MedGen

Any disease caused by a virus. [from NCI]

A progressive demyelination within the central nervous system associated with reactivation of a latent JC virus infection. [from NCI]

Infections with polyomavirus, which are often cultured from the urine of kidney transplant patients. Excretion of bk virus is associated with ureteral strictures and cystitis, and that of jc virus with progressive multifocal leukoencephalopathy (leukoencephalopathy, progressive multifocal). [from MONDO]

An inflammation of brain parenchyma due to infection with a virus. Viral encephalitis can occur as a rare complication of common infections (eg, herpes virus infections) or can occur as a characteristic presentation of rare viruses (eg, rabies virus infection). Encephalitis may be the only neurologic manifestation of infection, or may occur in association with meningitis, myelitis, radiculitis, or neuritis. Viral encephalitis is associated with neurological dysfunction. [from HPO]

A disorder of the brain caused by an infectious agent that presents with fever, headache, and an altered level of consciousness. There may also be focal or multifocal neurologic deficits, and focal or generalized seizure activity. [from HPO]

Viral infections of the brain, spinal cord, meninges, or perimeningeal spaces. [from MeSH]

This term describes abnormality of the white matter of the cerebrum resulting from damage to the myelin sheaths of nerve cells. [from HPO]

A broad group of disorders that affect the myelin sheaths that cover the neurons. Myelin sheathes cover neuronal axons in the central and peripheral nervous system and function to increase travelling impulse speeds. Disruption of this sheath impairs neuronal transmission and can result in disorders such as multiple sclerosis and Guillain-Barre syndrome, among others. [from NCI]

An inflammatory process affecting the brain parenchyma. Causes include viral infections and less frequently bacterial infections, toxins, and immune-mediated processes. [from NCI]