**5. Discussion**

Many studies have been performed for the characterization of isolates of *Trypanosoma cruzi* obtained from human cases, animal reservoirs and triatomines mainly in Latin America, highlighting the heterogeneity of this species [31–39].

In previous studies using isoenzyme analysis, samples of zymodemes were grouped into three and were related to different isozyme groups found with the epidemiological profile of the isolates. Thus, zymodemes I (Z1) and III (Z3) are related to the sylvatic cycle of the parasite and zymodeme II (Z2) to the domestic cycle [7, 40]. Through molecular biology techniques [10, 12, 16, 20, 41–46] was able to evidence a clear dimorphism between the isolates of *T.cruzi*, leading to pooling of samples into two major phylogenetic lineages: Tc I and TcII. Related phylogenetic groups with TcI and TcII zymodemes: TcI was related to the Z1 and TcII be related to the Z2. However, the position of Z3 in relation to TcI and TcII phylogenetic groups remains controversial and is constantly debated. Some authors consider that Z3 is phylogenetically closer than TcI/TcII [19, 47, 48], while other authors consider the opposite [49–51]. However, other authors have included Z3 in an intermediate position between Z1 and Z2 [52].

In 2009 the scientific community was divided into six groups (Tc I-VI) and each group was termed DTU ("discrete typing unit"), which can be identified by the markers molecular or common immunological [27]. In the 70s and 80s, a large number of "group" was identified, and 90 years in 2000, only two major groups, and currently six groups.

In this study, samples of *T. cruzi* isolated from *Triatoma vitticeps* from the municipality of Santa Maria Magadalena, State of Rio de Janeiro, were analyzed by several molecular markers, showing a mixed population. The 14 isolates
