Page 37 - Medical Parasitology_ A Textbook ( PDFDrive )

Trypanosoma cruzi 29

Prevention and Control

1. Early diagnosis and early treatment of cases
2. Control of tsetse fly population using insecticides
3. Minimize contact with tsetse flies

Trypanosoma cruzi

Distribution

It is limited to South and Central America and it causes Chagas’ disease, which is a
zoonotic disease.

Habitat

In human, trypomastigotes are in the blood and amastigotes are in tissue.

Morphology

In humans, Trypanosoma cruzi exists in 2 forms, amastigote and trypomastigote.
Amastigotes are intracellular, oval bodies measuring 2–4 μm in diameter having a
nucleus and kinetoplast (Fig. 5.3a). Morphologically, it resembles the amastigote of
Leishmania spp. Multiplication of the parasite occurs in this stage. This form is
found in muscles, nerve cells and reticulo endothelial systems. In reduviid bugs,
amastigotes are found in the midgut.
Trypomastigote is a non-multiplying form found in the peripheral blood of
human and other mammalian hosts. In stained blood smears, they are ‘C’ or ‘U’
shaped, having a free flagellum of about one third the length of the body and a big
kinetoplast (Fig. 5.3b). In reduviid bugs, metacyclic trypomastigotes are present in
hindgut and faeces.

a b

Fig. 5.3 Trypanosoma cruzi. (a) Amastigotes in heart muscle, (b) Trypomastigote in blood