title: Experimental transmission of Corynebacterium pseudotuberculosis biovar equi in horses by house flies.
abstract: BACKGROUND
  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.
authors.affiliation: Department of Clinical Sciences, Auburn University, Auburn, AL.
authors.forename: M
authors.initials: M
authors.lastname: Barba
authors.forename: A J
authors.initials: AJ
authors.lastname: Stewart
authors.forename: T
authors.initials: T
authors.lastname: Passler
authors.forename: A A
authors.initials: AA
authors.lastname: Wooldridge
authors.forename: E
authors.initials: E
authors.lastname: van Santen
authors.forename: M F
authors.initials: MF
authors.lastname: Chamorro
authors.forename: R C
authors.initials: RC
authors.lastname: Cattley
authors.forename: T
authors.initials: T
authors.lastname: Hathcock
authors.forename: J A
authors.initials: JA
authors.lastname: Hogsette
authors.forename: X P
authors.initials: XP
authors.lastname: Hu
mesh_terms: D000818:Animals; D003354:Corynebacterium Infections / Q000382:microbiology / Q000635:transmission / Q000662:veterinary*; D016925:Corynebacterium pseudotuberculosis / Q000502:physiology*; D004175:Diptera / Q000382:microbiology*; D006734:Horse Diseases / Q000382:microbiology / Q000635:transmission*; D006736:Horses; D007303:Insect Vectors / Q000382:microbiology*; D017192:Skin Diseases, Bacterial / Q000382:microbiology / Q000635:transmission / Q000662:veterinary
keywords: Equine; Musca domestica; Pigeon fever; Vector
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