Ask the Experts - Low HIV Viral Load in Patient With PML?
A patient newly diagnosed with HIV has clinical findings and brain MRI consistent with progressive multifocal leukoencephalopathy (PML), yet his initial viral load is only 10,000 copies/mL, verified on repeat labs 2 days apart. His CD4+ count, however, is 18 cells/mm. After 4 weeks of HAART, his viral load is now below 50 copies/mL, and his CD4+ count is 25 cells/mm. Any comments on such a low baseline viral load in a patient with such advanced disease?

PML may be the first clinical manifestation of HIV disease in up to 20% of patients presenting with PML. In the case under discussion, it is not clear whether confirmatory diagnostic tests for PML were performed, such as polymerase chain reaction assay for JC virus in cerebrospinal fluid or brain biopsy. While clinical findings and brain MRI findings are suggestive of diagnosis, one should establish diagnosis with 1 of the above tests.

Several factors have been proposed as prognostic markers for the course of PML, including CD4+ count, radiologic appearance of the lesions (ie, degree of contrast enhancement), and degree of inflammation on histologic specimens. However, Clifford and colleagues have reported that suppressed plasma HIV viral load is the strongest prognostic factor for an improved course of disease. While the mean survival of patients with PML was approximately 3-4 months in the pre-HAART era, it is not uncommon for patients whose plasma HIV viral load has been suppressed by HAART to survive with stable neurologic status for several years. Apart from suppressing plasma viral load with HAART, patients should be followed by a neurologist experienced in HIV in order to monitor their neurologic status.

A controlled trial of intravenous or intrathecal cytarabine demonstrated no efficacy in the treatment of PML. Case series have suggested efficacy of alpha-interferon or cidofovir. The AIDS Clinical Trials Group has recently completed a prospective open-label trial of cidofovir in the treatment of AIDS-related PML. Data from this study should be available within the next 12 months.