Smallpox virus. Illustration of a smallpox (variola) virus. A membrane (transparent) derived from its host cell covers the virus particle. Inside this lies the core (green), which contains the particle's DNA (deoxyribonucleic acid) genetic material. The core has a biconcave shape. Smallpox is a disease that causes fever and often death. It was eradicated after a worldwide effort in the 1970s, but strains exist in research laboratories. The similar morphology is found in other viruses from the Poxviridae family, such as vaccinia virus, cowpox virus, monkeypox virus, molluscum contagiosum virus, tanapox virus, yaba monkey tumor virus, and other.