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 c
attle 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
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 h
ighest incidence was recorded between October and February. The ticks commo
nly encountered on E. bovis infected animals were Boophilus sp., Haemaphysa
lis sp. and Hyalomma sp. Lymphnode aspirate smears were the ideal clinical
specimen for diagnosing E. bovis infection.