Genetic Variation Within and Between G1 and G3 Genotypes of <i>Echinococcus granulosus sensu stricto</i> from Chile Revealed by Partial DNA Sequencing of <i>rrnS</i> Gene Marker

<b><i>Background:</i></b> Cystic echinococcosis (CE) caused by the parasite <i>Echinococcus granulosus sensu lato</i> is one of the most important zoonoses worldwide, causing a great impact on human and animal health. Despite its impact, control programs have not been able to eradicate the parasite; in part, because its transmission cycles, its phylogeny, and the host-parasite relationships are still not well known. In order to deepen knowledge about <i>Echinococcus</i> spp. populations in the endemic areas of southern Chile, the present study was carried out. <b><i>Materials and Methods:</i></b> Ten isolates of CE cysts were analyzed, mostly from cattle from southern Chile. A segment of the gene that codes for ribosomal RNA of the minor subunit of the ribosome (<i>rrnS</i> marker) was amplified by PCR using total DNA from this parasite as a sample. Then, they were sequenced, analyzed by molecular phylogeny, and their haplotype network was studied. <b><i>Results:</i></b> It was demonstrated that the <i>rrnS</i> marker allows the unambiguous identification of genotypes G1 and G3. Interestingly, it was found that some Chilean parasite isolates of genotype G1 could ancestrally originate from Spain; different to the majority of these isolates that would come from Turkey or Iran. However, further studies are required to confirm this hypothesis. In addition, an animal was detected that had been infected on at least two occasions by parasites with different haplotypes. <b><i>Conclusion:</i></b> The present results support the usefulness of the <i>rrnS</i> marker to identify the G1 and G3 genotypes, allowing a simple and low-cost tool for large-scale studies. More information is provided on the population structure of the populations of <i>E. granulosus sensu stricto</i> from Chile and the usefulness of distinguishing between different haplotypes is verified; increasing the resolution of the information that can be very useful to providing more information on the phylogenetic relationships and molecular history of this important parasite.