PROZESKY, L. & DUPLESSIS, J. L., 1987. Heartwater. The development and life cycle of Cowdria rumiNJntium in the vertebrate host, ticks and cultured endothelial cells. Oruferstepoort JourNJl of VeteriNJry Research 54, 193-196 (1987) Various aspects of the development and life cycle of Cowdria rumiNJntium are discussed. C. rumiNJntium is transmitted transstadially by certain Amblyomma species. Apparently organisms initially develop in the ~t epithelial cells of ticks and subsequent stages of C.

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... miNJntium invade and develop in the salivary gland acmi cells of the vector. Stages at which transmission to the final host are attained appear to be coordinated with the feeding cycle of the ticks and the vertebrate host is infected via salivary glands of the tick. In the vertebrate host, ticks and cultured endothelial cells, different morphological forms of C. rumiNJntium (electron-dense and reticulated forms) are found. Organisms enter cells through a process resembling phagocyto-sis and reticulated forms of the organisms appear to be the main vegetative stage. In the vertebrate host, organisms proliferate in vascular endothelial cells, neutrophils, macrophages and reticulo-endothelial cells.