Monkeypox virus is a species of double-stranded DNA virus which causes monkeypox in humans and other animals. It belongs to the genus Orthopoxvirus in the family Poxviridae. Monkeypox virus is one of the human orthopoxvirus along with variola (VARV), cowpox (CPX), and vaccinia (VACV) viruses. It is not a direct ancestor to, nor a direct descendant of, the variola virus, which causes smallpox. Monkeypox is similar to smallpox, but with a milder rash and lower mortality rate.