title: Indirect fluorescent antibody test and surface antigen ELISAs for antemortem diagnosis of equine protozoal myeloencephalitis.
abstract: BACKGROUND
  Recent research suggests that serum : CSF titer ratios could provide the most accurate antemortem diagnosis of equine protozoal myeloencephalitis (EPM) caused by Sarcocystis neurona.
  
  
  OBJECTIVE
  The purpose of this study was to assess the utility of two commercially available tests, the indirect fluorescent antibody test (IFAT) and the surface antigen 2, 4/3 ELISA (SAG2, 4/3 ELISA), using archived paired serum and CSF samples.
  
  
  METHODS
  Samples were obtained from 4 types of clinical patients. Confirmed positive cases (n = 9 horses; 11 sample sets) had neurologic deficits and postmortem lesions consistent with EPM. Confirmed negative cases (n = 28) had variable clinical signs and postmortem lesions consistent with another disease. Suspected positive cases (n = 6) had neurologic deficits consistent with EPM, marked improvement after treatment, and exclusion of other diseases. Suspected negative cases (n = 14) had variable signs with a strong presumptive diagnosis of another disease.
  
  
  METHODS
  For each test, descriptive statistics were calculated using serum results alone, CSF results alone, and a serum : CSF titer ratio.
  
  
  RESULTS
  Overall accuracy was highest for SAG2, 4/3 ELISA titer ratio at 0.97 (95% CI 0.88-0.99) with sensitivity = 0.88 (95% CI 0.66-0.97) and specificity = 1 (95% CI 0.92-1). IFAT CSF and titer ratio results also showed high accuracy at 0.88 (95% CI 0.77-0.94), but lower sensitivity = 0.65 (95% CI 0.41-0.83).
  
  
  CONCLUSIONS
  Using serum results alone was least accurate for both test types. The more accurate methods, such as the SAG2, 4/3 ELISA serum : CSF titer ratio, should be utilized.
authors.affiliation: Department of Clinical Studies - New Bolton Center, University of Pennsylvania School of Veterinary Medicine, Kennett Square, PA 19348, USA. amyjohn@vet.upenn.edu
authors.forename: A L
authors.initials: AL
authors.lastname: Johnson
authors.forename: J K
authors.initials: JK
authors.lastname: Morrow
authors.forename: R W
authors.initials: RW
authors.lastname: Sweeney
mesh_terms: D000818:Animals; D000953:Antigens, Protozoan / Q000302:isolation & purification*; D000954:Antigens, Surface / Q000097:blood; D004679:Encephalomyelitis / Q000469:parasitology / Q000662:veterinary*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary*; D019084:Fluorescent Antibody Technique, Indirect / Q000662:veterinary*; D006734:Horse Diseases / Q000175:diagnosis / Q000469:parasitology*; D006736:Horses; D012522:Sarcocystis / Q000378:metabolism; D012523:Sarcocystosis / Q000175:diagnosis / Q000662:veterinary*
chemical_list: D000953:Antigens, Protozoan; D000954:Antigens, Surface