This is Presentation of Trypanosoma cruzi(American disease) caused by parasites.

1. Trypanosoma cruzi
BP231507
Swetha. S
1st M.Sc Microbiology

2. History and Distribution
• T. cruzi is the causative organism of Chagas disease or South American
trypanosomiasis.
• It is a zoonotic disease and is limited to South and Central America.
• Carlos Chagas, investigating malaria in Brazil in 1909, accidentally found
this trypanosome in the intestine of a triatomine bug and then in the
blood of a monkey bitten by the infected bugs.
• Chagas named the parasite T. cruzi after his mentor Oswaldo Cruz and the
disease was named as Chagas disease in his honor.

3. Habitat
• In humans, T. cruzi exists in both amastigote and trypomastigote forms:
* Amastigotes are the intracellular parasites. They are found in
muscular tissue, nervous tissue and reticuloendothelial system.
* Trypomastigotes are found in the peripheral blood.
• In reduviid bugs, epimastigote forms are found in the midgut and
metacyclic trypomastigote forms are present in hindgut and feces.

4. Morphology
• Amastigote : Amastigotes are oval bodies measuring 2-4 micrometer in
diameter having a nucleus and kinetoplast.
• Trypomastigote : Trypomastigote are nonmultiplying forms found in the
peripheral blood of man and other mammalian hosts.
• Epimastigote form : Epimastigote forms are found in the insect vector,
the reduviid bug and in culture also. Epimastigote divide by binary fission
in hindgut of the vector.

5. Life cycle of Trypanosoma cruzi

6. Mode of Transmission
• Transmission of infection to man and other reservoir hosts takes place
when mucus membranes, conjunctiva, or wound on the surface of the skin
is contaminated by feces of the bug containing metacyclic
trypomastigotes.
• T. cruzi can also be transmitted by the blood transfusion, organ
transplantation and vertical transmission, from mother to fetus or very
rarely by ingestion of contaminated food or drink.

7. Pathogenicity and Clinical features
• The incubation period of T. cruzi in man is 1-2 weeks. The disease manifests in
acute and chronic form.
* Acute chagas disease : Acute phase occurs soon after infection and may last
for 1-4 months. It is seen often in children under 2 years of age. The patient may die
of acute myocarditis and meningoencephalitis.
* Chronic chagas disease : The chronic form is found in adults and older
children and becomes apparent years or even decades after the initial infection.
* Congenital infection : Congenital transmission is possible in both acute and
chronic phase of the disease causing myocardial and neurological damage in the
fetus.

8. Laboratory Diagnosis
• Diagnosis is done by demonstration of T. cruzi in blood or tissues or by
serology.
* Microscopy
* Culture
* Animal inoculation
* Xenodiagnosis
* Histopathology

9. • Serology
* Antigen detection
* Antibody detection
* Intradermal test
• Molecular diagnosis
* Polymerase chain reaction is available that detects specific
primers, which have been developed against T. cruzi kinetoplastic or nuclear
DNA. The disadvantage of the test is that it is not commercially available.
• Other tests
* Electrocardiography(ECG) and Chest X-ray
* Endoscopy

10. Treatment
• No effective specific treatment is available for treating Chagas disease. Nifurtimox
and benznidazole have been used with some success in both acute and chronic
Chagas disease.
• These drugs kill only the extracellular trypanosomes but not the intracellular forms.
• Dose : Nifurtimox – 8 -10 mg/kg for adults and 15mg/kg for children. The drug
should be given orally in four divided dose each day for 90-120 days.
Benznidazole – 5-10 mg/day orally for 60 days.
• Prophylaxis : Application of insecticide to control the vector bug. Personal
protection using insect repellent and mosquito net.