Immunoconversion against Sarcocystis neurona in normal and dexamethasone-treated horses challenged with S. neurona sporocysts

Clinical Diagnosis of Equine Protozoal Myeloencephalitis (EPM)*

“…4 At present, however, there are no published data to suggest that this semiquantitative immunoblot is of any greater value than results obtained by other immunoblot methods for diagnosis of EPM.…”

“…These results indicate a high degree of concordance for both serum (82%) and CSF (85%), and there is no identifiable trend among the disparate results. 4 Thus, at present it is not possible to recommend use of one laboratory over another for immunoblot testing.…”

“…A single, unitless value (0-100) is reported as the relative quantity (RQ). 4 Higher RQ values are suggestive of greater amounts of antibody against the 17-kd antigen, and this value is expected to decline during successful treatment. The clinical relevance of the RQ is unclear.…”

Immunopathologic Effects Associated With Sarcocystis Neurona–infected Interferon-Gamma Knockout Mice

“…This suggests that in most horses, normal immune function prevents clinical disease. In fact, many attempts to develop a repeatable equine model have been unsuccessful (Fenger et al, 1997;Cutler et al, 2001;Saville et al, 2001), most likely because of effective host immune response preventing clinical disease. Some researchers have attempted to develop mouse models that exhibit neurologic disease; however, only immunodeficient mice (Marsh et al, 1997;Lindsay and Dubey, 1999;Fritz and Dubey, 2002) appear to succumb to infection.…”

Equine Protozoal Myeloencephalitis: An Updated Consensus Statement with a Focus on Parasite Biology, Diagnosis, Treatment, and Prevention

“…Factors such as variations in protozoal inoculum and stress‐induced immune suppression have been implicated in the occurrence of EPM 36, 37, 38. However, efforts to increase stress (ie, by additional transport of infected horses) and treatment with immunosuppressive steroids did not cause a concomitant increase in disease severity 39, 40. Genetic variation has been observed among the strains of S. neurona that have been analyzed,41, 42, 43 and there is some evidence that specific parasite genotypes may be particularly virulent in marine mammals 44.…”