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Accurate Antemortem Diagnosis of Equine Protozoal Myeloencephalitis ( EPM ) Based on Detecting Intrathecal Antibodies against Sarcocystis neurona Using the Sn SAG 2 and Sn SAG 4/3 ELISA s
Background Recent work demonstrated the value of antigen‐specific antibody indices ( AI and C‐value) to detect intrathecal antibody production against S arcocystis neurona for antemortem diagnosis of equine protozoal myeloencephalitis ( EPM ). Objectives The study was conducted to assess whether the...
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Published in: | Journal of veterinary internal medicine 2013-09, Vol.27 (5), p.1193-1200 |
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Main Authors: | , , , , , , , , , |
Format: | Article |
Language: | English |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Background
Recent work demonstrated the value of antigen‐specific antibody indices (
AI
and C‐value) to detect intrathecal antibody production against
S
arcocystis neurona
for antemortem diagnosis of equine protozoal myeloencephalitis (
EPM
).
Objectives
The study was conducted to assess whether the antigen‐specific antibody indices can be reduced to a simple serum : cerebrospinal fluid (
CSF
) titer ratio to achieve accurate
EPM
diagnosis.
Animals
Paired serum and
CSF
samples from 128 horses diagnosed by postmortem examination. The sample set included 44
EPM
cases, 35 cervical‐vertebral malformation (
CVM
) cases, 39 neurologic cases other than
EPM
or
CVM
, and 10 non‐neurologic cases.
Methods
Antibodies against
S
. neurona
were measured in serum and
CSF
pairs using the Sn
SAG
2 and Sn
SAG
4/3 (Sn
SAG
2, 4/3)
ELISA
s, and the ratio of each respective serum titer to
CSF
titer was determined. Likelihood ratios and diagnostic sensitivity and specificity were calculated based on serum titers,
CSF
titers, and serum :
CSF
titer ratios.
Results
Excellent diagnostic sensitivity and specificity was obtained from the Sn
SAG
2, 4/3 serum :
CSF
titer ratio. Sensitivity and specificity of 93.2 and 81.1%, respectively, were achieved using a ratio cutoff of ≤100, whereas sensitivity and specificity were 86.4 and 95.9%, respectively, if a more rigorous cutoff of ≤50 was used. Antibody titers in
CSF
also provided good diagnostic accuracy. Serum antibody titers alone yielded much lower sensitivity and specificity.
Conclusions and Clinical Importance
The study confirms the value of detecting intrathecal antibody production for antemortem diagnosis of
EPM
, and they further show that the antigen‐specific antibody indices can be reduced in practice to a simple serum :
CSF
titer ratio. |
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ISSN: | 0891-6640 1939-1676 |
DOI: | 10.1111/jvim.12158 |