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Indirect fluorescent antibody test and surface antigen ELISAs for antemortem diagnosis of equine protozoal myeloencephalitis.
Abstract: 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.
Copyright © 2013 by the American College of Veterinary Internal Medicine.
Publication Date: 2013-03-20 PubMed ID: 23517480DOI: 10.1111/jvim.12061Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- Non-U.S. Gov't
- Antibodies
- Cerebrospinal Fluid
- Clinical Pathology
- Clinical Study
- Diagnostic Technique
- Disease Diagnosis
- Enzyme-Linked Immunosorbent Assay (ELISA)
- Equine Health
- Equine Protozoal Myeloencephalitis
- Horses
- Immunofluorescence Assay
- Infectious Disease
- Neurological Diseases
- Post Mortem
- Sarcocystis
- Sensitivity and Specificity
- Serum
- Veterinary Medicine
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
This study focuses on testing the effectiveness of two commercially available tests for diagnosing equine protozoal myeloencephalitis (EPM): the indirect fluorescent antibody test (IFAT) and the surface antigen 2, 4/3 ELISA (SAG2, 4/3 ELISA). The research suggests that the most accurate diagnosis of EPM can be achieved through calculating the serum to cerebrospinal fluid (CSF) titer ratios using the SAG2, 4/3 ELISA method.
Methods and Objective of the Study
- The objective of the research was to examine the effectiveness of IFAT and SAG2, 4/3 ELISA tests in diagnosing equine protozoal myeloencephalitis (EPM).
- The researchers used paired samples of serum and CSF earlier collected from four types of clinical patients.
- Among these patients, some were confirmed positive cases (those with clear neurological deficits and postmortem lesions indicative of EPM), confirmed negative cases (those with differing symptoms and lesions associated with other diseases), suspected positive cases (showed symptoms similar to EPM and recovered after treatment), and suspected negative cases (those having variable signs but were highly suspected of having a different disease).
Implementing and Analyzing the Tests
- The researchers conducted two testing procedures (IFAT and SAG2, 4/3 ELISA) on the samples and calculated the serum : CSF titer ratio for each. The results were then analyzed independently, and against each other.
- The overall accuracy and sensitivity of the tests were calculated. Sensitivity refers to the ability of the test to correctly identify those with the disease, while accuracy evaluates both the true positive rate and the true negative rate.
Results from the Study
- The highest overall accuracy was recorded for the SAG2, 4/3 ELISA titer ratio test at 0.97 with sensitivity at 0.88.
- The IFAT test also showed high accuracy at 0.88, but its sensitivity was lower, at 0.65.
- Both tests had a high positive predictive value, as shown by their specificity measurement, with the SAG2, 4/3 ELISA offering a perfect score of 1.
Conclusions Drawn
- The research concluded that using only serum results for diagnosis was the least accurate method for both tests.
- The most accurate methods include the SAG2, 4/3 ELISA serum : CSF titer ratio, highlighting its better utilization in diagnosing EPM.
Cite This Article
APA
Johnson AL, Morrow JK, Sweeney RW.
(2013).
Indirect fluorescent antibody test and surface antigen ELISAs for antemortem diagnosis of equine protozoal myeloencephalitis.
J Vet Intern Med, 27(3), 596-599.
https://doi.org/10.1111/jvim.12061 Publication
Researcher Affiliations
- Department of Clinical Studies - New Bolton Center, University of Pennsylvania School of Veterinary Medicine, Kennett Square, PA 19348, USA. amyjohn@vet.upenn.edu
MeSH Terms
- Animals
- Antigens, Protozoan / isolation & purification
- Antigens, Surface / blood
- Encephalomyelitis / parasitology
- Encephalomyelitis / veterinary
- Enzyme-Linked Immunosorbent Assay / veterinary
- Fluorescent Antibody Technique, Indirect / veterinary
- Horse Diseases / diagnosis
- Horse Diseases / parasitology
- Horses
- Sarcocystis / metabolism
- Sarcocystosis / diagnosis
- Sarcocystosis / veterinary
Citations
This article has been cited 9 times.- Enriquez CK, Morrow JK, Graves A, Johnson A. Evaluation of real-time polymerase chain reaction for the diagnosis of protozoal myeloencephalitis in horses using cerebrospinal fluid. J Vet Intern Med 2023 Sep-Oct;37(5):1893-1898.
- Bedenice D, Johnson AL. Neurologic conditions in the sport horse. Anim Front 2022 Jun;12(3):37-44.
- Boorman S, Scherrer NM, Stefanovski D, Johnson AL. Facial nerve paralysis in 64 equids: Clinical variables, diagnosis, and outcome. J Vet Intern Med 2020 May;34(3):1308-1320.
- Mittelman NS, Stefanovski D, Johnson AL. Utility of C-reactive protein and serum amyloid A in the diagnosis of equine protozoal myeloencephalitis. J Vet Intern Med 2018 Sep;32(5):1726-1730.
- Schale S, Howe D, Yeargan M, Morrow JK, Graves A, Johnson AL. Protozoal coinfection in horses with equine protozoal myeloencephalitis in the eastern United States. J Vet Intern Med 2018 May;32(3):1210-1214.
- Barberini DJ, Aleman M, Aristizabal F, Spriet M, Clark KC, Walker NJ, Galuppo LD, Amorim RM, Woolard KD, Borjesson DL. Safety and tracking of intrathecal allogeneic mesenchymal stem cell transplantation in healthy and diseased horses. Stem Cell Res Ther 2018 Apr 10;9(1):96.
- Reed SM, Furr M, Howe DK, Johnson AL, MacKay RJ, Morrow JK, Pusterla N, Witonsky S. Equine Protozoal Myeloencephalitis: An Updated Consensus Statement with a Focus on Parasite Biology, Diagnosis, Treatment, and Prevention. J Vet Intern Med 2016 Mar-Apr;30(2):491-502.
- Mullen KR, Furness MC, Johnson AL, Norman TE, Hart KA, Burton AJ, Bicahlo RC, Ainsworth DM, Thompson MS, Scrivani PV. Adverse reactions in horses that underwent general anesthesia and cervical myelography. J Vet Intern Med 2015 May-Jun;29(3):954-60.
- Valderrama-Martinez C, Packham A, Zheng S, Smith W, Plancarte M, Aleman M. Effect of refrigeration, room temperature, and processing time on serum immunofluorescent antibody titers for Sarcocystis neurona. J Vet Intern Med 2025 Jan-Feb;39(1):e17282.
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