title: Utility of 2 immunological tests for antemortem diagnosis of equine protozoal myeloencephalitis (Sarcocystis neurona Infection) in naturally occurring cases.
abstract: BACKGROUND
  Antemortem diagnosis of equine protozoal myeloencephalitis (EPM) is challenging. Limited information is available regarding a commercial test (surface antigen 1 [SAG-1] ELISA). Performance of another commercial test (indirect fluorescent antibody test [IFAT]) using samples from an independent group has not been well described.
  
  
  OBJECTIVE
  The primary goal was to evaluate the SAG-1 ELISA and IFAT using naturally occurring EPM cases. A secondary goal was to obtain more information regarding clinical presentation.
  
  
  METHODS
  Hospital cases were admitted over 20 months and classified into 4 groups. Confirmed positive cases (n = 9) had asymmetric or multifocal neurologic deficits or both and postmortem lesions consistent with EPM. Confirmed negative cases (n = 17) had variable clinical signs and postmortem lesions consistent with another neurologic disease (or no lesions). Suspected positive cases (n = 10) had asymmetric or multifocal deficits or both, marked improvement after treatment for EPM, and other likely diseases excluded. Suspected negative cases (n = 29) had orthopedic disease and no neurologic deficits.
  
  
  METHODS
  Results of immunological testing (SAG-1 ELISA and IFAT on serum or cerebrospinal fluid [CSF] or both), neurologic examinations, CSF analyses, and postmortem examinations were analyzed retrospectively.
  
  
  RESULTS
  SAG-1 ELISA sensitivity was 12.5% (95% CI, 1.6-38.4) and specificity was 97.1% (95% CI, 84.7-99.9) using serum. IFAT sensitivity was 94.4% (95% CI, 72.7-99.9) and specificity was 85.2% (95% CI, 66.3-95.8) using serum; sensitivity was 92.3% (95% CI, 64.0-99.8) and specificity was 89.7% (95% CI, 72.7-97.8) using CSF.
  
  
  CONCLUSIONS
  Low sensitivity of the SAG-1 ELISA limited its usefulness for antemortem diagnosis of EPM in this patient population.
authors: Department of Clinical Studies, New Bolton Center, University of Pennsylvania School of Veterinary Medicine, Kennett Square, PA, USA. amyjohn@vet.upenn.edu
authors: A L
authors: AL
authors: Johnson
authors: A J
authors: AJ
authors: Burton
authors: R W
authors: RW
authors: Sweeney
mesh_terms: D000818:Animals; D004679:Encephalomyelitis / Q000175:diagnosis / Q000469:parasitology / Q000662:veterinary*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods / Q000662:veterinary*; D019084:Fluorescent Antibody Technique, Indirect / Q000379:methods / Q000662:veterinary*; D006734:Horse Diseases / Q000175:diagnosis* / Q000276:immunology / Q000469:parasitology; D006736:Horses; D012189:Retrospective Studies; D012522:Sarcocystis / Q000276:immunology*; D012523:Sarcocystosis / Q000175:diagnosis / Q000662:veterinary*; D012680:Sensitivity and Specificity