Trypanosoma lewisi

Species of parasitic protozoan

Trypanosoma lewisi is a globally distributed parasite of Rattus species and other rodents such as mice, and of kangaroo rats in America. Among these host species were two endemic species of rats: Rattus macleari and Rattus nativitatis. Both are now believed to be extinct. It is not very clear whether or not the same parasite infected both species. However, both parasites are very similar. The northern rat flea acts as the vector for the parasite, harboring the epimastigote stage in its midgut. The trypomastigote is the stage that is present in the main host, the rodent. The epimastigote form attaches itself to the rectum of the insect using its flagella to burrow through the rectal walls. The parasites also appear in the flea's feces. Ingestion of either the flea or its feces during grooming infects the host rodent with the parasites. T. lewisi is normally non-pathogenic but is known to have produced fatal infections in rats.

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