Trypanosome
From Freepedia
| Trypanosomes | ||||||||
|---|---|---|---|---|---|---|---|---|
| Image:Trypanosoma cruzi crithidia.jpeg Trypanosoma cruzi parasites | ||||||||
| Scientific classification | ||||||||
| ||||||||
| Genera | ||||||||
|
Blastocrithidia |
Trypanosomes are a group of kinetoplastid protozoa, distinguished by having only a single flagellum. All members are exclusively parasitic, found primarily in insects. A few genera have life-cycles involving a secondary host, which may be a vertebrate or a plant. These include several species that cause major diseases in humans.
The most notable trypanosomal diseases are sleeping sickness, Chagas disease, and leishmaniasis. These first two are caused by species of Trypanosoma and the last by Leishmania, which are the main genera that infect vertebrates. Species that infect plants are classified as Phytomonas.
A variety of different forms appear in the life-cycles of trypanosomes, distingished mainly by the position of the flagellum:
| Amastigote (leishmanial) | - reduced or absent |
| Promastigote (leptomonad) | - anterior of nucleus, free from cell body |
| Epimastigote (crithidial) | - anterior of nucleus, connected by a short undulating membrane |
| Opisthomastigote (herpetomonad) | - posterior of nucleus, passing through a long groove in the cell |
| Trypomastigote (trypanosomal) | - posterior of nucleus, connected by a long undulating membrane |
All trypanosomes have at least amastigote and promastigote stages. Trypanosoma appears in all five forms, with the trypanosomal stage occurring in the vertebrate host.
