User Contributed Dictionary
- Protozoan parasites which are transmitted by biting insects and infect the blood of humans and other vertebrates.
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Extensive Definition
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
trypanosomiasis
(African Sleeping
Sickness and South American Chagas
Disease); these are caused by species of Trypanosoma.
Leishmaniasis
is a trypanosomal disease caused by species of Leishmania.
A variety of different forms appear in the
life-cycles of trypanosomes, distinguished mainly by the position
of the flagellum: All trypanosomes have at least amastigote and
promastigote stages. Trypanosoma appears in all five forms, with
the trypanosomal stage occurring in the vertebrate host.
Trypanosoma brucei sub-species have two forms in the bloodstream of
a vertebrate host, the rapidly dividing long-slender form and the
non-dividing short stumpy form. The short stumpy parasites are
adapted for uptake into the tsetse fly vector, and are
non-proliferative in comparison with the slender forms.
Unique to Trypansoma brucei is the expression of
a variable surface glycoprotein (VSG) coat on the cell surface,
which undergoes constant variation in order to evade the humoral
immune system and host antibodies. It is thought that recombination
from a repertoire of more than 1000 VSG genes is responsible for
the vast diversity of the parasite, and its effectiveness in immune
evasion.
trypanosome in French: Trypanosome
trypanosome in Spanish: Trypanosomatida
trypanosome in Japanese:
トリパノソーマ科