**3.** *Trypanosoma cruzi* **life cycle**

*T. cruzi* goes through several developmental stages. Within the vector, it is possible to find epimastigotes and metacyclic trypomastigotes, while blood trypomastigotes and amastigotes are found in vertebrates [17]. The cycle starts when a triatomine acquires blood trypomastigotes by sucking blood from an infected mammal [2]. Inside the vector, in the medial posterior gut, trypomastigotes differentiate to epimastigotes and duplicate. Afterward, epimastigotes migrate to the rectum, where they differentiate to metacyclic trypomastigotes. During the bloodmeal, vectors defecate and expel metacyclic trypomastigotes in their droppings that infect the mammal through the site of the bite, fissures in the skin, or mucous membranes [3, 18]. Parasites invade macrophages and connective tissue cells close to the site of entry due to the action of surface glycoproteins involved in the anchoring/penetration process such as gp82, gp83, gp85, and Tc-85, as well as glycoinositolphospholipids (GIPLs) [19–23]. Once inside cells, parasites have the ability to escape from the phagolysosome because of the action of enzymes such as a trans-sialidase (TS) and a low pH-dependent pore-forming protein, which allow them to reach the cytosol, where metacyclic trypomastigotes differentiate to amastigotes, duplicate, and finally transform to blood trypomastigotes that lyse the cell [24, 25]. They have the ability to surpass host effector mechanisms due to the expression of surface molecules such as GP160 and calreticulin that allow them to evade the action of complement, and GPI-mucins, which act as an antigenic protective coat. This antigenic coat presents variations that partially explain the differences in virulence and immunomodulation among strains [24, 26]. Trypomastigotes disseminate via lymph and blood to other tissues being able to infect any nucleated cell, but with certain tropism to macrophages, muscle cells (cardiac, smooth, and skeletal), and nervous cells. The cycle is completed when another vector ingests infected blood [17].
