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Parasitology research2014; 113(12); 4485-4490; doi: 10.1007/s00436-014-4135-y

Parascaris univalens–a victim of large-scale misidentification?

Abstract: The equine ascarid parasite Parascaris equorum is well known as a ubiquitous parasite infecting foals. A sibling species, Parascaris univalens, was first described over 130 years ago, but very little attention has been given to its existence and possible implications for anthelmintic resistance, clinical disease, or host age spectrum. P. univalens only possesses one germ line chromosome pair as opposed to two for P. equorum, but the two species are otherwise considered morphologically identical. For the present study, live worms obtained from the University of Kentucky parasitology horse herd were dissected and identified using karyotyping techniques. With no exception, all specimens (n = 30) were identified to be P. univalens. Further, the karyotyping technique was adapted to ascarid eggs derived from fecal samples and carried out on samples collected from 25 Thoroughbred foals from three farms in Central Kentucky. P. equorum was not identified among these, whereas P. univalens was found in 17 samples, with the remaining being inconclusive. The mitochondrial genome was sequenced, assembled, and annotated from one male worm identified as P. univalens, and comparison with available sequence reads labeled as P. equorum revealed only 0.16% nucleotide differences. However, it is unlikely that the sequences available in public databases have been unequivocally identified to species level by karyotyping. Taken together, these data suggest that P. univalens is likely the main species now observed in equines and that perhaps the designation Parascaris spp. should be used unless cytological characterization has confirmed the species.
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Publication Date: 2014-09-18 PubMed ID: 25231078DOI: 10.1007/s00436-014-4135-yGoogle Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research paper investigates the horse ascarid parasite known as Parascaris univalens, which has been largely ignored despite its potential implications for anthelmintic resistance and clinical disease. The study finds evidence to suggest that P. univalens may be the main species currently infecting horses, questioning the typical identification of these parasites as Parascaris equorum.

Objective and Methodology

  • The purpose of this study was to examine Parascaris univalens, a parasite species previously not given much attention, but which could potentially have significant implications for both health care and pest control in the equine world.
  • To carry out the investigation, the research team took live worm samples from the University of Kentucky’s parasitology horse herd. They dissected and identified these samples using karyotyping techniques, which look at the genetic make-up of cells.
  • The researchers adapted these techniques to analyze ascarid eggs from fecal samples taken from 25 Thoroughbred foals at three farms in Central Kentucky, further extending their study population.

Main Findings

  • All worm specimens from the University of Kentucky (30 in total) were identified as Parascaris univalens, not the commonly assumed Parascaris equorum.
  • Of the 25 fecal samples analyzed, none identified the presence of P. equorum. Instead, P. univalens was found in 17 samples, with the rest being inconclusive.
  • A male worm identified as P. univalens was subjected to mitochondrial genome sequencing. The resulting assembly and annotation were compared with sequence reads labeled as P. equorum. The results showed only 0.16% nucleotide differences, casting doubt on the accuracy of existing genetic information labeled as P. equorum in public databases.

Significance and Implications

  • The findings suggest that P. univalens may be the main species now observed in equines, rather than the usually assumed P. equorum. This raises important implications for the naming and identification of such parasites.
  • The research team suggest that unless cytological characterization has confirmed the species, the designation Parascaris spp. (indicating an unspecified species within the Parascaris genus) should be used.
  • The study highlights the potential for large-scale misidentification of P. univalens as P. equorum, showing the importance of proper species identification in parasitic control and health care in equine populations.

Cite This Article

APA
Nielsen MK, Wang J, Davis R, Bellaw JL, Lyons ET, Lear TL, Goday C. (2014). Parascaris univalens–a victim of large-scale misidentification? Parasitol Res, 113(12), 4485-4490. https://doi.org/10.1007/s00436-014-4135-y

Publication

Parasitology research
ISSN: 1432-1955
NlmUniqueID: 8703571
Country: Germany
Language: English
Volume: 113
Issue: 12
Pages: 4485-4490

Researcher Affiliations

Nielsen, Martin K
  • M. H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA, martin.nielsen@uky.edu.
Wang, Jianbin
    Davis, Richard
      Bellaw, Jennifer L
        Lyons, Eugene T
          Lear, Teri L
            Goday, Clara

              MeSH Terms

              • Animals
              • Ascaridida Infections / parasitology
              • Ascaridida Infections / veterinary
              • Ascaridoidea / classification
              • Ascaridoidea / genetics
              • Feces / parasitology
              • Female
              • Gene Expression Profiling
              • Genome, Mitochondrial
              • Helminth Proteins / analysis
              • Helminth Proteins / genetics
              • Horse Diseases / parasitology
              • Horses
              • Karyotyping / veterinary
              • Kentucky
              • Male
              • Molecular Sequence Data
              • Reference Values

              Grant Funding

              • R01 AI049558 / NIAID NIH HHS

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