Chabaudstrongylus ninhae (Trichostrongylidae: Cooperiinae) and Oesophagostomum muntiacum (Chabertiidae: Oesophagostominae) in feral alien Reeves's muntjacs on Izu-Oshima Island, Tokyo, Japan.

The naturalization of alien Reeves's muntjacs (Muntiacus reevesi) on Izu-Oshima Island, Tokyo, Japan, has proceeded intensively over the last five decades. To clarify whether the gastrointestinal helminths of these animals were brought from their original endemic area or were newly acquired in Japan, 32 Reeves's muntjacs trapped on the island were parasitologically examined. In addition to Gongylonema pulchrum in the oesophagus (34.4% prevalence), Chabaudstrongylus ninhae (Drózdz, 1967) (Trichostrongylidae: Cooperiinae) and Oesophagostomum muntiacum Jian, 1989 (Chabertiidae: Oesophagostominae) were prevalent in the small (28.1%) and large (46.9%) intestines, respectively. For the first time, these trichostrongylid or chabertiid worms were genetically characterized based on partial nucleotide sequences of the nuclear ribosomal RNA gene (rDNA) and mitochondrial DNA cytochrome c oxidase subunit 1 gene (cox-1), and the phylogenetic relationships with other members of their family were explored. Since these two intestinal nematode species are inherent in muntjacs, this study demonstrates a new distribution of exotic helminth species in Japan in accordance with the naturalization of alien mammalian hosts. The molecular genetic data collected here could assist the taxonomic assessment of morphological variants in different Muntiacus spp. and/or of different geographical origins. Furthermore, our data may help to define the phylogenetic relationships among such isolates.

Gongylonema infection of wild mammals in Japan and Sardinia (Italy).

The gullet worms, classical Gongylonema pulchrum and newly differentiated Gongylonema nepalensis, are prevalent in various mammals in Japan and Sardinia, Italy, respectively. The former species is cosmopolitan in distribution, dwelling in the mucosa of the upper digestive tract of a variety of domestic and wild mammals, and also humans. At present, the geographical distribution of G. nepalensis is known in Nepal and Sardinia, with the nematode having been recorded from the oesophagus of water buffaloes (Nepal), cattle, sheep, goats and wild mouflon (Sardinia). To clarify their natural transmission cycles among domestic and wild mammals, the present study analysed the ribosomal RNA gene (rDNA) and mitochondrial cytochrome c oxidase subunit 1 gene (cox1) of worms of various origins: G. pulchrum worms from sika deer, wild boars, Japanese macaques, and feral alien Reeves's muntjacs in Japan, and G. nepalensis worms from a red fox and a wild boar in Sardinia. Although the internal transcribed spacer (ITS) regions of rDNA and partial cox1 nucleotide sequences of G. pulchrum from native wild mammals in Japan were distinct from those of the worms in cattle, the worms from feral alien Reeves's muntjacs showed the cattle-type ITS genotype and cox1 cattle-I and II haplotypes. The rDNA and cox1 nucleotide sequences of G. nepalensis from a red fox in Sardinia were almost identical to those of the worms from domestic and wild ruminants on the island. The ecological interaction between domestic and wild mammals and their susceptibility to different Gongylonema spp. must be considered when trying to elucidate this spirurid's transmission dynamics in nature.

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.

Genetic variation of Gongylonema pulchrum from wild animals and cattle in Japan based on ribosomal RNA and mitochondrial cytochrome c oxidase subunit I genes.

The gullet worm (Gongylonema pulchrum) has been recorded from a variety of mammals worldwide, including monkeys and humans. Due to its wide host range, it has been suggested that the worm may be transmitted locally to any mammalian host by chance. To investigate this notion, the ribosomal RNA gene (rDNA), mainly regions of the internal transcribed spacers (ITS) 1 and 2, and a cytochrome c oxidase subunit I (COI) region of mitochondrial DNA of G. pulchrum were characterized using parasites from the following hosts located in Japan: cattle, sika deer, wild boars, Japanese macaques, a feral Reeves's muntjac and captive squirrel monkeys. The rDNA nucleotide sequences of G. pulchrum were generally well conserved regardless of their host origin. However, a few insertions/deletions of nucleotides along with a few base substitutions in the ITS1 and ITS2 regions were observed in G. pulchrum from sika deer, wild boars and Japanese macaques, and those differed from G. pulchrum in cattle, the feral Reeves's muntjac and captive squirrel monkeys. The COI sequences of G. pulchrum were further divided into multiple haplotypes and two groups of haplotypes, i.e. those from a majority of sika deer, wild boars and Japanese macaques and those from cattle and zoo animals, were clearly differentiated. Our findings indicate that domestic and sylvatic transmission cycles of the gullet worm are currently present, at least in Japan.