Spirocerca lupi in the stomach of two Andean foxes (Lycalopex culpaeus) from Chile

Abstract

The genus Spirocerca includes nematodes that parasitize the stomach and the oesophagus of carnivores, chiefly canids. Herein, we provide new data about the morphological, histopathological, and molecular characterization of Spirocerca sp. in Andean foxes (Lycalopex culpaeus) in Chile. Intact immature worms, identified as Spirocerca sp., were recovered in the lumen of the stomach from two foxes. Histologically, worms morphologically consistent with spirurid nematodes were present within the wall of the stomach and surrounded by nodular areas of inflammation with central necrotic debris. Molecular analysis of the cox1 gene yielded 19 sequences and 5 nucleotide sequence types with 99.95 to 99.98% similarity, being shared between both foxes. Nucleotide similarity ranged from 93.1 (with genotype 2 of S. lupi and S. vulpis) to 95.8% (with genotype 1 of S. lupi), a higher similarity than noted from sequences of S. lupi from an Andean fox from Peru (91.0 to 93.3%). However, the Poisson Tree Processes for species delineation did not support the existence of a new species Spirocerca. Phylogenetic and nucleotide analyses suggest that these specimens belong to a new variant or genotype of S. lupi or to a cryptic species. Whether the presence of the worms in the stomach has to do with genotypic differences in parasites or host or some combination is uncertain. Spirocerca lupi has never been found in Chilean dogs and must be investigated.

Elucidating Spirocerca lupi spread in the Americas by using phylogenetic and phylogeographic analyses

“…Accordingly, a 0.14%, 8.06% and 6.48% variation in the 18S rDNA, ITS1 and cox1, respectively, were found between genotypes. However, the phylogenetic relationships of S. lupi in the Americas is not yet elucidated, and cox1 sequences from Andean foxes from Peru and Chile (Gomez-Puerta et al, 2018;Di Cataldo et al, 2023) confirmed the high genetic variability observed in geographical locations in the Americas. The present study analyzed cox1 and 18S rDNA gene fragments of specimens from Costa Rica, Mexico, and the United States and compared them with the specimens from the Old World.…”

“…This parasite is distributed in the tropics and subtropics of the world, and extensive reports from Israel (Aroch et al, 2015), Southeast Asia (Aroch et al, 2015;Hoa et al, 2021), Africa (Greeff et al, 2018), and different regions of Europe (Giannelli et al, 2014;Psader et al, 2017) have been published. In the Americas, S. lupi has been detected in Southern United States of America (USA) in coyotes (Canis latrans), gray foxes (Urocyon cinereoargenteus), red foxes (Vulpes vulpes) and bobcats (Lynx rufus) (Pence and Stone, 1978;Morrison and Gier, 1979), in domestic dogs from USA (Pence and Stone, 1978), Mexico (Rodrıǵuez-Vivas et al, 2019), Costa Rica (De Aguiar et al, 2021), andBrazil (Costa Santos et al, 2012), in maned wolves (Chrysocyon brachyurus) from Brazil (Blume et al, 2014), Andean foxes (Lycalopex culpaeus) from Peru (Gomez-Puerta et al, 2018) and Chile (Di Cataldo et al, 2023), dogs in Colombia (Santisteban-Arenas and Piedrahita, 2016), bush dogs (Speothos venaticus) in Argentina (Rinas et al, 2009), and dogs in Grenada (Chikweto et al, 2012). Most reports have been done with the observation of eggs in feces or post-mortem macroscopic observation of adult worms in lesions at necropsy, but molecular analyses have been implemented for species confirmation only is some of these reports (Gomez-Puerta et al, 2018).…”