Trichinella larvae in Chile is difficult to study in wild fauna because most carnivore vertebrates are protected by law [31], either due to conservationist concerns or because they support pest control. Only invasive animals can be hunted for assessing the Trichinella infection and the larvae isolation. Given that, few studies have assessed the presence of Trichinella infection in native carnivores in Chile: Alvarez et al. [26] included two güiñas and 24 lesser grisons, in addition to other mammals, and González-Acuña et al. [27] included two güiñas, with negative results in both cases. Other studies in Argentina included another wild cat (Leopardus geoffroyi) and the lesser grison with negative results [32, 33]. Thus, this is the first record of Trichinella larvae in a native mustelid in South America, and the first record of T. spiralis in the güiña, with the güiña being the second South American felid host for this parasitic species. Previously, other mustelids have been reported to host Trichinella elsewhere, as Neovison vison (American mink) hosting T. spiralis, T. britovi and T. pseudospiralis in Poland [34], as well as Meles meles (European badger) hosting T. britovi in Romania [35]. Similarly, other felids have been reported harboring Trichinella in Chile, as Puma concolor harboring T. spiralis [25], and elsewhere, as Puma concolor harboring T. patagoniensis in Argentina [20], Puma concolor coryi harboring T. spiralis and T. pseudospiralis in USA [36], Puma concolor cougar harboring Trichinella nativa, Trichinella pseudospiralis, Trichinella murrelli and Trichinella T6 [37], Lynx rufus harboring T. britovi and Felis silvestris harboring T. britovi and T. spiralis [38].
The güiña is one of the smallest felids in the world, with a restricted distribution in Chile and Argentina between 33º and 48º of latitude S [39]. This felid consumes micromammals preys as primary items [40, 41], in such a way that this prey, especially rodents, can be the source of infection. However, rodents have been recognized as hosts of T. spiralis mainly in the domestic environment in Chile [23, 42]. This record is in accordance with the fact that guiñas have been frequently infected by micro-organisms spilled from free-range domestic animals [43, 44]; and, although T. spiralis is not an important pathogen for the health of non-human animals, its presence in the güiña highlights the need of surveyance of pathogens in the rural-sylvatic interphase.
The lesser grison is a Neotropical mustelid that inhabit an area from southern Peru, Uruguay and Paraguay to southern Chile and Argentina, encompassing several environments [45], and is a generalist predator, including rodents as an important part of its diet [46, 47]. Given that, this species most likely can be infected in the domestic environment; however, a further identification of the Trichinella species that the lesser grison harbors allows to better understand the source of infection, given that not all Trichinella species identified in South America have been reported in the domestic cycle. For instance, T. patagoniensis has been reported only in cougars [20, 48].
To the best of our knowledge, there is no report of the guiña as prey of larger predators while B. magellanicus (Magellanic horned owl) is the sole predator reported for the lesser grison [45]. Regarding that, T. pseudospiralis, also zoonotic, is the only species of the genus reported to infect birds. This species has not been reported in Chile with the record of a single pig from Argentina being the sole report in South America [18]. Thus, it is most unlikely that this owl could be a way for Trichinella to be transmitted from the grison to another species. Hence, whether guiña and lesser grison participate in the reservoir or constitute dead-end hosts is unknown, and the most likely way for Trichinella larvae to be transmitted from these hosts seems to be their consumption by carrion-consuming mammal. Therefore, further studies are necessary to test this hypothesis. On the other hand, human trichinellosis after the direct consumption of a free-range mammal has been also reported worldwide [7, 8]; however, neither guiñas nor grisons are typical prey for hunters to eat, nor is their hunting permitted by law in Chile [31].
It is noteworthy that the two host species herein reported correspond to the mammal species with the larger sample size, which suggests that larger samples in the other mammals could output new hosts for Trichinella. The contrasting lack of finding of Alvarez et al. [26] could be due to a real absence of larvae in their samples, as well as to the parasitological technique, trichinoscopy, which is of lower sensitivity [49].