Experimental therapy of theileriosis.

A tissue culture method was used to screen compounds for activity against Theileria parva, and demonstrated that the hydroxy-alkylated naphthoquinones, 'menoctone' and 993C were highly active, with ED50 values around 0,005 mg/l. When injected into cattle artificially infected the T. parva, menoctone cured all of 7 cattle at a total dosage of 10 mg/kg injected intravenously (i.v.). A further trial showed that injection of menoctone, 10 mg/kg, as a single dose gby the intramuscular (i.m.) route was more effective than when a similar dose was given by the i.v. route. Titration of serum from these cattle in the in vitro system showed that inhibitory levels of drug persisted for three days after i.v. injection and six days when menoctone was injected i.m. The minimum effective dose level of 993C was 20 mg/kg i.m. either as a single dose, or as two doses of 10 mg/kg with an interval of 48 hours.