Abstract: The present invention provides an immunogenically active component comprising inactivated Sarcocystis neurona cells and/or inactivated Neospora hughesi cells; antigens derived therefrom; DNA derived therefrom; or a mixture; or in combination with other vaccine components thereof. Further provided are vaccine compositions useful for preventing or ameliorating equine protozoal myeloencephalitis infection and disease and a method for the cell culture propagation of protozoan parasites.