Trypanosomatids: Odd Organisms, Devastating Diseases

Abstract

Trypanosomatids cause many diseases in and on animals (including humans) and plants. Altogether, about 37 million people are infected with Trypanosoma brucei (African sleeping sickness), Trypanosoma cruzi (Chagas disease) and Leishmania species (distinct forms of leishmaniasis worldwide). The class Kinetoplastea is divided into the subclasses Prokinetoplastina (order Prokinetoplastida) and Metakinetoplastina (orders Eubodonida, Parabodonida, Neobodonida and Trypanosomatida) (1,2). The Prokinetoplastida, Eubodonida, Parabodonida and Neobodonida can be free-living, com- mensalic or parasitic; however, all members of theTrypanosomatida are parasitic. Although they seem like typical protists under the microscope the kinetoplastids have some unique features. In this review we will give an overview of the family Trypanosomatidae, with particular emphasis on some of its "peculiarities" (a single ramified mitochondrion; unusual mi- tochondrial DNA, the kinetoplast; a complex form of mitochondrial RNA editing; transcription of all protein-encoding genes polycistronically; trans-splicing of all mRNA transcripts; the glycolytic pathway within glycosomes; T. brucei vari- able surface glycoproteins and T. cruzi ability to escape from the phagocytic vacuoles), as well as the major diseases caused by members of this family. However, the present review does not cover all trypanosomatids; for example, the in- sect trypanosomatids are underrepresented here. On the other hand, reviews on this particular group of parasites have been written by experts in the field (3-12).