Ever-increasing complexities of diamidine and arsenical crossresistance in African trypanosomes.

The treatment of both human and veterinary African trypanosomiasis is still, to a large extent, dependent on diamidines and melaminophenyl arsenicals. Sixty years after the introduction of pentamidine, a large effort is being made to develop a new generation of diamidines for the treatment of sleeping sickness. However, given the reports of resistance to both diamidines and melaminophenyl arsenicals from the field, including crossresistance to both classes in single isolates, researchers should proceed with some caution before introducing new diamidines, and a thorough understanding of the causes of resistance and crossresistance will be essential.