slow-vi·rus dis·ease(slō vī'rŭs di-zēz')
1. An older term for any disease caused by spongiform encephalopathies, including kuru of humans and scrapie of sheep, classified as slow virus disease but now recognized as prion protein disease.
2. A disorder that follows a slow, progressive course spanning months to years, frequently involving the central nervous system and ultimately leading to death, such as subacute sclerosing panencephalitis, seemingly caused by the measles virus.