The life cycle of Trypanosoma cruzi in the human host. In this video, we see the life cycle of Trypanosoma cruzi in the human host. The Trypanosome life cycle begins with the triatomine insect, which is infected with T. cruzi, biting a human host. Following the ingestion of blood, the metacyclic trypomastigotes are released with the feces from the insect near the area of the bite.
Note that this form has great motility. Observe that the parasite enters the host through the bite site when the host scratches the site. or when the parasite moves to a region covered by mucosa.
The parasite reaches the mammalian bloodstream and subsequently invades different cell types that it encounters, such as macrophages, muscle cells, epithelial cells, and neurons. In this example, the attachment of the trypomastigote form of the parasite to the macrophage surface is observed. The process of internalization via phagocytosis begins with the formation of pseudopods. During and after the internalization of the parasite, the parasitophorous vacuole assembles.
Host cell lysosomes migrate toward the internalization region and fuse with the parasitophorous vacuole. The lysosomal content is released in the vacuole. However, the parasite is not affected. In the vacuole, the trypomastigote transforms into an amastigote.
This transformation is accompanied by the disruption of the parasitophorous vacuole membrane. The amastigotes are released into the cytoplasm of the host cell and divide multiple times. Observe how many amastigotes are accumulating through the division process. They can occupy the entire cytoplasm of the host cell. Following division, the amastigotes transform into trypomastigotes, which show intense and constant movement that culminates with their bursting out of the cell.
The trypomastigotes reach the extracellular space and, subsequently, the bloodstream. The parasites will now infect new cells.