Trypanosoma brucei
Parasite causing sleeping sickness and nagana in sub-Saharan Africa.
Trypanosoma brucei is a species of parasitic kinetoplastid belonging to the genus Trypanosoma, present in sub-Saharan Africa. It causes deadly vector-borne diseases: African trypanosomiasis (sleeping sickness) in humans and animal trypanosomiasis (nagana) in cattle and horses. Unlike other protozoan parasites that normally infect blood and tissue cells, it is exclusively extracellular and inhabits blood plasma and body fluids.
- field
- Parasitology, tropical medicine
- known_for
- Causing African trypanosomiasis (sleeping sickness) and nagana; antigenic variation via variant surface glycoproteins; crossing the blood-brain barrier
Lore & Background
On the sixth day of investigation, Bruce identified parasites from the blood of diseased cows, initially noting them as a kind of filaria, but by the end of the year established they were protozoan and the cause of nagana.
Reader's Guide
Trypanosoma brucei is significant as the causative agent of African trypanosomiasis (sleeping sickness) in humans and nagana in animals, diseases that have caused major epidemics in sub-Saharan Africa. The parasite is transmitted by tsetse flies (Glossina) and undergoes complex morphological changes between insect and mammal hosts. Its mammalian bloodstream forms feature variant surface glycoproteins that undergo remarkable antigenic variation, enabling persistent evasion of host adaptive immunity and leading to chronic infection. T. brucei is one of only a few pathogens known to cross the blood-brain barrier. Current treatments can have severe side effects and can prove fatal, creating an urgent need for new drug therapies. The species complex includes five subspecies, with T. b. gambiense and T. b. rhodesiense causing human disease.
Did You Know?
- T. brucei is one of only a few pathogens known to cross the blood-brain barrier.
- The parasite undergoes complex morphological changes as it moves between insect and mammal hosts.
Frequently Asked Questions
Who is Trypanosoma brucei?
Trypanosoma brucei is a parasitic kinetoplastid protozoan endemic to sub-Saharan Africa that lives exclusively outside host cells, drifting freely in blood plasma and other body fluids. It is the causative agent of African trypanosomiasis (sleeping sickness) in humans and nagana in cattle and horses.
What are Trypanosoma brucei's powers/role?
Its signature trick is antigenic variation: it continuously swaps the glycoproteins on its surface coat to stay one step ahead of the host's antibodies. It can also breach the blood-brain barrier, a capability that very few other parasites possess and that makes the disease so lethal once the central nervous system is involved.
How does Trypanosoma brucei's story end?
Without treatment, the parasite invades the brain and triggers progressive neurological deterioration, culminating in the comatose stage of sleeping sickness and death. In livestock, the chronic nagana form slowly debilitates animals, slashing their productivity before eventually killing them.
How does Trypanosoma brucei differ from other protozoan parasites?
Whereas most protozoan pathogens hide inside red blood cells or tissue cells, T. brucei is strictly extracellular, spending its entire parasitic phase suspended in plasma and bodily fluids. That open, cell-free lifestyle is precisely what forces it to develop its elaborate antigenic-variation machinery to survive relentless immune attacks.
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