Infectious Disease Compendium

JC virus


A virus.

Epidemiologic Risks

Part of life, most are seropositive by age 14. Found in high concentrations in urban sewage, so maybe contaminated water is the route of spread. It is mostly found in the GI tract but it can also infect brains and kidneys.


Progressive Multifocal Leukoencephalopathy in AIDS and transplant patients. A variety of biologics like natalizumab and other mabs (not Queen Mab (PubMed) however are associated with PML as well.

Granule cell neuronopathy leading to cerebellar ataxia (PubMed), at least in patients with immunosuppression and chronic lymphopenia.

Diagnose with PCR on CSF but those on natalizumab may have small lesions and a false negative PCR (PubMed).

Also, blood PCR is occasionaly positive when the CSF is negative and not all CSF is readily available for testing (PubMed).




Named after a patient with PML, John Cunningham.

Curious Cases

Relevant links to my Medscape blog

Old OI's Return

Last update: 07/04/18