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Journal of wildlife diseases2006; 42(3); 518-526; doi: 10.7589/0090-3558-42.3.518

Equine piroplasmoses at the reintroduction site of the Przewalski’s horse (Equus ferus przewalskii) in Mongolia.

Abstract: Piroplasmosis has been identified as a possible cause of mortality in reintroduced Przewalski's horses (Equus ferus przewalskii) in the Dsungarian Gobi (Mongolia). A cross-sectional and a longitudinal study were conducted in a representative sample (n = 141) of the resident domestic horse population and in 23 Przewalski's horses to assess the prevalence of Theileria equi and Babesia caballi. Piroplasms were detected in blood by light microscopy in 6.7% (95% confidence interval [CI]: 3.6-12.2%) of the domestic horse samples. Antibody prevalence was 88.6% (95% CI: 82.4-92.9%) for T. equi and 75.2% (95% CI: 67.4-81.6%) for B. caballi. Antibody prevalence did not change over time, but antibody prevalence for both piroplasms were significantly lower in animals less than 1 yr of age. For both piroplasms, the prevalence of presumably maternal antibodies (falling titers) in foals was 100%. Only one of 16 foals seroconverted against T. equi during the study period, despite that piroplasms were found in two other individuals. The incidence density (ID) of T. equi in foals was therefore 0.0012 seroconversions per horse day (95% CI: 0.00029-0.0057). In contrast, yearlings had an ID of 0.0080 (95% CI: 0.0049-0.010) for T. equi and 0.0064 (95% CI: 0.0036-0.0093) for B. caballi, and in seven individuals piroplasms were detected. The seroprevalence of both piroplasms rose from 20% in spring to 100% in autumn. Comparison of domestic and Przewalski's horses resulted in a standardized prevalence ratio (SPR) of 0.98 (95% CI: 0.80-1.24, not significant) for B. caballi; in contrast, the prevalence of T. equi in Przewalski's horses was significantly lower than expected (SPR = 0.51, 95% CI: 0.50-0.64).
Publication Date: 2006-11-10 PubMed ID: 17092882DOI: 10.7589/0090-3558-42.3.518Google Scholar: Lookup
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  • Journal Article
  • Research Support
  • Non-U.S. Gov't

Summary

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The research explores the prevalence of piroplasmosis, a disease potentially fatal to Przewalski’s horses, in Mongolia. It identifies two prevalent strains of the disease in both domestic and Przewalski’s horses, with young foals showing significantly lower antibody prevalence.

Research Overview

  • The research was conducted with the main objective of investigating the prevalence of piroplasmosis, specifically the strains Theileria equi and Babesia caballi, amongst a sample involving domestic horse population and Przewalski’s horses.
  • The study was triggered by the hypothesis that piroplasmosis could be a primary cause of Przewalski’s horse mortality in Dsungarian Gobi, Mongolia, where these horses have been reintroduced.

Methodology and Findings

  • Both cross-sectional and longitudinal studies were carried out on a sample size of 141 domestic horses and 23 Przewalski’s individuals.
  • The prevalence of piroplasm, the parasites causing the disease, was detected in the horses’ blood using light microscopy. The prevalence was 6.7% in domestic horse samples.
  • Among all horse samples, 88.6% featured antibodies for Theileria equi, and 75.2% for Babesia caballi; These figures suggest high exposure to the disease.
  • However, the study found that the antibody prevalence did not change over time, but was significantly lower in horses less than a year old. All foals demonstrated apparent maternal antibodies with falling titers.

Comparative Analysis and Conclusions

  • Despite the high exposure to piroplasms, only one foal seroconverted against T. equi during the study period, suggesting a low incidence density
  • In contrast, yearlings had a higher incidence density for T. equi and B. caballi.
  • The seroprevalence of piroplasms increased with the change of seasons, from 20% in spring to 100% in autumn.
  • Upon comparing domestic and Przewalski’s horses, the study found a Standardized Prevalence Ratio (SPR) of 0.98 for B. caballi, indicating almost equal prevalence among the two horse types.
  • However, for T. equi, the prevalence in Przewalski’s horses was significantly lower than expected (SPR = 0.51).

Cite This Article

APA
Rüegg SR, Torgerson PR, Doherr MG, Deplazes P, Böse R, Robert N, Walzer C. (2006). Equine piroplasmoses at the reintroduction site of the Przewalski’s horse (Equus ferus przewalskii) in Mongolia. J Wildl Dis, 42(3), 518-526. https://doi.org/10.7589/0090-3558-42.3.518

Publication

ISSN: 0090-3558
NlmUniqueID: 0244160
Country: United States
Language: English
Volume: 42
Issue: 3
Pages: 518-526

Researcher Affiliations

Rüegg, Simon R
  • Institute of Parasitology, University of Zürich, Winterthurstrasse 266A, CH-8057 Zürich, Switzerland.
Torgerson, Paul R
    Doherr, Marcus G
      Deplazes, Peter
        Böse, Reinhard
          Robert, Nadia
            Walzer, Christian

              MeSH Terms

              • Age Factors
              • Animals
              • Antibodies, Protozoan / blood
              • Babesia / immunology
              • Babesia / isolation & purification
              • Babesiosis / epidemiology
              • Babesiosis / veterinary
              • Cross-Sectional Studies
              • Female
              • Horse Diseases / epidemiology
              • Horses
              • Longitudinal Studies
              • Male
              • Mongolia / epidemiology
              • Seroepidemiologic Studies
              • Theileria / immunology
              • Theileria / isolation & purification
              • Theileriasis / epidemiology

              Citations

              This article has been cited 4 times.
              1. Tang Y, Liu G, Zhao S, Li K, Zhang D, Liu S, Hu D. Major Histocompatibility Complex (MHC) Diversity of the Reintroduction Populations of Endangered Przewalski's Horse. Genes (Basel) 2022 May 23;13(5).
                doi: 10.3390/genes13050928pubmed: 35627313google scholar: lookup
              2. Narankhajid M, Yeruult C, Gurbadam A, Battsetseg J, Aberle SW, Bayartogtokh B, Joachim A, Duscher GG. Some aspects on tick species in Mongolia and their potential role in the transmission of equine piroplasms, Anaplasma phagocytophilum and Borrelia burgdorferi L. Parasitol Res 2018 Nov;117(11):3557-3566.
                doi: 10.1007/s00436-018-6053-xpubmed: 30178195google scholar: lookup
              3. Michel AO, Mathis A, Ryser-Degiorgis MP. Babesia spp. in European wild ruminant species: parasite diversity and risk factors for infection. Vet Res 2014 Jun 13;45(1):65.
                doi: 10.1186/1297-9716-45-65pubmed: 24925474google scholar: lookup
              4. Jaffer O, Abdishakur F, Hakimuddin F, Riya A, Wernery U, Schuster RK. A comparative study of serological tests and PCR for the diagnosis of equine piroplasmosis. Parasitol Res 2010 Feb;106(3):709-13.
                doi: 10.1007/s00436-009-1669-5pubmed: 19894063google scholar: lookup