Animated of monkeypox virus particles. The virus has a core (red) that contains its double-stranded DNA genome. Around this is a protein coat and an outer envelope. It is a large virus, with dimensions of 250x200 nanometres. Infection causes the contagious disease monkeypox, which causes fever followed by a rash, like a milder version of the related smallpox. It is endemic to west and central Africa, but can cause outbreaks in other regions.