Abstract: A method is disclosed herein for the treatment of parasitic diseases in animals such as birds and mammals, more specifically, in vivo and in vitro treatments of malaria, chagas disease and sleeping sickness with a compound comprising a unit of the formula:R.sub.1 --[--O--C.tbd.N]wherein the N may be single, double or triple bonded with respect to C, wherein R.sub.1 is one selected from the group consisting of alkali metals, ammonium and low molecular weight organo groups selected from the group consisting of alkyl, aryl, aroalkyl and allyl groups, whereby said parasitic infection is either reduced in severity or entirely eliminated. The compounds may comprise isocyanates, cyanate salts and carbamylphosphates.