Hepatitis D emerged in the past 100 years, without being a zoonosis
Hepatitis D is a virus which is able to replicate only in the presence of a hepatitis B co-infection. It causes the same symptoms as the hepatitis B virus, but with greater severity and lethality. In developed countries, it is rare except among intravenous drug users.
It was discovered in 1977, although epidemics of Lábrea fever in the 1950s were later determined to be caused by the virus. Comparisons of known strains and the mutation rate suggest a common ancestor around the year 1930.
Hepatitis D is the smallest known animal virus (less than 1700 nucleotides), and is the only species in the Deltavirus genus. There is no known animal reservoir. The most similar known animal virus shares only 32% of the nucleotides of hepatitis D.
According to its Wikipedia page,
It has been proposed that HDV may have originated from a class of plant pathogens called viroids, which are much smaller than viruses.