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18 Cards in this Set
- Front
- Back
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What are the two important species of trypanosomes?
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Trypanosoma brucei and cruzi
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What trypanosome causes African sleeping sickness?
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T. brucei
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Describe the morphology of trypanosomes
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They have a flagellum, a kinetoplast, a special variable surface glycoprotein coat, and an undulating membrane
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What is a kinetoplast?
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A filamentous body that lies in a mitochondrion in the body of the parasite
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What is the major vector for trypanosoma brucei?
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The tse-tse fly which is commonly found in central Africa
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What are the economical implications of T. brucei and tse tse fly infestation?
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T. brucei infects cattle, and the tse tse fly makes it impossible to raise cattle
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Describe the life cycle of T. brucei
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The tse tse fly ingests the trypomastigotes, where they reproduce in the gut of the fly; the trypomastigotes migrate to the salivary glands and transforms into metacyclic trypomastigotes; the fly bites an animal and injects the metacylic trypomastigotes into the host blood, which reproduce asexually and cause disease
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Describe the importance of the loss of the variable surface glycoprotein of T. brucei
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The organism makes a new coat every 5-7days, allowing for continued infection and evasion of the antibodies produced against the previous glycoprotein coat
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What is the winterbottom sign?
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Glandular enlargement due to infection with T. brucei
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Describe the clinical manifestations of African sleeping sickness
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It is a systemic illness characterized by fever, weakness, arthritis, rash and edema with eventual invasion of the CNS and cardiovascular systems
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Describe how the trypanosome surface glycoprotein can be shed
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Each organism has 15 million VSG molecules on its surface, and each protein is loosely attached; an enzyme cleaves the ethanolamine linkage of the glycoprotein
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Where must a variable surface glycoprotein gene be located in the genome of trypanosomes to be expressed?
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VSGs must be located in a telomeric site in order to be expressed
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What is the disease caused by T. Cruzi, and what is the major vector?
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T. Cruzi causes Chagas disease, with the Reduviid bug as the major transmitting vector
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Describe the pathogenesis of the T. cruzi transmission
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When the reduviid bug bites the potential host and takes a blood meal, it defecates the tryptomastigotes of T. cruzi onto the skin and the host scratches the bite, inoculating the parasite into the wound
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What forms of T. cruzi are seen in the blood and what forms are seen in the tissue?
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The typomastigote is seen in the blood and the amastigote intracellulary infects tissue (such as cardiac)
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Describe the pathogenesis of a T. cruzi infection
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The parasites disseminate through the bloodstream and form pseudocysts in the tissue; they secrete toxins that cause denervation
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What is Romana's sign?
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Red, swollen pus-filled sores on the eye seen in T. cruzi infection
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Describe the clinical manifestations of Chagas disease
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Anemia, dilated cardiomyopathy, chagomas, secondary megacolon due to denervation
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