Determination of the activity of diclazuril against Sarcocystis neurona and Sarcocystis falcatula in cell cultures.

Diclazuril is a benzeneacetonitril anticoccidial that has excellent activity against the extraintestinal stages of Toxoplasma gondii and Neospora caninum. It also is highly active against intestinal coccidia of poultry. The present study examined the efficacy of diclazuril in inhibiting merozoite production of Sarcocystis neurona and Sarcocystis falcatula in bovine turbinate cell cultures. Diclazuril inhibited merozoite production by more than 80% in cultures of S. neurona or S. falcatula treated with 0.1 ng/ml diclazuril and greater than 95% inhibition of merozoite production was observed when infected cultures were treated with 1.0 ng/ml diclazuril. Diclazuril may have promise as a therapeutic agent in the treatment of S. neurona-induced equine protozoal myeloencephalitis in horses and S. falcatula infections in birds.