Suramin is used as a primary agent in the treatment of African trypanosomiasis (African sleeping sickness; trypanosome fever) caused by Trypanosoma brucei gambiense or T. b. rhodesiense in patients with early or hemolymphatic disease without central nervous system (CNS) involvement. In patients with late stage or chronic trypanosomiasis caused by T. b. gambiense or T. b. rhodesiense involving the CNS, the primary agent is the toxic arsenical compound melarsoprol. Suramin may be administered as a preliminary agent prior to starting melarsoprol therapy in order to reduce the number of trypanosomes in the blood, thereby minimizing the adverse effects of melarsoprol. For patients who cannot tolerate melarsoprol, an alternative treatment is a combination of suramin and tryparsamide. These 2 medications are synergistic in action, and good therapeutic results have been obtained with combined administration. Eflornithine is another agent that has been found to be effective for T. b. gambiense infections. However, eflornithine has variable efficacy against T. b. rhodesiense infections. Suramin is used as a secondary agent in the treatment of onchocerciasis (river blindness) caused by Onchocerca volvulus . This agent is effective in killing the adult worm (macrofilaricidal) and also has partial microfilaricidal action. However, because of its intrinsic toxicity, suramin is now rarely used for this indication. Currently, its use is restricted to radical cure of selected individuals in areas without transmission of onchocerciasis, for expatriates leaving the endemic area, and for severe hyperreactive onchodermatitis in patients whose symptoms are not adequately controlled by repeated treatment with ivermectin. Ivermectin is considered the primary agent in the treatment of onchocerciasis as a microfilaricide; it has been shown to have little or no macrofilaricidal effect. or heavily infected patients, ivermectin may be given prior to suramin therapy to reduce the microfilarial load.