal effective doses. However, these derivatives fail to reduce the parasitemia below 1 to 2% cells parasitized on the sixth day regardless of dosage when tested against an infection having a sixth day peak parasitemia in the controls. 2. The antimalarial action of sulfanilamides, such as sulfadiazine, is slower than that of quinine. 3. 3',5' Dibromosulfanilanilide and 3',5' dichlorosulfanilanilide exhibit a mode of action which differs qualitatively from that of ordinary sulfanilamides. 4. It is advisable to use minimal effective doses as the basis of comparisons of antimalarial activity.