Parasitology Exam 3: Hemoflagellates Flashcards
What are the 2 genera of hemoflagellates that infect humans?
Leishmania spp.
Trypanosoma spp.
Kinetoplast
A network of circular DNA inside a large mitochondrion found in hemoflagellates
What are the 4 morphological stages of hemoflagellates?
Amastigote
Promastigote
Epimastigote
Trypomastigote
**Not successive, no pattern, any form is capable of developing into another form
Describe amastigotes
Usually develop in vertebrate host cells
Ovoid, single prominent nucleus, very short flagellum projecting barely beyond the cell surface
Describe promastigotes
Occurs only in the insect vector
More elongated than amastigote
Long flagellum and 2 mitochondrial branches
Describe epimastigotes
Kinetoplast-basal body complex situated more anteriorly than in promastigotes, but remains anterior to the nucleus
Has an undulating membrane
Describe trypomastigotes
Polymorphic
Long and slender or stumpy
Undulating membrane is much larger and prominent
What is a hemoflagellate?
Flagellate protozoans found in the blood of humans
What are the causative organisms of African Trypanosomiasis? What is the vector?
Vector: Tsetse fly (Glossina spp.)
Trypanosoma brucei gambiense –> West African
Trypanosoma brucei rhodesiense (East African)
What are the natural reservoir hosts of Trypanosoma?
Game animals like bushbuck and cattle
What is unique about African Trypanosomes?
They can change the antigens on the membrane of their trypomastigote every 5-7 days, allowing them to evade host’s immune response
Sustained high IgM levels
What is the infective stage of Trypanosomiasis?
Injection of trypomastigotes by tsetse fly
What is the diagnostic stage of Trypanosomiasis?
Trypomastigotes in blood
What does T. brucei gambiense cause? What are the symptoms/pathogenesis?
West African Sleeping Sickness
Stage 1 - no CNS involvement
Stage 2 - organisms invade CNS, progressive meningoencephalitis
Lymphadenopathy, hepatomegaly and/or splenomegaly
Somnolence
State of drowsiness (symptoms of Sleeping Sickness, stage 2)
What does T. brucei rhodesiense cause? What are the symptoms/pathogenesis?
East African Sleeping Sickness
More rapid, fulminating disease
Myocarditis
Death before extensive CNS involvement
General morphology of African Trypomastigotes
Kinetoplast located at posterior end, stains red
Undulating membrane and flagellum arise from the kinetoplast
What is another name for American Trypanosomiasis?
Chaga’s Disease
What is the causative organism of American Trypanosomiasis/Chagas Disease?
Trypanosoma cruzi
What is the vector of Chagas disease?
Reduviid bug/kissing bug/triatomid bug
How is Chagas disease transmitted?
Reduviid bug bites you, poops, scratch the bite, and the feces gets into your tissue/bloodstream
Can also be transmitted via blood transfusion or organ transplantation
Describe the life cycle of Chagas Disease
- Trypomastigotes ingested by reduviid bug during blood meal
- Transform into epimastigotes
- More tryptomastigotes
- Bug defecates while biting human
- Human scratches bite
- Trypomastigotes travel in blood
- Amastigotes multiply in cell and released into blood with trypomastigotes
What are the vectors for African and for American trypanosomiasis?
African - Tsetse fly
American - Kissing bug
What is a specific feature of American trypomastigotes (chagas)
C or U shaped!!
Pathogenesis of Chagas disease
Acute Symptoms:
Myocarditis, death from myocardial insufficiency or cardiac arrest
Chronic symptoms:
Megacolon
Cardiac changes (enlargement of heart, conduction changes)
Routine method for diagnosis of Trypanosomiasis
Thick and thin blood films
What is Xenodiagnosis?
Used to detect light infections like chronic infections
Differentiate between T. cruzi and T. brucei trypomastigote morphology
T. cruzi is C or U shaped
What species cause Leishmaniasis?
L. donovani
L. braziliensis
What disease is 2nd in mortality and 4th in morbidity among all tropical diseases?
Leishmaniasis
What is the vector of Leishmaniasis?
Sandfly
What are the 2 distinct phases of Leishmaniasis life cycle and where are they seen?
Amastigote - seen in humans
Promastigote - seen in insects
What are the infective/diagnostic stages of Leishmaniasis?
Infective: Sandfly introduces PROMASTIGOTES into skin
Diagnostic: Detection of AMASTIGOTES in tissues
What is CL? MCL?
Cutaneous Leishmaniasis
Mucocutaneous Leishmaniasis
- First sign is a lesion at the bite site, secondary lesions develop
Similar presentations
What is VL?
Visceral Leishmaniasis, AKA Kala-azar
Enlarged liver and spleen, swollen lymph nodes
What is diffuse leishmaniasis?
Nodular disease that results in high parasitemia due to an inappropriate antibody response of the patient
What are the characteristics of severe VL (kala-azar)
Characteristic hypergammaglobulinemia of both IgG and IgM
