hepatitis F (HF), a hypothetical virus linked to hepatitis, possibly a mutation of the hepatitis B virus. The most recent finding was in 1994, when novel viral particles were discovered in the feces of posttransfusion patients without hepatitis A, B, C, or E. When injected into the bloodstream of rhesus monkeys, these particles caused hepatitis. When further investigations failed to confirm the existence of the virus, it was delisted as a cause of infectious hepatitis. Also called Toga virus.
