Chemotherapeutic agents against pathogenic animal trypanosomes

Abstract

Trypanosomoses are protozoan diseases, affecting both human and animals, and mainly found in tropical Africa, Latin America and Asia. In Africa, trypanosomes produce serious diseases in human beings such as West and East Sleeping Sickness caused by T. brucei gambiense and T. brucei congolense respectively, while in the Americas T. cruzi causes the Chagas disease. Other species of Trypanosoma affect animals and produce enormous economical impact in the endemic areas. Those species could be classified as those transmitted by tsetse flies- (Trypanosoma vivax, T. congolense and T. brucei brucei) producing a disease known as nagana and those non-transmitted by tsetse- (T. evansi –surra-, T. equiperdum–dourine-). Due to antigenic variation shown by the trypanosome, prophylaxis of these diseases using vaccines is challenging; for that, most of the control and eradication programs against animal trypanosomes carried out in the infected areas in the world are based on therapeutic and prophylactic measures, using trypanocidal drugs or combining both measures. However, only three compounds are available in the market (isometamidium chloride, homidium –bromide and chloride- and diminazene aceturate) and all of them have been on the market for over 40 years. One of the most important risks for the future use of these existing trypanocides is the development and dissemination of resistances and, for that, new drugs have been developed in the recent past and are available in the market to treat T. evansi (melarsomine) and, on the other hand, new anti-trypanosomes candidates are being developed and tested at clinical trial level presently. The aim of the present chapter is to review the current status of the therapeutic and prophylactic agents used for the control of pathogenic animal trypanosomes as well as the potential candidates that are tested nowadays as possible new trypanocides to be used in the next future.