Microbiology
Summary
Trypanosoma brucei is a species of parasites with three main members: Trypanosoma b. gambiense, Trypanosoma b. rhodesiense, and Trypanosoma b. brucei, the latter of which does not cause disease in humans, but is studied due to its similarity to the two infectious subspecies. These parasites all share a similar morphology with long bodies and a single flagellum. A key characteristic of these parasites is their ability to alter their surface glycoproteins, allowing them to evade the host's immune system. The infective form of these protozoans, known as the metacyclic trypomastigote, is transmitted into the human host through the bite of a tsetse fly.
T. b. gambiense and T. b. rhodesiense infection can lead to a severe condition known as sleeping sickness.T. b. gambiense is found in Western to Central Africa and causes a slowly progressing, chronic infection, while T. b. rhodesiense is found in the Eastern and Southeastern African savannahs and results in a quicker, more severe manifestation of the disease. This illness has two stages of infection: the hemolymphatic phase, which affects the blood and lymphatics, followed by the neurological or meningoencephalitic phase. The CSF can be analyzed to determine the stage of sleeping sickness. In the 1st stage, there are few WBCs and no detectable organisms, whereas the 2nd stage shows an elevated WBC count with the presence of organisms. The treatment options for sleeping sickness, including pentamidine, suramin, nifurtimox-eflornithine combination therapy (NECT), and melarsoprol, are determined by the specific parasitic variant and illness stage.
Lesson Outline
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FAQs
Trypanosoma brucei is a species of parasitic protozoan that causes human African trypanosomiasis, also known as sleeping sickness. This parasite is primarily transmitted to humans through the bite of an infected tsetse fly. There are two subspecies of Trypanosoma brucei that cause different forms of sleeping sickness: T. b. gambiense and T. b. rhodesiense.
Trypanosomiasis is a group of diseases caused by protozoan parasites of the genus Trypanosoma. African trypanosomiasis, also known as sleeping sickness, is specifically caused by the T. b. gambiense and T. b. rhodesiense strains of Trypanosoma brucei. The disease is typically characterized by periods of fever, headaches, joint pains, and itching in its early stages. In the advanced stage, it affects the central nervous system, leading to changes in behavior, confusion, and poor coordination, amongst other symptoms. If left untreated, it can lead to death.
Trypanosoma b. gambiense and Trypanosoma b. rhodesiense are subspecies of T. brucei that cause African trypanosomiasis. T. b. gambiense causes a slow-progressing form of the disease that can last several years, whereas T. b. rhodesiense causes a more acute and rapidly progressing form of the disease.
The tsetse fly is the main carrier of Trypanosoma brucei. When it bites an infected animal, it takes in the parasite. Inside the fly, the parasite changes form and multiplies. It then moves to the fly's salivary glands. When the fly bites again, it transfers the infectious form of the parasite to a new host, continuing the cycle.
In Trypanosoma brucei, surface glycoproteins play crucial roles in enabling the parasite to avoid the host's immune system. They tend to coat the parasite's surface and constantly change their structure, creating a phenomenon known as antigenic variation. This allows the parasite to persist in the host body while avoiding immune detection, thereby contributing to the chronic nature of the infections caused by this parasite.
