Effect of treatment of chronic theileriosis with buparvaquone on milk yields.

Chronic, undulating Theileria annulata infection was diagnosed as the cause of severely depressed milk yields in a herd of 44 Friesian cows in Egypt. The herd was divided at random into two groups of 22; one group was injected intramuscularly with a single dose of the experimental antitheilerial drug, buparvaquone, while the other remained untreated. Over the subsequent seven weeks milk yield in the treated group increased to double that of the untreated group (P less than 0.05). Pyrexia was controlled within two days of injection of buparvaquone and piroplasm parasitaemia was eliminated in one week. It is suggested that treatment of dairy cattle chronically infected with T. annulata using buparvaquone may have the dual beneficial effect of reducing the pathogenic effects of theileriosis, thereby permitting restoration of an impaired immune system, thus increasing resistance to other infections. If a similar effect could be produced in Bos indicus cattle in T. annulata endemic areas, treatment of indigenous cattle with buparvaquone could be a useful alternative to the introduction of Bos taurus blood as a way of boosting milk production.