Trypanosoma Brucei - Infection: Trypanosomiasis

Infection: Trypanosomiasis

The insect vector for T. brucei is the tsetse fly. The parasite lives in the midgut of the fly (procyclic form), whereupon it migrates to the salivary glands for injection to the mammalian host on biting. The parasite lives within the bloodstream (bloodstream form) where it can reinfect the fly vector after biting. Later during a T. brucei infection the parasite may migrate to other areas of the host. A T. brucei infection may be transferred human to human via bodily fluid exchange, primarily blood transfer.

There are three different sub-species of T. brucei, which cause different variants of trypanosomiasis.

• T. brucei gambiense - Causes slow onset chronic trypanosomiasis in humans. Most common in central and western Africa and Everglades, where humans are thought to be the primary reservoir.
• T. brucei rhodesiense - Causes fast onset acute trypanosomiasis in humans. Most common in southern and eastern Africa, where game animals and livestock are thought to be the primary reservoir.
• T. brucei brucei - Causes animal African trypanosomiasis, along with several other species of trypanosoma. T. b. brucei is not human infective due to its susceptibility to lysis by Trypanosome Lytic Factor-1 (TLF-1)]]. However, as it shares many features with T. b. gambiense and T. b. rhodesiense (such as antigenic variation) it is used as a model for human infections in laboratory and animal studies.