Chronic viral infections that are characterized by a long incubation period or a very long course of disease and lead to chronic neurological diseases. They are caused by conventional viruses (retroviruses, papoaviruses) or prions. The developing diseases will not show clinical manifestations until months or years after the initial exposure.
Characteristic slow virus infections are progressive multifocal leukoencephalopathy (subacute progressive demyelinating CNS disease, which occurs mainly as opportunistic infection in patients with immunosuppression) or tropical spastic HIV-associated myelopathy.