The anthelmintic effects of a new compound "E" (Friedheim) on Onchocerca gutturosa in the cow--a possible tertiary screening system for drug action against O. volvulus in man.

Three cows were treated with different levels of compound "E" which is known to have strong filaricidal activity. In all three animals the number of microfilariae of Onchocerca gutturosa declined after treatment. At autopsy most of the adult worms found were dead and in those still living embryogenesis appeared to have ceased. It is concluded that, despite the disadvantages, this system represents a possible way of assessing onchocercicidal activity before undertaking human trials.