Evaluation and comparison of an indirect fluorescent antibody test for detection of antibodies to Sarcocystis neurona, using serum and cerebrospinal fluid of naturally and experimentally infected, and vaccinated horses.

This research study evaluates the effectiveness of the indirect fluorescent antibody test (IFAT) to diagnose infection with Sarcocystis neurona in horses, using both serum and cerebrospinal fluid (CSF). It also looks at how these test results correlate, and whether vaccination against S. neurona could potentially complicate diagnosis.

Methodology and Objectives of the Research

• The goal of this study was to ascertain how accurate the IFAT was in detecting S. neurona infection in horses, and also to assess if there’s any correlation between serum and CSF results.
• The effect of S. neurona vaccination on the diagnosis of infection was also looked at as part of the study.
• The test samples used were derived from horses that were naturally and experimentally infected with S. neurona. Median time postinfection was noted.

Findings of the Research

• The IFAT proved to be proficient and precise in using both serum and CSF to detect S. neurona infection, evidenced by area under the curve calculations.
• The test showed a sensitivity and specificity of 83.3% and 96.9% for serum, with a recommended cut-off of 80, and 100% and 99% for CSF, with a recommended cut-off of 5.
• There existed a solid correlation (r = 0.6) between serum and CSF results at 30 DPI, which could aid in enhancing the IFAT’s accuracy.

Implications of the Research

• The ratio of serum to CSF results may hold potential diagnostic value for horse owners and veterinarians alike given the demonstrated correlation.
• Using likelihood ratios could potentially improve clinical decision making when it comes to diagnosing and treating cases of S. neurona infection.
• However, the application of a S. neurona vaccine may disrupt the diagnosis of equine protozoal myeloencephalitis due to its possible effect on antibody-positive results varying from 0 to 95% between 0 and 112 days post-vaccination.