Abstract: Acetylcholine and its receptors appeared in evolution before development of a nervous system. Cholinergic agonists functions include proliferation, differentiation, and cell-to-cell contact in protozoa] as well as vertebrate cells. Animal models for infection by Apicomplexan parasites require cell-to-cell contact followed by differentiation of parasite and host cells to produce clinical disease. Experimental infections are produced by introducing parasite infected leukocytes into a host. Binding cholinergic receptors on the parasites and leukocytes with levamisole HCl induces non-progressive infections and absence of signs of disease.

Abstract: Equine protozoal myeloencephalitis (EPM) is the most commonly diagnosed infectious neuro-degenerative in horses. Important advances have been made in the biology of S. neurona but little attention has been paid to the inflammatory component of disease although neuroinflammation is present in all definitively diagnosed cases of EPM. Polyneuritis equi (cauda equina neuritis) of horses is a rarely recognized non-infectious, chronic relapsing, peripheral neurodegenerative disorder in horses. We propose that polyneuritis equi may be associated with Sarcocystis neurona infections. We demonstrate the presence of serum antibodies against myelin proteins and S. neurona surface antigens in 78% (n=55) ataxic horses with a presumptive diagnosis of EPM. Serum antibodies against S. neurona were detected in a horse with histopathologically confirmed polyneuritis equi, also sarcocysts were observed by histopathology.