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Cowdria ruminantium infection in ticks in the Kruger National Park
  1. T. F. Peter, BSc, PhD1,
  2. N. R. Bryson, BVSc, BSc,MRCVS2,
  3. B. D. Perry, BVM&S,DTVM, MSc, DVM&S,FRCVS3,
  4. C. J. O'Callagan, DVM,MSc, PhD, MRCVS4,
  5. G. F. Medley, BSc, PhD4,
  6. G. E. Smith, BSc1,
  7. G. Mlambo, BSc1,
  8. I. G. Horak, DVSc, PhD5,
  9. M. J. Burridge, BVM&S,MPVM, PhD6 and
  10. S. M. Mahan, BVM, MSc,PhD1
  1. 1 University of Florida/USAID/SADC Heartwater Research Project, PO Box CY 551, Causeway, Harare, Zimbabwe
  2. 2 Department of Infectous Diseases and Public Health, Faculty of Veterinary Science, Medical University of South Africa, 0204, Republic of South Africa
  3. 3 International Livestock Research Institute, Nairobi, Kenya
  4. 4 Department of Biological Sciences, University of Warwick, Coventry CV4 7AL
  5. 5 Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, 0110, Republic of South Africa
  6. 6 Department of Pathobiology, College of Veterinary Medicine, University of Florida, Gainesville, Florida 32611-0880, USA


Adult Amblyomma hebraeum ticks, the principle vector of heartwater (cowdriosis) of domestic ruminants in southem Africa, were collected in pheromone traps placed in Kruger National Park, an exclusively wildlife sanctuary in South Africa. These ticks transmitted Cowdria ruminantium, the rickettsial agent causing heartwater, to a susceptible goat, resulting in acute, fatal disease. C ruminantium was isolated in bovine endothelial cell culture from the plasma of this animal during the febrile stage of the disease and transmitted to susceptible goats, causing fatal heartwater. The prevalence of C ruminantium infection in 292 ticks was determined by polymerase chain reaction (PCR) analysis to be 1.7 per cent (95 per cent confidence interval 0.71 to 4.0 per cent). A DNA probe analysis, which is less sensitive than KCR, detected infection in three of the five PCRpositive ticks. The remaining infections were below the detection limit of the DNA probe, which is approximately 70,000 organisms. This is the first evidence that a vector-wildlife cycle of transmission of C ruminantium can be maintained independently of domestic ruminants.

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