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Am J Vet Res. 2006 May;67(5):869-76.

Indirect fluorescent antibody testing of cerebrospinal fluid for diagnosis of equine protozoal myeloencephalitis.

Author information

1
Animal Population Health Institute, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523-1681, USA.

Abstract

OBJECTIVE:

To assess the use of CSF testing with an indirect fluorescent antibody test (IFAT) for diagnosis of equine protozoal myeloencephalitis (EPM) caused by Sarcocystis neurona.

SAMPLE POPULATION:

Test results of 428 serum and 355 CSF samples from 182 naturally exposed, experimentally infected, or vaccinated horses.

PROCEDURE:

EPM was diagnosed on the basis of histologic examination of the CNS. Probability distributions were fitted to serum IFAT results in the EPM+ and EPM-horses, and correlation between serum and CSF results was modeled. Pairs of serum-CSF titers were generated by simulation, and titer-specific likelihood ratios and post-test probabilities of EPM at various pretest probability values were estimated. Post-test probabilities were compared for use of a serum-CSF test combination, a serum test only, and a CSF test only.

RESULTS:

Post-test probabilities of EPM increased as IFAT serum and CSF titers increased. Post-test probability differences for use of a serum-CSF combination and a serum test only were < or = 19% in 95% of simulations. The largest increases occurred when serum titers were from 40 to 160 and pre-test probabilities were from 5% to 60%. In all simulations, the difference between pre- and post-test probabilities was greater for a CSF test only, compared with a serum test only.

CONCLUSIONS AND CLINICAL RELEVANCE:

CSF testing after a serum test has limited usefulness in the diagnosis of EPM. A CSF test alone might be used when CSF is required for other procedures. Ruling out other causes of neurologic disease reduces the necessity of additional EPM testing.

PMID:
16649923
DOI:
10.2460/ajvr.67.5.869
[Indexed for MEDLINE]

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