A composition comprising from 0.02 to 17 parts by weight of glycerol per part by weight of an iron chelating agent selected from the group consisting of salicyl hydroxyamic acid; 2,3- and 3,4-dihydroxy benzoic acid; and halobenzohydroxamic; e.g., m-iodobenzohydroxamic acid and m-chlorobenzohydroxamic acid; as well as their C.sub.1 to C.sub.4 alkyl esters. When this composition is administered parenterally, it is found to block aerobic and anaerobic glucose catabolism and thereby accomplish control of several trypanosomes, including Trypanosoma brucei, T. gambiensi, T. rhodesiensi, T. equiperdum, T. evansi, T. congolense and T. vivax. In mammals, the therapeutic dosage is calculated to provide at least 138 mg/kg of body weight of glycerol and at least 96 mg/kg of body weight of the iron chelating agent.
