Chemotherapeutic approaches to protozoa: kinetoplastida--current level of knowledge and outlook.

The possibilities for treating haemoflagellate infections (African trypanosomiasis) are very limited (Table 1; Mehlhorn and Schrevel 1995; Croft 1997; Hunter 1997; Wang 1997; Trouiller and Olliaro 1998). All the available drugs have severe side-effects in humans and animals. Vaccination is not really an option, in view of the wide antigen variability. At present, there are several drug combinations in clinical trials: suramin/eflornithine, suramin/metronidazole, suramin/pentamidine, melarsoprol/pentamidine, melarsoprol/nifurtimox and nifurtimox/eflornithine. Some of these combinations were successful in treating resistant Trypanosoma brucei rhodesiense and/or T. b. gambiense infections (Keiser et al. 2001). In leishmaniasis, the tendency is still to resort to the old antimony compounds, with their severe side effects. At present, miltefosine is in clinical phase and is the first oral drug against visceral leishmaniasis (Jha et al. 1999). Two drugs are currently used against Chagas' disease, although these do not cure chronic effects. There is no prospect of novel drugs in this indication either (Pecoul et al. 1999; Morel 2000).