Delayed Toxicity of Certain Trypanocidal Drugs in East African Zebu Cattle

Abstract

IN a series of experiments during the past eighteen months, the trypanocidal drug 2 : 7-diamino-9-phenyl-10-methylphenanthridinium bromide (‘Phenanthridinium 1553’, ‘Dimidium bromide’) has been shown to produce a specific toxicity in native cattle at Kabete, Kenya. A syndrome developed between thirty-five and fifty days after inoculation, characterized by loss in weight and condition, a positive direct van den Bergh reaction with clinically observable jaundice in some cases and elevated serum alkaline phosphatase. A periportal fatty infiltration of the liver was found in biopsy and necropsy material. The symptoms of ‘photosensitization’ already described by other workers and which, although of such spasmodic occurrence, are nevertheless of economic importance in East Africa, have developed in only four of more than a hundred experimental animals inoculated and kept at Kabete. The liver toxicity has been observed regularly at dosage-levels of 2 and 3 mgm./kgm. body-weight given subcutaneously, intravenously or intramuscularly. Doses of 1 mgm./kgm., which is the usual therapeutic level, were occasionally toxic. Larger doses subcutaneously or repeated smaller dosage intravenously produced the same syndrome or loss in weight from thirty days after inoculation, death occurring about fifty days after inoculation, without definite changes in serum bilirubin or alkaline phosphatase but with a massive fatty infiltration involving the whole liver lobule.