This image may not be used in educational posters Monkeypox virus particles, illustration. At the centre of the monkeypox virus is a core nucleoprotein that contains the DNA (deoxyribonucleic acid) genome. This is surrounded by an outer envelope. 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. It is fatal in 10 per cent of cases.