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Journal of veterinary internal medicine2015; 29(2); 636-643; doi: 10.1111/jvim.12545

Experimental transmission of Corynebacterium pseudotuberculosis biovar equi in horses by house flies.

Abstract: The route of Corynebacterium pseudotuberculosis infection in horses remains undetermined, but transmission by insects is suspected. Objective: To investigate house flies (Musca domestica L.) as vectors of C. pseudotuberculosis transmission in horses. Methods: Eight healthy, adult ponies. Methods: Randomized, controlled, blinded prospective study. Ten wounds were created in the pectoral region where cages for flies were attached. Three ponies were directly inoculated with C. pseudotuberculosis. Four ponies were exposed for 24 hours to 20 hours C. pseudotuberculosis-inoculated flies. One negative control pony was exposed to noninoculated flies. Ponies were examined daily for swelling, heat, pain, and drainage at the inoculation site. Blood was collected weekly for CBC and biochemical analysis, and twice weekly for synergistic hemolysis inhibition titers. Results: Clinical signs of local infection and positive cultures were observed in 7/7 exposed ponies and were absent in the negative control. In exposed ponies, peak serologic titers (1:512 to 1:2,048) were obtained between days 17 and 21. Seroconversion was not observed in the negative control. Neutrophil counts were higher in the positive and fly-exposed groups than in the negative control (P = .002 and P = .005) on day 3 postinoculation. Serum amyloid A concentrations were higher in the positive control than in the negative control and fly-exposed ponies on days 3 (P < .0001) and 7 (P = .0004 and P = .0001). No differences were detected for other biochemical variables. Conclusions: House flies can serve as mechanical vectors of C. pseudotuberculosis and can transmit the bacterium to ponies.
Publication Date: 2015-03-31 PubMed ID: 25818218PubMed Central: PMC4895518DOI: 10.1111/jvim.12545Google Scholar: Lookup
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  • Journal Article
  • Randomized Controlled Trial
  • Research Support
  • Non-U.S. Gov't

Summary

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The research paper investigates whether house flies can transmit Corynebacterium pseudotuberculosis, a bacteria causing infection, to horses. It concludes that indeed, house flies can serve as mechanical vectors for the bacterium and can transmit it to ponies.

Introduction and Objectives

  • The primary aim of this study was to determine if house flies (Musca domestica L.) can act as vectors for the transmission of Corynebacterium pseudotuberculosis in horses.

Methodology

  • The researchers conducted a randomized, controlled, blinded prospective study involving eight healthy adult ponies.
  • Ten wounds were created on each pony’s pectoral region where cages for flies were attached. Three ponies were directly inoculated with C. pseudotuberculosis while four ponies were exposed to flies that had been inoculated with the bacterium for 24 hours. A negative control pony was exposed to non-inoculated flies.

Examinations and Analysis

  • The ponies were daily examined for signs of infection like swelling, heat, pain, and drainage at the inoculation site.
  • Blood samples were collected weekly for Complete Blood Count (CBC) and biochemical analysis, and twice weekly for synergistic hemolysis inhibition titers which is a test to detect antibodies.

Results

  • Local infection signs and positive cultures were observed in all the seven ponies exposed to the bacterium, while these were absent in the negative control.
  • Peak serologic titers, indicating an immune response, ranged from 1:512 to 1:2,048 and were noticed between the 17th and 21st days in the exposed ponies. The negative control did not show any seroconversion – a clear indication that an infection had taken place.
  • The neutrophil counts, which are a type of white blood cell that fights infection, were higher in the positive control and the fly-exposed group than in the negative control.
  • The positive control had a higher concentration of serum amyloid A, a biomarker for inflammation, than the negative control and the fly-exposed ponies, especially on the 3rd and 7th days after inoculation.

Conclusion

  • The results of this study demonstrate that house flies can act as mechanical vectors for C. pseudotuberculosis and transmit the bacterium to ponies, thereby causing infection.

Cite This Article

APA
Barba M, Stewart AJ, Passler T, Wooldridge AA, van Santen E, Chamorro MF, Cattley RC, Hathcock T, Hogsette JA, Hu XP. (2015). Experimental transmission of Corynebacterium pseudotuberculosis biovar equi in horses by house flies. J Vet Intern Med, 29(2), 636-643. https://doi.org/10.1111/jvim.12545

Publication

ISSN: 1939-1676
NlmUniqueID: 8708660
Country: United States
Language: English
Volume: 29
Issue: 2
Pages: 636-643

Researcher Affiliations

Barba, M
  • Department of Clinical Sciences, Auburn University, Auburn, AL.
Stewart, A J
    Passler, T
      Wooldridge, A A
        van Santen, E
          Chamorro, M F
            Cattley, R C
              Hathcock, T
                Hogsette, J A
                  Hu, X P

                    MeSH Terms

                    • Animals
                    • Corynebacterium Infections / microbiology
                    • Corynebacterium Infections / transmission
                    • Corynebacterium Infections / veterinary
                    • Corynebacterium pseudotuberculosis / physiology
                    • Diptera / microbiology
                    • Horse Diseases / microbiology
                    • Horse Diseases / transmission
                    • Horses
                    • Insect Vectors / microbiology
                    • Skin Diseases, Bacterial / microbiology
                    • Skin Diseases, Bacterial / transmission
                    • Skin Diseases, Bacterial / veterinary

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