Trypanosoma cruzi (2)

Question 1

What are the hosts?

Answer 1

Dogs

Cats

Humans

Wild Animals

 - Armadillos
 - Raccoons
 - Opossums
 - Rats
 - Guinea pigs
 - Monkeys
 - Reservoir Hosts

Vectors required

Question 2

What is the common name?

Answer 2

Chaga’s disease

Question 3

How do you identify?

Answer 3

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

Question 4

Explain life cycle

Answer 4

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

Question 5

What are the sites of infection?

Answer 5

Muscle

Blood

Question 6

Describe the pathogenesis

Answer 6

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

Question 7

How do you diagnose?

Answer 7

Blood smear demonstrates trypomastigotes

Serological tests

Xenodiagnosis - requires several weeks

 - Uninfected bugs allowed to feed on individual 
 - Hindguts examined later for presence of trypanosomes

Question 8

How do you treat and prevent?

Answer 8

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

Question 9

What is important about Trypanosoma cruzi?

Answer 9

It is ZOONOTIC