Progressive multifocal
leukoencephalopathy (PML)

June 2007     View PDF     En español

What are the symptoms?

Symptoms do not occur when a person is first infected with JC virus. However, when it infects the brain and begins to cause disease, the infection rapidly forms lesions. This begins to affect various body functions controlled by the brain and nervous system.

A frightening aspect of PML is that there’s no “usual” course of disease. Whatever brain areas that are affected by the JC virus will determine how PML appears in an individual. For example, if the virus strikes the part of the brain that controls sight, vision could be lost. If it strikes the part that controls speech or motor skills, one could lose the ability to talk or walk. There is no predicting where or how the virus will attack, and thus what functions will be impaired.

Early symptoms of PML may include weakness in one side of the body or limbs (sometimes very severe), blurred or loss of vision (possibly on one side), fatigue and/or impairments in learned skills that may range from language impairments (aphasia) to memory loss, confusion, disorientation or a loss of balance. Nearly 1 in 5 people with PML disease report having seizures.

Symptoms are similar to those of other HIV-related conditions that affect the brain, including toxoplasmosis (toxo), lymphoma of the central nervous system (CNS lymphoma), AIDS dementia complex (ADC), cryptococcal meningitis, HIV encephalopathy and cytomegalovirus (CMV) and herpes infections of the central nervous system. Therefore, it’s important to consult with a specialist, called a neurologist, when these symptoms occur to assure a correct diagnosis.

PML is most often mistaken for toxo. Typically, a doctor may suspect PML if treatments fail for other conditions, like toxo. PML can also occur at the same time as swelling of the brain (HIV encephalopathy) and toxo.
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