*Evaluation of Molecular Variability of Isolates of* Trypanosoma cruzi *in the State… DOI: http://dx.doi.org/10.5772/intechopen.104498*

analyzed for the variability of the intergenic region of the Mini-Exon gene showed a profile of bands with 150 bp characteristic of zymodeme III and bands with a lower intensity with ~ 250pb, also indicating a profile for TcII. The PCR amplification of the ribosomal RNA gene (24Sα) using the primers D71 and D72 resulted in fragments 125pb showing a characteristic line TcII. In order to verify possible hybrid characters among the strains analyzed was done with PCR using specific primers tmuts30 and tmuts41 based on analysis of polymorphisms in the MSH2 gene with the digestion of the amplification product of a region of this gene with the restriction enzyme *Hha*I (*Haemophilus haemolyticus*) which resulted in fragments of 173pb, 207 pb and 294pb for each isolate, which also indicated a pattern characteristic for strain Tc II, showing then there is no hybrids between these isolates.

According to a protocol for determining DTU proposed by D´Ávila *et al*. [30] through the polymorphism analysis of the mitochondrial cytochrome oxidase subunit 2 (COII) gene, amplification of the D7 divergent domain of the 24Sα rRNA gene and amplification of the spliced leader intergenic region (SL-IRac) was possible to found two DTU circulating in the studied area.

Our results corroborate the hypothesis that isolated from *T. cruzi* infection may be a product of a mixture of populations of parasites as the vector into the wild environment can feed on various mammalian hosts. This complex was demonstrated by Fernandes *et al.* [18] in a study in the state of Rio de Janeiro showed that the association of two strains (TcI and TcII) with different wild hosts.

Evidence indicates that different populations of *T. cruzi* may circulate in nature by independent cycles of transmission and that these may, under certain conditions, if overlap. In these cases of overlapping cycles, one must admit that possibly different populations, which remained isolated, start to interact in the same vector and/ or host. But while there is that possibility, little is known about these mechanisms between these different populations when they come into sympatry. The remarkable capacity of the parasite to infect several species implies adaptation of the parasite to live in various microhabitats, including the different segments of the intestinal tract of the insect [53, 54], nucleated mammalian cells including macrophages [55], blood and also the discharge of the scent glands some marsupials [56, 57]. Some of these are apparently microhabitats hostile to the development of the parasite [58].

Experimental studies have shown that mixed infection with *T. cruzi* can have a major impact on the biological properties of the parasite in the host, emphasizing the possible occurrence of natural mixed infections in humans and its consequences on the biological aspects of Chagas disease [2].

Our isolates showed indeed a correlation TcIV (formerly Z3) with TcII, indicating that these locality samples associating both the sylvatic cycle, as the domestic cycle, respectively, confirming the complexity of the sylvatic cycle of the disease. These results suggest that in this area might occur studied cycle *T. cruzi* epidemiological characteristics proposed by Zingales *et al*. [12], where both strains circulate in the wild habitat.

As TcV and TcVI, TcII has rarely been recorded in wild cycles and their natural niches are not well defined. Recent studies have demonstrated that TcII strain was isolated from opossums and primates in the wild forest, which led to the suggestion that primates could be the primary mammalian hosts of original TcII [59].

TcIV is relatively the more poorly understood group. It is the type responsible for the cause of Chagas disease in Venezuela [48] and was also responsible for the first record of an outbreak of acute cases simultaneously orally transmitted Chagas disease in the suburb of Canudos, State of Belém do Pará/Brazil [40].

Understanding the distribution and phylogeography of TcIV is complicated by the fact that several genotyping methods can not distinguish this strain from others, particularly TcIII.

It is important to emphasize that, TcIV and TcI is known to be endemic, in, North America, and were associated with raccoons in this region [60, 61]. Moreover, there is evidence that TcIV in North America is quite different from TcIV in South America [49, 62], and the presence of identical sequences of mitochondrial DNA in North America strains TcIV and TcI lineages suggests that genetic exchange has contributed to the diversity of strains seen in North America ([51]; Yeo *et al*, unpublished data).

The existence of mixed populations isolated from the *T. vitticeps* may reflect the pressure that these insects are suffering due to human action, prompting them to move into different ecological niches, increasing the possibility of contracting the infection of different hosts [63].

Genotyping demonstrates that the strains have a history that makes biological sense with widely current ecological structure, although the details are not yet well elucidated, but still require further research. The study of the genetic diversity of *T. cruzi* is of great importance for the control of Chagas disease. As seen, the application of molecular methods has shown that this parasite is possibly a body, but a fascinating complex heterogeneous, which will inevitably have different phenotypes. Molecular epidemiology can reveal the different types of transmission cycles and this is very important to develop strategies for vector control and understand their limitations.

*Evaluation of Molecular Variability of Isolates of* Trypanosoma cruzi *in the State… DOI: http://dx.doi.org/10.5772/intechopen.104498*
