Diagnostic value of detecting JC virus DNA in cerebrospinal fluid of patients with progressive multifocal leukoencephalopathy.

JC virus DNA was detected by PCR in the cerebrospinal fluid of 17 of 23 (73.9%) patients with confirmed cases of progressive multifocal leukoencephalopathy and 2 of 48 (4.2%) controls without progressive multifocal leukoencephalopathy. The sensitivity and specificity of this PCR were 74 and 95.8%, respectively, while the positive and negative predictive values were 89.5 and 88.5%, respectively.