Trypanosoma cruzi (2) Flashcards
What are the hosts?
Dogs
Cats
Humans
Wild Animals
- Armadillos - Raccoons - Opossums - Rats - Guinea pigs - Monkeys - Reservoir Hosts
Vectors required
What is the common name?
Chaga’s disease
How do you identify?
Trypomastigotes in blood smear
- Elongated
- Spindle/leaf shaped
- 20 micro m long
- Nucleus near middle of length
- Posterior end pointed
- Single flagellum near posterior end and close to kinetoplast (small
granule of extranuclear DNA)
- Extends along body in edge of undulating membrane and
terminates in free flagellum of anterior tip
Explain life cycle
Infected triatomine insect vector takes blood meal and releases trypomastigotes in its feces near site of bite wound
Trypomastigotes enter host
- Wound or through intact mucosal membranes
- Other routes in humans
- Transmission also takes place when dogs drink water with infected
bugs
Trypomastigotes invade cells - differentiate into Intracellular
amastigotes
Amastigotes multiply by binary fission
- Intracellular amastigotes transform into trypomastigotes, then
burst out of the cell and enter bloodstream
Trypomastigote infects cells
Transform into Intracellular amastigotes in new infection sites
“Kissing” bug infected by feeding on blood containing circulating parasites
In insect infective metacyclic Trypomastigotes form in hindgut
Clinical manifestations can result from this infective cycle
Epimastigotes in midgut of triatomine bug
Multiply in midgut
What are the sites of infection?
Muscle
Blood
Describe the pathogenesis
Amastigotes cause pathology in heart muscles
3 stages of disease
- Acute - Latent - Chronic
Highly pathogenic - acute and chronic cardiac disease
Pale mucus membranes
Lethargy
Ascites
Hepatomegaly - enlargement of liver
Splenomegaly - enlargement of spleen
Tachyarrhythmia - irregularity of normal heart rhythm
Acute disease characterized by lymphadenopathy - disease of lymph
nodes
Neurology signs
Kittens/Puppies most susceptible
How do you diagnose?
Blood smear demonstrates trypomastigotes
Serological tests
Xenodiagnosis - requires several weeks
- Uninfected bugs allowed to feed on individual - Hindguts examined later for presence of trypanosomes
How do you treat and prevent?
No satisfactory treatment known
Dogs may be treated with pour on insecticides
- Repel/kill bugs
Epidemiology depends on 3 factors
- Distribution of vectors - Virulence of parasite - Response of host
Transmission reduced by considering sources of infection
Areas where reservoir hosts reported
- Elevate awareness
What is important about Trypanosoma cruzi?
It is ZOONOTIC