Hycanthone resistance: development in Schistosoma mansoni.

Following the administration of relatively high doses of the antischistosomal drug hycanthone to mice and hamsters infected with Schistosoma mansoni, a number of the worms survived. After a period of 6 to 12 months these parasites resumed production of viable eggs that gave rise to schistosomes that proved resistant to hycanthone and to two other related antischistosomal compounds. This drug resistance has remained stable for three subsequent generations of worms.