α-Difluoromethylornithine: A promising lead for preventive chemotherapy for coccidiosis

SUMMARY α-Difluoromethylornithine ( dfmo ; RMI 71,782) given in drinking water in concentrations as low as 0.0625% inhibited infections of Eimeria tenella and minimized the development of lesions in chickens. It had approximately the same activity as a currently used anticoccidial drug, amprolium, and also had the advantage of being relatively nontoxic in chickens. Body weight gains were not reduced in chickens given 0.0625% dfmo or less for 14 days starting 8 days before they were inoculated with oocysts, but were reduced in chickens given drinking water containing 0.125 and 0.25% dfmo . The anticoccidial activity of dfmo was completely reversed by injection (intraabdominal) of putrescine hydrochloride (300 mg/kg of body weight/day), indicating that the drug may act by blocking putrescine biosynthesis. Inoculated chickens, in which coccidial lesion development was suppressed by dfmo , resisted subsequent challenge exposure with E tenella , as did nontreated infected control birds which had recovered from infection.