Monkeypox is a very uncommon viral infection that produces a spotty, itchy and sore rash, and sometimes a fever. 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. It does not spread easily between people. The biggest risk of spread between people is through close physical contact, including sexual contact and close contact with household members.