What causes progressive multifocal leukoencephalopathy (PML)?
PML occurs because of the JC virus (JCV) — named after the initials of the first patient identified with it. Up to 85% of all adults have the JC virus. Experts aren’t certain how people contract JCV. There is evidence that children may pick it up through food or water.
In most people, JCV remains inactive and causes no symptoms. But in people with a weak immune system, the virus may progress into PML.
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What are the symptoms of progressive multifocal leukoencephalopathy (PML)?
For most people, PML symptoms start subtly. The symptoms may vary depending on which part of your brain has the infection.
Early symptoms may include:
- Clumsiness or lack of coordination.
- Difficulty speaking.
- Weakness.
As the infection progresses, people may experience:
- Dementia.
- Speech loss.
- Vision loss.
Some people may experience headaches or epilepsy, although these symptoms are rare. Eventually, PML usually progresses. The condition is often fatal, but the outlook varies according to the underlying condition and response to treatment.
