Evaluation of real-time polymerase chain reaction for the diagnosis of protozoal myeloencephalitis in horses using cerebrospinal fluid.
Abstract: Equine protozoal myeloencephalitis (EPM) caused by Sarcocystis neurona remains an antemortem diagnostic challenge in some horses. Recent work suggested the use of real-time PCR (rtPCR) on cerebrospinal fluid (CSF) as a promising diagnostic tool. Objective: To evaluate the sensitivity and specificity of S. neurona rtPCR on CSF for EPM diagnosis using horses with EPM and S. neurona-seropositive horses with other neurologic conditions. Methods: Ninety-nine horses with neurologic disease that underwent complete neurologic examination, CSF collection, and, if euthanized, necropsy including the central nervous system (CNS). Methods: Retrospective case-control study using banked CSF samples. Samples from horses with neurologic abnormalities and necropsy-confirmed EPM diagnosis, presumptive EPM diagnosis using strict criteria (SnSAG2/4/3 ELISA serum:CSF titer ratios <50) and horses diagnosed with other neurologic diseases were used. Results: Fifty-two horses had EPM; 23 were confirmed on necropsy, and 29 were presumptive clinical diagnoses. The other 47 horses all had necropsy-confirmed diagnoses. Four of the 47 horses had normal neurologic findings on necropsy and the remaining 43 horses had neurologic diseases including equine degenerative myeloencephalopathy (EDM), cervical vertebral stenotic myelopathy, trauma, and other miscellaneous conditions. One CSF sample was weakly positive for S. neurona by rtPCR, this sample was obtained from a horse with confirmed EDM. Samples from the other 98 horses were negative for S. neurona by rtPCR. Conclusions: Our study contradicts previous conclusions that S. neurona rtPCR is potentially useful for EPM diagnosis, because our results indicate that the assay has a low sensitivity (0%) for EPM.
© 2023 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.
Publication Date: 2023-08-07 PubMed ID: 37549306PubMed Central: PMC10472993DOI: 10.1111/jvim.16826Google Scholar: Lookup
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- Journal Article
- Cerebrospinal Fluid
- Clinical Pathology
- Clinical Study
- Diagnostic Technique
- Disease Diagnosis
- Equine Diseases
- Equine Health
- Equine Protozoal Myeloencephalitis
- Equine Science
- Horses
- Infection
- Necropsy
- Neurological Diseases
- Polymerase Chain Reaction
- Post Mortem
- Real-Time PCR
- Retrospective Study
- Sarcocystis
- Veterinary Medicine
- Veterinary Research
Summary
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This study evaluates the effectiveness of real-time PCR on cerebrospinal fluid for diagnosing Equine protozoal myeloencephalitis, a neurological disease in horses. The results suggest that this method is not as reliable as previous research has indicated due to its low sensitivity.
Research Objectives
- The objective of the study was to evaluate the sensitivity and specificity of a diagnostic tool known as real-time PCR when used on horses’ cerebrospinal fluid for the diagnosis of Equine protozoal myeloencephalitis (EPM). This is a disease caused by a parasite, Sarcocystis neurona.
Research Methodology
- Researchers used a retrospective case-control study design and samples of cerebrospinal fluid from 99 horses with neurological disease.
- The samples were divided into two groups: those from horses with confirmed EPM and those from horses with other neurological conditions.
- Specimens from horses with other identified neurologic disorders were used as controls.
- Real-time PCR was then applied to the samples to try to detect the presence of the Sarcocystis neurona parasite.
Research Findings
- The test confirmed the existence of EPM in 52 out of the 99 horses. Out of these, 23 were confirmed through necropsy while 29 were presumptive clinical diagnoses.
- Of the remaining 47 horses, all of them had necropsy-confirmed diagnoses of other conditions not related to EPM.
- Out of all the samples tested, only one was weakly positive for S. neurona when tested using real-time PCR. This sample belonged to a horse diagnosed with Equine degenerative myeloencephalopathy (EDM), a different neurological condition.
- The remaining 98 samples all tested negative for Sarcocystis neurona using this method.
Conclusion
- Based on the results of their study, the researchers concluded that real-time PCR has a low sensitivity for diagnosing EPM. This means it is unlikely to correctly identify horses that are actually suffering from the disease.
- The study contradicts previous research suggesting real-time PCR to be a promising diagnostic tool to detect EPM in horses.
Cite This Article
APA
Enriquez CK, Morrow JK, Graves A, Johnson A.
(2023).
Evaluation of real-time polymerase chain reaction for the diagnosis of protozoal myeloencephalitis in horses using cerebrospinal fluid.
J Vet Intern Med, 37(5), 1893-1898.
https://doi.org/10.1111/jvim.16826 Publication
Researcher Affiliations
- Department of Clinical Studies, University of Pennsylvania New Bolton Center Hospital for Large Animals, Kennett Square, Pennsylvania, USA.
- Equine Diagnostic Solutions, LLC, Lexington, Kentucky, USA.
- Equine Diagnostic Solutions, LLC, Lexington, Kentucky, USA.
- Department of Clinical Studies, University of Pennsylvania New Bolton Center Hospital for Large Animals, Kennett Square, Pennsylvania, USA.
MeSH Terms
- Horses
- Animals
- Sarcocystosis / diagnosis
- Sarcocystosis / veterinary
- Real-Time Polymerase Chain Reaction / veterinary
- Retrospective Studies
- Case-Control Studies
- Sarcocystis / genetics
- Encephalomyelitis / diagnosis
- Encephalomyelitis / veterinary
- Horse Diseases / diagnosis
Grant Funding
- Raymond Firestone Trust/Raker/Tulleners Fund/Tamworth Fund from the Department of Clinical Studies, New Bolton Center. University of Pennsylvania.
Conflict of Interest Statement
Amy Graves and Jennifer Morrow work at Equine Diagnostic Solutions (EDS), the laboratory at which study samples were processed. The S. neurona rtPCR in cerebrospinal fluids test is commercially available at EDS. Our results indicate poor diagnostic value for this test; therefore, eliminating risk of bias. No other authors declare a conflict of interest.
References
This article includes 18 references
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