Progressive multifocal leukoencephalopathy (pml)

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Progressive multifocal leukoencephalopathy is a rare infection of the brain that is caused by the JC (John Cunningham) virus.

People with a weakened immune system are most likely to get the disorder.
People may become clumsy, have trouble speaking, and become partially blind, and mental function declines rapidly.
Death usually occurs within 9 months.
Imaging of the head and a spinal tap are done.
Treating the disorder that weakened the immune system may help people live longer.

(See also Overview of Brain Infections.)
Progressive multifocal leukoencephalopathy results from infection by the JC virus. The JC virus is often acquired during childhood. Most adults have been infected with the JC virus but do not develop the disorder.
The virus appears to remain inactive until something (such as a weakened immune system) allows it to be reactivated and start to multiply. Thus, the disorder affects mainly people whose immune system has been weakened by a disorder (such as leukemia, lymphoma, or AIDS) or by drugs that suppress the immune system (Immunosuppressants) or that modify the immune system (immunomodulators). Such drugs include those used to prevent rejection of transplanted organs or to treat cancer or autoimmune disorders, such as systemic lupus erythematosus (lupus) or multiple sclerosis. These drugs include natalizumab and rituximab , which are monoclonal antibodies, and brentuximab vedotin , which is an anticancer drug combined with a specific antibody that targets cancer cells.