Molecular detection of filarial nematode parasites in Japanese black bears (Ursus thibetanus japonicus) from Iwate Prefecture, Japan

J Vet Med Sci. 2021 Feb 25;83(2):208-213. doi: 10.1292/jvms.20-0466. Epub 2020 Dec 14.


This study aimed to detect filarial parasites in blood samples of Japanese black bears (Ursus thibetanus japonicus) collected from Iwate Prefecture, Japan. Positive amplicons were obtained from 26 out of 30 samples by nested PCR targeting 18S ribosomal RNA gene and first internal transcribed spacer regions. DNA sequences of Mansonella sp. close to M. ozzardi and Dirofilaria sp. were detected for eight and 11 positive amplicons, respectively. Co-infection was detected for the remaining seven amplicons. Dirofilaria sp. was identified as D. ursi by further genetic analysis of 5S ribosomal RNA gene sequence. The results of this study will contribute to further investigations of Japanese black bears for monitoring their risk as a reservoir of possible zoonotic filarial parasites.

Keywords: Japanese black bear; PCR; filaria; phylogenetic analysis.

MeSH terms

  • Animals
  • Female
  • Filariasis / diagnosis
  • Filariasis / epidemiology
  • Filariasis / parasitology
  • Filariasis / veterinary*
  • Filarioidea / classification
  • Filarioidea / genetics
  • Filarioidea / isolation & purification*
  • Japan / epidemiology
  • Male
  • RNA, Ribosomal, 18S / genetics
  • Ursidae / parasitology*


  • RNA, Ribosomal, 18S