Hand of a patient with monkeypox infection and close-up view of monkeypox virus particles, computer illustration. Monkeypox is a zoonotic virus from the Poxviridae family that causes monkeypox, a pox-like disease. This virus, which is found near rainforests in Central and West Africa causes disease in humans and monkeys, although its natural hosts are rodents. It is capable of human to human transmission. In humans it causes fever, swollen glands and a rash of fluid-filled blisters, shown in the illustration. It is fatal in 10 per cent of cases.