Cowdria ruminantium infection in ticks in the Kruger National Park
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Veterinary Record;145(11): 304-307
Permanent link to this item: http://hdl.handle.net/10568/29920
Adult Amblyomma hebraeum ticks, the principle vector of heartwater (cowdriosis) of domestic ruminants in southern 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 percent (95 percent confidence interval 0.71 to 4.0 percent). A DNA proble analysis, which is less sensitive than PCR, detected infection in three of the five PCR positive ticks. The remaning 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. r uminantium can be maintained independently of domestic ruminants.