Monkeypox is a rare disease that is caused by infection with monkeypox virus. It occurs primarily in remote parts of Central and West Africa, near tropical rainforests. Monkeypox virus belongs to the Orthopoxvirus genus in the family Poxviridae. The Orthopoxvirus genus also includes variola virus (the cause of smallpox), vaccinia virus (used in the smallpox vaccine), and cowpox virus.
CDC, US: Monkeypox