The delayed primary attack of vivax malaria.

DURING the war, American troops stationed in areas where malaria is endemic received quinacrine (Atabrine) or quinine for suppression of malaria, the vast majority receiving the former. A great number of these men were completely free of clinical manifestations of the disease throughout the period of suppression, but after the discontinuance of suppressive medication, the first attacks of malaria occurred. Nearly all the first, or delayed primary, attacks were vivax malaria.