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28 Cards in this Set

  • Front
  • Back
Name the 3 common trypanosomes.
1. African trypanosomes
2. American trypanosomes
3. Leishmaniasis
Name 3 features common to all trypanosomes.
1. Asexual reproduction
2. Single flagella and kinetoplast
3. Can live in water
Name the 4 life cycle stages of trypanosomes. Where is each found - in the mammal host or vector?
1. Amastigote - mammal host
2. Promastigote - insect vector
3. Epimastigote - insect vector
4. Trypomastigote - mammal host
Describe the flagella of the amastigote and trypomastigote.
*amastigote is aflagellar
*trypomastigote has a flagella that stretches the length of the organism
Where in the parasite is the kinetoplast located? How much of the organism's total DNA is contained here?
What is unique about the DNA contained in the kinetoplast?
The RNA transcribed from it does not code for protein.
How many minicircles of DNA are contained in the kinetoplast? Describe its function.
*code for guide RNA that binds DNA produced by maxicircles and inserts uracil residues
How many maxicircles of DNA are contained in the kinetoplast? Describe their function.
*code for mRNA that is edited and then yields proteins
What is the vector for African trypanosomiasis? What feature of its reproduction makes it difficult to control with insecticide?
*tsetse fly
*eggs hatch in uterus and fed with milk glands
*larva are deposited in soil and develop into pupae
What are two differences between the East African and West African forms of African trypanosomiasis?
1. West has a human reservoir; East has an animal reservoir
2. West associated with chronic disease; East associated with acute disease
Describe the 3 stages of disease in African trypanosomiasis.
1. Primary: swollen lymph nodes
2. Secondary: fever, wasting, systemic infection
3. Advanced: CNS penetration with lethargy, mental status changes, coma, death
What is the periodicity of African trypanosomiasis? What causes this?
*1-2 weeks
*complete antigenic turnover of parasites with renewed immune response
How many new cases of African trypanosomiasis are seen each year?
What is the causative agent of Chaga's disease?
T. cruzi
What cells does the amastigote form of T. cruzi inhabit? How is it able to live here?
*macrophages (or muscle cells)
*escape the phagolysosome to reproduce in the cytoplasm
What forms does T. cruzi adopt in human and animal reservoirs? In its vector?
*Reservoir: amastigote, trypomastigote
*Vector: epimastigote, metacyclic, trypomastigote
What is the vector of T. cruzi? How is the parasite transferred from its vector to a human host?
*Reduviid beetle (a triatome)
*the beetle takes a blood meal and defecates at the site of penetration
Describe the acute form of Chaga's disease. What are the symptoms of the chronic form?
*acute: facial and eyelid swelling, parasitemia, fever
*chronic: occurs years after acquisition, chronic cardiomyopathy, megacolon, mega esophagus
How is Chaga's disease currently diagnosed?
Serology and immunological tests.
What is the vector of Leishmaniasis?
Sand fly
What form does the Leishmaniasis parasite take in the human host? In in the insect vector?
*host: amastigote
*vector: promastigote
Describe the pathogenesis of the leishmaniasis parasite in the human host.
The parasite is taken up by macrophages and remain in the phagolysosome to reproduce until the cell eventually ruptures.
How many people are infected by the cutaneous/mucocutaneous form of leishmaniasis each year? What are the symptoms of this form? Where is this form endemic?
*1-1.5 million/year
*painless ulcer that heals into a hypopigmented scar
*South America and the Middle East
How many people contract the visceral form of Leishmaniasis each year? What are the symptoms of this form?
*spread through the RES causes splenomegaly, hepatomegaly, and bone marrow depression with associated cytopenia
What are the two forms of visceral leishmaniasis? Which has an animal reservoir?
*endemic: animal reservoir
*epidemic: no animal reservoir
Name two patient populations that are particularly susceptible to severe disease with leishmaniasis infection.
*malnourished peds
Name the two strains of leishmaniasis. Is each strain specific for one disease form vs. the other?
*dermatrophic and viscerotrophic
*each can cause either disease form
Name 3 means of diagnosing leishmaniasis.
1. culture
2. serology
3. skin test