Development of new drugs against trypanosomes – a review of desirable properties of the drugs and potential drug targets in the parasite

The effective control of both human and animal African trypanosomosis has eluded mankind for decades. Vaccine production has been unsuccessful and prospects are poor apparently due to the ability of the trypanosome to change its antigenic coat and evade the host immune system. Vector control has environmental implications and has also not been successful in several areas. Drug therapy, which is the main method of control, has fallen back due to non-availability of new drugs. The existing drugs are not only old but have narrow spectra, toxic and difficult to administer. In addition, resistance to the drugs is widespread. The need to urgently develop new drugs is paramount if new outbreaks of the diseases are to be averted. Efforts to develop new drugs have been boosted by the completion of the T. brucei genome project. Application of RNA interference techniques has revealed several metabolic pathways that are unique to the parasite which can be targeted for drug development. The potential targets that have been adequately researched are reviewed here. The desirable properties of the expected drugs are also discussed