Trypanosoma lewisi
There are 2 hosts in the life cycle of trypanosomes; a blood feeding invertebrate and a vertebrate. Trypanosoma lewisi is found in the bloodstream of rats and is vectored by fleas. An infected flea takes a blood meal from a rat and then defecates passing metacyclic trypanosomes in the faeces. The rat licks the wound and also ingests the flea faeces. The trypanosomes penetrate the rat esophagous and enter the bloodstream. In the bloodstream they divide by multiple fission, forming rosettes of epimastigote forms. The rosettes break down, releasing the epimastigotes which transform to trypomastigotes. The trypomastigotes can remain in the bloodstream for several weeks and are infective to the flea. When ingested by a flea during a blood meal the trypomastigotes penetrate the stomach epithelium and multiply. New trypomastigotes are produced and released back to the stomach and can re-enter the epithelial cells for further division. Eventually, the released trypomastigotes will move to the rectum, transform into epimastigotes and undergo further multiplication to produce large numbers of infective metacyclic trypomanosomes.
This page © 2000. Dept. of Zoology, University of Manitoba.
