Incidence of Ehrlichia bovis infection in Tamil Nadu*

Abstract

The incidence of Ehrlichia bovis among bovines in Tamil Nadu was studied by blood smear examination. The organism could be detected in 16.59% of the cattle and 14.29% of the buffaloes that attended the large animal clinic of Madras Veterinary College. In the samples received from the field, E. bovis is was found in 6.34% of cattle and 6.45% of buffaloes. While young ones and adults were found to be equally susceptible, the incidence was higher among Holstein-Friesian cross calves. The organism was more frequently found in conjunction with other haemoparasites, especially Theileria annulata. The highest incidence was recorded between October and February. The ticks commonly encountered on E. bovis infected animals were Boophilus sp., Haemaphysalis sp. and Hyalomma sp. Lymphnode aspirate smears were the ideal clinical specimen for diagnosing E. bovis infection.