Clinical and Serum Antibody Responses of S. neurona Infected Horses Treated with Decoquinate and Levamisole

Sarcocystis neurona are apicomplexan parasites that can cause mortality in domestic and wild animals. Twelve antigen types are described for S. neurona, however just two phenotypes (SnSAG 1 and SnSAG 5) represent the majority of those that are associated with disease. A novel S. falcatula gene, antigenically indistinct from SnSAG 6, was cloned into an expression vector and the recombinant protein was used to determine the presence of antibodies SAG 6 phenotype infections in equine sarcocystosis. Additionally, antibodies to disease-associated SAG phenotypes of Sarcocystis neurona were assayed by indirect ELISA using sera from horses with a presumptive diagnosis of sarcocystosis. The lateral flow Sarcocystis neurona multiplex antibody detection kit (Immy, Norman, OK) was evaluated for the rapid identification of Sarcocystis antibodies. One hundred forty-one horses (141) with a presumptive diagnosis of equine protozoal myeloencephalitis were treated with decoquinate (0.5mG/kG) and levamisole (1 mG/kG) in an oral paste for 10 days and monitored for a treatment response. Successful treatment of equine sarcocystosis was determined by a reduction in clinical signs by clinical neurological exam (93.6%) and a reduction in antibodies 4-6 weeks post treatment (89.3%). The detection of antibody against SAG’s 1 5, 6 and a response to decoquinate/ levamisole identified horses with clinical EPM. The rapid detection of SAG phenotype facilitated treatment and evaluation of clinical response.