Electron microscopical study on the effect of halofuginone on Theileria parva.

The effect of halofuginone (Stenorol) on schizonts of Theileria parva was studied by means of the electron microscope. After administration of 1,2 mg halofuginone per kg, it was observed that infected lymphocytes burst apart, whereas the intracellular parasites were at first little affected, showing some expansion of the perinuclear spaces. Once they were released from the cells, the schizonts degenerated completely. Apparently they are not capable of surviving outside the host cells. Probably this is due to the lack of a pellicle, which is characteristic for motile (i.e. normally extracellular) stages. The destruction of parasitized host cells occurred very rapidly, so that no infected cells could be observed 126 h after treatment. Uninfected lymphocytes were not affected by the drug.