Cowdria ruminantium identified in Amblyomma gemma using a DNA probe pCS20

Abstract

Amblyomma gemma ticks were collected from wild animals on a 20,000 acre game ranch in a heartwater endemic area in Kenya, close to Nairobi. A. variegatum is the main vector of heartwater in Kenya. E.A. LEWIS, 1947, in a one sentence report has implicated A. gemma to be a vector of heartwater without giving any details. Adult A. gemma were collected from giraffe Giraffa camelopardalis, hartebeest Alcephalus busephalus , Eland Taurotragus oryx and ostrich Struthio camelus during cropping exercises. The unengorged ticks were fed on 3 susceptible Dorper sheep which were monitored daily for the clinical symptoms of heartwater. All the ticks, including those that were fed on sheep were dissected and the guts probed for the presence of Cowdria ruminantium using a cloned DNA probe, the pCS20. None ofthe sheep on which the ticks were fed showed heartwater symptoms up to 60 days from the attachment of the ticks. The DNA probe identified Cowdria ruminantium in the ticks collected from eland and giraffe.