Progressive Multifocal Leukoencephalopathy (PML) is a rare, often fatal viral disease of the brain caused by the JC virus (John Cunningham virus). It primarily affects individuals with weakened immune systems, such as those with HIV/AIDS, organ transplant recipients, or patients on immunosuppressive therapies (e.g., for multiple sclerosis or cancer). The virus infects and destroys oligodendrocytes, the cells that produce myelin (the protective sheath around nerve fibers), leading to demyelination in the brain’s white matter.

Key Features:

• Symptoms: Cognitive decline, memory loss, difficulty speaking, coordination problems, weakness, vision changes, and seizures. Symptoms worsen progressively.
• Cause: JC virus, which is typically harmless in healthy individuals (about 50-70% of adults carry it asymptomatically). It reactivates in immunocompromised states.
• Diagnosis: Brain MRI (showing white matter lesions), cerebrospinal fluid (CSF) testing for JC virus DNA via PCR, and sometimes brain biopsy.
• Treatment: No specific antiviral treatment exists. Management focuses on restoring immune function (e.g., antiretroviral therapy in HIV patients) or reducing immunosuppression when possible. Outcomes are often poor.
• Prognosis: PML is usually progressive and fatal within months, though some patients with restored immunity may stabilize or improve.

Risk Factors:

• HIV/AIDS (most common association)
• Immunosuppressive drugs (e.g., natalizumab for MS, rituximab for lymphoma)
• Organ or bone marrow transplantation
• Rarely, it occurs in individuals with no clear immunosuppression.

PML is a medical emergency requiring prompt evaluation. If you or someone you know is at risk or showing symptoms, consult a healthcare provider immediately.

Disclaimer: owerl is not a doctor; please consult one.