An unexpected case of a Japanese wild boar (Sus scrofa leucomystax) infected with the giant thorny-headed worm (Macracanthorhynchus hirudinaceus) on the mainland of Japan (Honshu)

Abstract

The giant thorny-headed worm Macracanthorhynchus hirudinaceus is a zoonotic acanthocephalan species with a worldwide distribution. Its natural definitive hosts are primarily pigs and wild boars (Sus scrofa), and scarabaeid beetles serve as the intermediate host. To date, there has only been one record of this acanthocephalan in Japan: a Ryukyu wild boar (Sus scrofa riukiuanus) hunted in 1973 on Amami Island, faraway from the Japanese mainland. The present study reports the second case of this acanthocephalan in Japan: a Japanese wild boar (Sus scrofa leucomystax) hunted in May 2017 in Yamaguchi Prefecture, the westernmost part of the Japanese mainland (Honshu). More than a dozen acanthocephalans (123 to 233 mm in length and 5 to 6 mm in width) were found with their proboscides inserted deeply into the intestinal wall, forming grossly visible nodules on the external surface. Isolated worms underwent a molecular genetic characterization of the ribosomal RNA gene (rDNA) and mitochondrial cytochrome c oxidase subunit 1 gene (cox-1). Long rDNA nucleotide sequences (5870 to 5890 bp) spanning the beginning of the 18S rDNA through to the 28S rDNA, including the internal transcribed spacer regions, and 1384-bp cox-1 nucleotide sequences were obtained. In the future, in conjunction with the accumulation of molecular genetic data of multiple M. hirudinaceus isolates from different endemic localities abroad, our data may help to postulate the origin or present transmission status of this extremely rarely encountered acanthocephalan in Japan.

A Neglected Parasite: Macracanthorhynchus hirudinaceus, First Report in Feral Pigs in a Natural Park of Sicily (Southern Italy)

“…Macracanthorhynchus hirudinaceus eggs are very resistant in the environment and remain infectious for up to 3 years, tolerating both drought and below-zero temperatures ( 32 ). Currently, the reduced number of reports of human cases is probably a consequence of the low endemicity of the parasite due to the changes in pig farming and improved health education ( 33 ).…”

New morphological and molecular perspectives aboutMacracanthorhynchus hirudinaceus(Acanthocephala: Oligacanthorhynchidae) from wild boar,Sus scrofaLinn., in Ukraine

“…The amplified region corresponded to the approximate middle region of the small subunit ribosomal ribonucleic acid gene, which is ∼1800 nt in length (see García-Varela et al, 2021). Comparative sequence analysis revealed that this sequence differs by 1 nt (0.21%), consisting in a nucleotide substitution, from the three M. hirudinaceus sequences obtained by Kamimura et al (2018) from specimens infecting wild boar in Japan (LC350000-2), the only 18S rDNA sequences for this species currently available in GenBank. The other species of this genus for which genetic data are available, M. ingens, is represented by two 18S rDNA sequences in GenBank.…”

First molecular description of Macracanthorhynchus hirudinaceus in wild boars from Italy with pathomorphological and epidemiological insights

“…The European sequences were more similar to each other compared to the Japanese sequence displaying heterogeneity among the different geographical populations. Only two reports of M. hirudinaceus occurrence are reported in Japan and are yet to be established whether this species is accidentally introduced or has endemic status (Kamimura et al 2018). But the clustering of Japanese isolate separately from the European population shows that independent factors are operative at different geographical areas affecting the genetic structure of the species.…”

“…DNA from six collected worms was extracted using G-spin™ Total DNA Extraction kit (iNtRON Biotechnology, Korea) according to the manufacturer's instructions. PCR amplification of the mitochondrial cytochrome c oxidase subunit 1 gene (cox1) was performed using one set of primers, Acanth_Cox1-F1 (5′-TTT GGA GGG GTT TGA TGG GT-3′) and Acanth_Cox1-R4 (5′-CCC CAG ACA TTC TTC TCT CCA-3′), and the same conditions previously described (Kamimura et al 2018). PCR products were purified using Nucleospin Gel and PCR Clean Up (Macherey-Nagel GmbH & Co. KG, Düren, Germany) and sent to an external sequencing service (Eurofins Genomics, Ebersberg, Germany).…”

“…PCR products were purified using Nucleospin Gel and PCR Clean Up (Macherey-Nagel GmbH & Co. KG, Düren, Germany) and sent to an external sequencing service (Eurofins Genomics, Ebersberg, Germany). The sequences were obtained using primers Acanth_cox1-F4 (5′-TTG GGT ATT TGG GCA TGG TG-3′) and Acanth_cox1-R2 (5′-CAC CAT GCC CAA ATA CCC AA-3′) employed exclusively for sequencing (Kamimura et al 2018) of the partial cox1 gene and compared with the reference sequences for M. hirudinaceus (FR856886, Weber et al 2013;LC350021, Kamimura et al 2018) available on the NCBI database using BLAST algorithm (https:// blast. ncbi.…”