The prevalence of Cowdria ruminantium in free-living adult Amblyomma hebraeum collected at a communal grazing area and in 2 wildlife reserves in South Africa

In order to detect the prevalence of Cowdria ruminantium in the vector tick, Amblyomma hebraeum, free-living, unfed adult ticks were collected with the aid of pheromone/CO2 traps. Ticks were collected at the Rietgat communal grazing area, as well as in the southwestern Kruger National Park and in the Songimvelo Game Reserve, all located in heartwater-endemic areas of South Africa. The presence of C. ruminantium in these ticks was determined by polymerase chain reaction (PCR) analysis. Ticks from the Rietgat communal grazing area were assayed in 2 batches and 4.7% of the one and 11.3% of the other were positive for infection, while 5.7% of the ticks collected in the Kruger National Park and 25% in the Songimvelo Game Reserve were positive. These results support the contention that a vector-wildlife cycle of transmission of C. ruminantium, the cause of heartwater in domestic ruminants, can be maintained in the absence of the latter animals.