Illustration of a parvovirus B19 particle amongst blood cells. Parvoviruses consist of a single-stranded DNA (deoxyribonucleic acid) genome surrounded by an icosahedral protein capsid. Parvovirus B19 is the cause of erythema infectiosum, or Fifth disease. This childhood disease causes a red rash on the face, similar to a slap mark, which earns it the common name of slapped cheek disease. It usually causes a slight fever, but bed rest is the only treatment needed. It is more serious in adults, causing swelling and joint pain. In immunosuppressed people, it can cause anaemia and death.