Assam situated in the North East India has recently been known to be endemic for Theileria orientalis besides long known Babesia bigemina and Anaplasma marginale. This communication reports occurrence of T. orientalis in a herd of Holstein-Friesian lactating cattle and concomitant infection with Trypanosoma evansi in 2 of them. Herd investigation revealed the animals apparently healthy except 3 which manifested anorexia, depression, drop in milk yield, high fever, tachypnoea and blood values (haemoglobin and packed cell volume) at or below the lower limit of reference range. Giemsa stained blood smear examination revealed presence of crescent or rod shaped piroplasms with trailing cytoplasm of T. orientalis in all animals and additional presence of T. evansi in 2 out of 3 clinically ill cattle in subsequent blood examination. All the animals received antitheilerial treatment with Buparvaquone (Zubion) @ 2.5 mg/kg body weight in single I/M dose while T. evansi positive animals received single dose of Isometamidium hydrochloride (Nyzom) @ 0.3 mg/kg b. wt I/M. Parasite specific treatment along with intravenous Dextrose saline, oral vitamin and mineral supplementation could result resolution of clinical symptoms, progressive improvement in health, appetite and milk yield of animals within a month after treatment.
