First record of Gongylonema nepalensis in domestic and wild ruminants in Europe.

The gullet worm, Gongylonema pulchrum, is cosmopolitan in distribution, infecting a variety of mammals including domestic and wild ruminants. Gongylonema nepalensis recently collected from the esophageal epithelium of water buffaloes in Nepal was separated from G. pulchrum based on its distinctly shorter left spicule relative to body length and unique nucleotide sequences of the ribosomal RNA gene (rDNA) and the mitochondrial cytochrome c oxidase subunit 1 gene (cox-1). During meat inspections at four abattoirs on Sardinia Island, Italy, 25 Gongylonema worms were collected from one each individual of cattle (n=8), sheep (n=7), goats (n=4), and mouflon (Ovis aries musimon; n=6), and characterized morphologically and genetically. Intriguingly, all of the collected worms from these ruminants were G. nepalensis, exhibiting comparable body lengths to G. pulchrum in cattle from other regions but with significantly shorter left spicules like G. nepalensis (less than 20.9% of the entire body length in contrast to 21.8-65.6%, the reported proportion of G. pulchrum). Furthermore, the rDNA nucleotide sequences of these worms from different ruminant species on Sardinia Island were almost identical to each other and to Nepalese G. nepalensis isolates. With the exception of one worm from a sheep (displaying a single nucleotide substitution), the 369-bp cox-1 nucleotide sequences of all the Sardinian G. nepalensis isolates from the different host sources were absolutely identical, forming a clade with Nepalese G. nepalensis isolates and not G. pulchrum isolates. The present study reveals that G. nepalensis is not a local parasite in the Indian subcontinent (Nepal), but instead has a certain geographical distribution in Europe and takes several ruminant species as a definitive host.