The Life Cycle of Trypanosoma Cruzi

Trypanosoma cruzi is a flagellated, insect-transmitted protozoa, living in blood and tissues of infected mammalian hosts. The species is endemic to Central and South America and causes Chagas disease. The life cycle of T. cruzi involves multiple stages and life in a mammalian host and arthropod vector.

Epimastigote

The T. cruzi life cycle begins with an arthropod vector, typically reduviid bugs, which are also called "kissing bugs" because they commonly bite mammalian hosts in the facial area. T. cruzi lives in the vector's salivary gland, in a form called an epimastigote, with a free flagellum but only a partial membrane.

Trypomastigote

While in the salivary gland, the epimastigote transforms into a trypomastigote, with a free flagellum and a complete membrane. The trypomastigotes move to the blood, lymph and sometimes central nervous system of the arthropod vector, and they are excreted into the feces.

Transmission to Mammalian Host

The reduviid bugs inject trypomastigotes into mammalian hosts by biting the host, burrowing into the skin and defecating into the wound.

Amastigote

T. cruzi trypomastigotes colonize in mammalian host tissues and organs, losing their flagella and membranes. They encyst in the amastigote form, infecting cells, replicating by binary fission, destroying cells and releasing progeny.

Transmission to Arthropod Vector

Most progeny are in the amastigote form, but some are trypomastigotes, living in the blood and lymph of the mammalian host. The trypomastigotes infect a reduviid bug when the bug feeds on the host and then transform back into epimastigotes in the midgut of the reduviid bug, repeating the life cycle.

References

• Medical Microbiology; P.R. Murray et al.; 3rd ed.; 1998
• Centers for Disease Control and Prevention; Chagas Disease
• Virginia Commonwealth University: Virtual Parasite Project