Confirmation of results of tests for West Nile virus infection in organ transplant recipients.

of diagnostic tests, and it is appropriate to highlight its importance—particularly in the case of primary CNS lymphoma, which has decreased in prevalence since the advent of combination antiretroviral therapy [3–5]. Variability in nucleic acid amplification protocols between laboratories may result in varying levels of assay sensitivity. Our report aims, in part, to emphasize how EBV DNA PCR performs in a clinical setting that is commonly encountered in developed countries—specifically, in situations in which a commercial or commercially affiliated laboratory offers a novel diagnostic test for physicians in practice. These physicians often have no control over how the test is set up or performed. We believe our results have particular relevance for physicians practicing under such circumstances. We agree that, as for any nonstandardized test, the potential for variability should be carefully considered when EBV DNA PCR results are interpreted in the course of evaluation of patients with HIV infection and CNS disease.