The John Cunningham virus, or JC virus (JCV) causes PML. JC virus is also known as human polyomavirus 2. By age 10, most people have been infected with this virus though it hardly ever causes symptoms. But people with a weakened immune system are at risk of developing PML. Causes of a weakened immune system include:
- HIV/AIDS (less common cause of PML now because of better management of HIV/AIDS).
- Certain medicines that suppress the immune system called monoclonal antibodies. Such medicines may be used to prevent organ transplant rejection or to treat multiple sclerosis, rheumatoid arthritis and other autoimmune disorders, and related conditions.
- Cancers, such as leukemia and Hodgkin lymphoma.
Symptoms may include any of the following:
- Loss of coordination, clumsiness
- Loss of language ability (aphasia)
- Memory loss
- Vision problems
- Weakness of the legs and arms that gets worse
- Personality changes
In people with HIV/AIDS, treatment to strengthen the immune system can lead to recovery from the symptoms of PML. No other treatments have proved effective for PML.
PML is a life-threatening condition. Depending on how severe the infection is, up to one half of people diagnosed with PML die within the first few months.Talk to your provider about care decisions.
PML; John Cunningham virus; JCV; Human polyomavirus 2; JC virus
Berger JR, Nath A. Cytomegalovirus, Epstein-Barr virus, and slow virus infections of the central nervous system. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 346.
Tan CS, Koralnik IJ. JC, BK, and other polyomaviruses: progressive multifocal leukoencephalopathy (PML). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 144.
Review Date 2/4/2020
Updated by: Amit M. Shelat, DO, FACP, FAAN, Attending Neurologist and Assistant Professor of Clinical Neurology, Stony Brook University School of Medicine, Stony Brook, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.