Trypanosomes Flashcards
What stain can ID trypanosomes ?
Wright-Giemsa
2 subspecies of African trypanosomiasis. Causes what disease ?
T. Brucei rhodesiense
Trypanosoma brucei gambiense
- African sleeping sickness
Species of American trypanosomiasis. Causes what disease ?
T. cruzi
- Chagas disease
Species of Trypanosomes that infects animals. Causes what disease ?
T. brucei brucei
- Nagana disease
T or F: subspecies of African trypanosomes can be morphologically differentiated
FALSE; subspecies of African trypanosomes ARE NOT morphologically differentiated
Are African trypanosomes flagellated ?
Yes, they are protozoan hemoflagelletes
Vector for African trypanosomes
Tsetse flies, belongs to Glossina genus
Where does sleeping sickness ONLY occur ?
In Sub-Saharan Africa
Two anatomical characteristics that distinguish Tse-tse flies
- Rested wings fold directly over another
- Long proboscis extends directly forward, attached by distinct bulb to bottom of head
Life cycle of African trypanosomes
Mammalian:
1. Tse-tse takes blood meal
2. Injected metacyclic from transforms into bloodstream trypomastigotes = multiple by binary fission in various body fluids (blood, lymph, spinal)
3. Detectable trypomastigotes in blood during acute phase
Tse-tse:
1. Tse-tse takes blood meal
2. Bloodstream trypomastigotes transform into procylic form in midgut
3. Leaves midgut and transform into epimastigotes
4. Epimastigotes multiply in salivary gland = transform into metacyclic form
Incubation period of T. brucei rhodesiense
5-20 days*
NOTE: 3-21 days (usually 5-14)
Describe pathogenesis of T. brucei
- Bite = proliferation of trypanosomes within chancre
- parasites invade lymph nodes; continue proliferation
- enters bloodstream from lymphatics; proliferation
- invade interstitial spaces = vessel impeermeability and mott cells - Invades brains = meningoencephalitis
- CNS infiltrated with plasma cells/ lymphs, mott cells
- CSF = increased pressure, total protein, mono, eos
NOTE: complex/ poorly understood
Self-protecting mechanism of African trypanosomes
- antigenic variation = trypomastigote changes surface glycoproteins on outer membrane = evade’s host immune response
- by the time host can respond, trypomastigote has already switched its coat
Differentiate disease states between T. brucei rhodesiense (East) and T. brucei gambiense (West)
T. b rhodesiense:
- animals
- early CNS disease
- acute; rapid
- sore at tse-tse bite
- enlarged lymph nodes
- death within months
T. b gambiense:
- humans
- late CNS disease
- chronic; slow
- low parasitemia
- death within years
Diagnosis of T. brucei rhodensiense vs T. brucei gambiense
T. brucei rhodensiense:
- blood smear (HIGH %parasitemia)
- LYMPH NODE fluid
- chancre biopsy/ aspirate
- CSF
T. brucei gambiense:
- blood smear (low %parasitemia)
- LYMPH NODE fluid
- chancre biopsy/ aspirate
- CSF
-CATT
-ELISA
-**IFA*
CATT - card agglutination test for trypanosomes
Blood and CSF specimens should be examined __ therapy and __ months post-therapy
Blood and CSF specimens should be examined DURING therapy and 1-2 months post-therapy
T or F: African trypanosomes do not have intracellular forms and multiple as trypomastigotes that circulate the blood/ intracellular spaces
TRUE; African trypanosomes do not have intracellular forms and multiple as trypomastigotes that circulate the blood/ intracellular spaces
Diagnosis of African Trypanosomiasis
- history (travel)
- physical exam (chancre)
- laboratory (blood smear, CSF lumbar puncture staining,
Diagnosis of African Trypanosomiasis
- history (travel)
- physical exam (chancre)
- ## laboratory (blood smear, CSF lumbar puncture staining,
When should %parasitemia be measured ? Why ?
Blood during febrile period; HIGHEST %PARASITEMIA
Describe structural stages of Trypanosomes
Vector (trypomastigote/ epimastigote):
- anterior (sharp); flagella
- posterior (blunt); kinetoplast
- undulating membrane reduced over stages
Human (promastigote/ amastigote):
- anterior (flagella AND kinetoplast) and posterior
- no undulating membrane
- becomes more circular (intracellular), loses flagella
Transmission of T. Cruzi
- Triatomine insects/ “kissing bugs” (vector)
- ingestion of triatomine poop
- pregnant women to child
- blood transfusion/ organ transplant
Structure Stages of American Trypanosomes
Vector:
1. Trypomastigotes
- (anterior) flagella runs entire length from posterior
- undulating membrane
- kinetoplast (posterior)
2. Epimastigotes
- loses undulating membrane
3. Promastigotes
- kinetoplast AND flagella (anterior)
Human:
4. Amastigote (intracellular, human stage)
- round
- no flagella or cilia
WIP Life cycle of Trypanosoma cruzi
Triatomine insect:
1. Takes blood meal
