First finding of Trichinella pseudospiralis in the Neotropical region.

Prior to this study, only encapsulated species of Trichinella had been found in South America, i.e., T. spiralis and T. patagoniensis. Here we report the molecular identification of a non-encapsulated isolate of Trichinella from a domestic pig in Argentina. The multiplex PCR technique and the analysis of mitochondrial and nuclear DNA sequences revealed that it belongs to T. pseudospiralis, which parasitises birds and mammals from Australian, Nearctic, and Palaearctic regions. Interestingly, the isolate is closely related to the Palaearctic population. This is the first report of a non-encapsulated species of Trichinella from the Neotropical region.

Trichinella patagoniensis n. sp. (Nematoda), a new encapsulated species infecting carnivorous mammals in South America.

Until a few years ago, Trichinella spiralis was the only taxon of the genus Trichinella detected in both domestic and wild animals of South America. Recently, a new genotype, named Trichinella T12, was identified in cougars (Puma concolor) from Argentina, on the basis of molecular studies using mitochondrial and nuclear ribosomal markers. In the present study, cross-breeding experiments indicated that Trichinella T12 is reproductively isolated from all other encapsulated Trichinella spp. and suggested that it is biologically more similar to Trichinella britovi and Trichinella murrelli than to the other encapsulated species/genotypes. Biological assays revealed that the reproductive capacity index of Trichinella T12 was ~4 and >2000 times lower than those of T. spiralis in mice and rats, respectively. The reproductive capacity index of Trichinella T12 in domestic pigs ranged from 0.0 to 0.05. Larvae parasitising the muscles of carnivores were infective to mice after freezing at -5°C for 3 months, but they lost infectivity after freezing at -18°C for 1 week. The region within the rDNA, known as the expansion segment V, showed a unique sequence which differs from those of all other known Trichinella spp./genotypes. The biological, geographical and molecular data support the classification of the genotype Trichinella T12 as a new species widespread in the Neotropical region, for which we propose the name Trichinella patagoniensis n. sp.

Molecular evidence for a novel encapsulated genotype of Trichinella from Patagonia, Argentina.

At present, Trichinella spiralis is the only species of this genus reported from South America. Herein, we detail a molecular analysis of a new encapsulated isolate of muscle larvae of Trichinella, found in a mountain lion (Puma concolor) coming from the Patagonia, Argentina. We studied three DNA regions previously probed to be useful for the identification of all eleven recognized Trichinella genotypes: expansion segment 5 (ES5), cytochrome c-oxidase subunit I (COI) and 5S ribosomal DNA intergenic spacer region (5S ISR). BLAST searches with these DNA sequences showed that the mitochondrial and nuclear ribosomal regions most closely resemble other Trichinella sequences available in GenBank. However, they did not exactly match any of the eleven recognized genotypes. The phylogenetic analysis from COI and 5S ISR sequences showed that the mountain lion isolate is grouped with encapsulated members, in concordance with morphological data. Furthermore, this new isolate was located at the base of the encapsulated genotypes, signifying that it is an old genotype that could have emerged earliest in this group. These data strongly suggest that this isolate from the Patagonia represents the twelfth genotype (T12) described in the genus Trichinella. Nevertheless, further studies are necessary to adequately establish this isolate as a unique genotype.